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| Word / term | Definition |
|---|---|
Caffeine | A stimulant found naturally in the leaves, seeds or fruits of over 63 plant species worldwide especially coffee beans, tea leaves, cocoa beans (chocolate) and kola nuts (cola). Part of a group of compounds known as methylxanthines. Added to soft drinks, foods, and medicines. |
Calcitonin | Hormone secreted by the thyroid gland which controls the levels of calcium and phosphorous in the blood. |
Calcium channels | Calcium channels
Review |
Calmodulin | An intracellular protein to which calcium binds in its function as a second messenger in hormone action. |
Calorie | A unit of heat and a unit of food energy; Chemical energy in foods is expressed in calories (Cal). In heat terms, it is the amount of heat required to raise the temperature of 1 gram of water by 10°C from 14.5°C to 15.5°C. This is the true calorie, sometimes referred to as a "small calorie". One calorie (cal) equals 4.19 Joule (J). A kilocalorie is equal to 1000 calories and, likewise, the term kilo-calorie is the amount of heat required to raise the temperature of 1000 grams of water by 10°C. The kilo-calorie unit has largely been replaced by the Joule (1 kcal = 4.18 kJ). |
Caloric test | A test of vestibular function. Involves the induction of nystagmus by putting warm or cold water in the external auditory meatus. |
Calorimeter | An apparatus used to measure the amount of energy evolved or absorbed in a chemical or physical process. |
cAMP | The cyclic form of adenosine monophosphate.Used frequently as a second messenger in eukaryotics and in catabolite repression in prokaryotes. |
Canal hearing aid (also known as “In the ear hearing aid”) | A hearing aid that fits mostly in the ear canal with a small part of extending into the concha. It has a case molded to the user's ear. |
Canalized character | A character whose phenotype is kept within narrow boundaries even in the presence of disturbing environments or mutations. |
Cannabinoids | The psychoactive chemical substances found in marijuana (Cannabis sativa). |
Cancellous Screw | A screw designed for placement in cancellous bone. The pullout strength of a screw is proportional to the amount of metal-bone contact. Because cancellous bone is porous, threads for cancellous bone screws have to be longer than for cortical screws to achieve the same degree of metal-bone contact and thus have the same pullout strength as cortical screws. |
Cannula | Small tubing for insertion into a cavity or vessel. Generally used to remove fluid for sampling or to introduce fluids, gases or drugs. |
Cap (in molecular biology) | All eukaryotes have at the 5' end of their messages a methylated guanine residue called a "cap", consisting of a 7-methylguanosine in 5'-5' triphosphate linkage with the first nucleotide of the mRNA. It is added in reverse polarity (i.e. 3'pMeG5'ppp5'NpNp3') to the 5' end of eukaryotic mRNA during transcription initiation (i.e., post-transcriptionally) and is not encoded in the DNA. The cap binds a cap binding protein and acts as an initial binding site for ribosomes during translation. |
Capacitance | The separation of charge resulting in the storing of electrical energy across a space. In cells, membranes have capacitor properties contributing to the storage of electrochemical energy (ion gradients). |
Capacitation | Change in mammalian sperm that occurs after exposure to female genital tract making the sperm competent to undergo the acrosome reaction. This change is necessary for penetration of the cumulus matrix and for fertilization. Numerous molecular changes in the sperm are associated with capacitation, but the extent to which each event causes sperm capacitation is uncertain. |
Capacitor | a device that stores electric energy in the form of an electric charge. |
Capillary | The smallest of blood vessels, penetrates the tissues and consists of a single layer of endothelial cells that allows exchange between the blood and interstitial fluid. These are the main suppliers of nutrients (including oxygen) to tissue. |
Capillary action | The movement of water or any liquid along a surface ; The tendency of liquids to move into or out of tiny, hairlike passages. The means by which liquid moves through the porous spaces in a solid, such as soil, plant roots, and the capillary blood vessels in our bodies due to the forces of adhesion, cohesion, and surface tension. Capillary action is essential in carrying substances and nutrients from one place to another in plants and animals. the tendency of liquids to move into or out of tiny, hairlike passages. |
Capillary array | Gel-filled silica capillaries used to separate fragments for DNA sequencing. The small diameter of the capillaries permit the application of higher electric fields, providing high speed, high throughput separations that are significantly faster than traditional slab gels. |
Capsid | A protein coat that acts as a surface structure enclosing the genetic materials and enzymes of a virus; The protein "shell" of a free virus particle.Conical-shaped capsids made up of multimers of the capsid protein, CA, enclose the RNA genome of mature HIV-1 particles. The CA C-terminal domain (CTD) has a dimer arrangement that is retained in the assembled CA. An intermolecular CTD-CTD interface is critical for capsid stability. |
Cap site | In eukaryotes, the cap site is the position in the gene at which transcription starts, and really should be called the "transcription initiation site". The first nucleotide is transcribed from this site to start the nascent RNA chain. That nucleotide becomes the 5' end of the chain, and thus the nucleotide to which the cap structure is attached (see "Cap"). In bacteria, the CAP site (note the capital letters) is a site on the DNA to which a protein factor (the Catabolite Activated Protein) binds. |
Capsomere | Protein clusters making up discrete subunits of a viral protein shell. |
Capsule | A slimy layer around the cells of certain bacteria |
Carbohydrase | Enzyme that breaks down certain disaccharides into monosaccharides. |
Carbohydrate | A sugar (monosaccharide) or one of its dimers (disaccharides) or polymers (polysaccharides.Biochemical name for sugar containing molecules including single sugar (monosaccharides) like glucose and galactose, but also polysaccharides (complex carbohydrates) like starch (poly-glucose), cellulose (plant fiber material, also poly-glucose with a different chemical bond structure linking glucose units than those found in starch/glycogen and enzymatically indigestible by humans), chitin (hard shells of insects), and more complex carbohydrate components part of lipids and proteins such as blood serum glycoproteins (antibodies and blood group determinants A, O, B, rhesus positive or negative). All microorganisms (bacteria, viruses) contain carbohydrate surfaces (glycolipids) being the major determinants of immunogenic reactions during infections. |
Carbon | The element that defines the chemical properties of all life.All molecules that contain carbon are known as organic molecules and studies by organic chemistry. Carbon is the third most common element in cells, after hydrogen and oxygen, which are the most common biological elements because they are found in water. Also water makes up to 70% of a cells weight, it is not an organic molecule, since it lacks carbon. |
Carbondioxide | - a heavy colorless gas that does not support combustion, dissolves in water to form carbonic acid, is formed in animal respiration and in the decay or combustion of animal and vegetable matter, and is absorbed from the air by plants in photosynthesis. |
Carbonyl group | A functional group present in aldehydes and ketones, consisting of a carbon atom double-bonded to an oxygen atom. |
Carboxyl group | A functional group founding organic acids, consisting of a single carbon atom double-bonded to an oxygen and single-bonded to a hydroxyl group (OH). |
Carcinogen | An agent (chemical or radiation) that causes cancer. |
Carcinoma | Tumour arising from epithelial tissue (eg glands; breast; skin; linings of the urogenital, intestinal and respiratory systems). |
Cardiac cycle | The sequence of contraction and relaxation that makes up the heartbeat. |
Cardiac muscle | A type of muscle that forms the contractile wall of the heart; its cells are joined by intercalated discs that relay each heartbeat. |
Cardiac output | The volume of blood pumped by the heart in 1 minute |
Cardiac scan | Using a radioactive element to create an image of the heart showing uptake of radioactivity in various areas. Very low doses are used that are imaged by very sensitive, sophisticated detectors. Cardiac scans can identify areas of damaged or dead tissue, or reduced metabolism due to reduced or blocked blood flow. |
Cardiomyopathy | A diseased state of the heart involving abnormalities of the muscle fibers. |
Cardiovascular system | A closed circulatory system with a heart and branching network of arteries, capilleries, and veins. |
Carnivore | An animal, such as a shark, hawk, or spider, that eats other animals. |
Carotenoid | Yellow, orange and red pigments in plants, often masked by chlorophyll and thought to function as protective antioxidants. |
Carotid rete | A configuration of blood vessels in the brain that cools the brain. |
Carrying capacity | The maximum population size that can be supported by the available resources, symbolized as K. |
Cartesian coordinates | A system whereby points on a plane are identified by an ordered pair of numbers, representing the distances to two or three perpendicular axes. |
Cartilage | A supportive flexible connective tissue consisting of chondrocytes embedded in chondrin (collagen and proteoglycans). |
Cascade | A sequence of successive activation reactions involving enzymes (enzyme cascade) or hormones (hormone cascade) characterized by a series of amplifications of an initial stimulus. In blood coagulation, for example, each enzyme activates the next until the final product, the fibrin clot, is reached. |
Caspase | A type of enzyme known as proteases, which play essential roles in apoptosis (cell death) and inflammation. |
Cassette | A "package" of genetic material (containing more than one gene) that is inserted into the genome of a cell via gene splicing techniques. May include promoter(s), leader sequence, termination codon, etc. |
Catabolic pathway | A metabolic pathway that releases energy by breaking down complex molecules into simpler compounds. |
Catabolic reactions | Reactions in cells in which existing chemical bonds are broken and molecules are broken down.Generally these reactions produce energy, involve oxidation, and lead to a decrease in atomic order. Hence catabolism = Metabolic degradation reactions, which release energy. |
Catabolism | Within a cell or organism, the sum of all chemical reactions in which large molecules are broken down into smaller parts. The part of metabolism responsible for degradation of nutrients and energy extraction for the benefit of ATP production. |
Catabolite activator protein(CAP) | A protein that when bound with cyclic AMP (cAMP) can attach to sites on sugar-metabolizing operons to enhance transcription of these operons. In E. coli, a helper protein that stimulates gene expression by binding within the promoter region of an operon and enhancing the promoter's ability to associate with RNA polymerase. |
Catabolite repression | Repression (inactivation) of certain sugar-metabolizing operons (e.g. lac) in favour of glucose utilization when glucose is the predominant carbon source in the environment of the cell. |
Catalyst | Compound that speeds up or facilitates a reaction, by lowering the ctivation energy of a chemical reaction by forming a temporary association with the reacting molecules, without being altered in the process. Hence catalytic potential = The ability of a substance to increases the rate of a chemical reaction without itself being permanently changed. |
Catalytic or autocatalytic RNA (also known as Ribozyme) | RNA with enzymatic activity, for instance, self-splicing RNA molecules in Tetrahymena. |
Cataract | A clouding of the eye lens, which becomes opaque resulting in visual problems. |
Catarrhal deafness | Hearing loss resulting from inflammation of the mucous membrane of the air passages in the head and throat, with congestion of the Eustachian tube. |
CAT (chloramphenicol acetyl transferase) assay | An enzyme assay. Chloramphenicol acetyl transferase is a bacterial enzyme which inactivates chloramphenicol by acetylating it. CAT assays are often performed to test the function of a promoter. The gene coding for CAT is linked onto a promoter (transcription control region) from another gene, and the construct is "transfected" into cultured cells. The amount of CAT enzyme produced is taken to indicate the transcriptional activity of the promoter (relative to other promoters which must be tested in parallel). It is easier to perform a CAT assay than it is to do a Northern blot, so CAT assays were a common method for testing the effects of sequence changes on promoter function. Largely supplanted by the reporter gene luciferase. |
Catatonic behaviour | Marked motor anomalies, generally limited to disturbances in the context of a diagnosis of a non-organic psychotic disorder. |
Catatonic excitement | A psychotic disorder behavior characterized by excited motor activity, apparently purposeless and not influenced by external stimuli. |
Catatonic negativism | A psychotic disorder behavior characterized by an apparently motiveless resistance to all instructions or attempts to be moved. When passive, the person may resist any effort to be moved; when active, he or she may do the opposite of what is asked - for example, firmly clench jaws when asked to open mouth. |
Catatonic posturing | A psychotic disorder behavior characterized by the voluntary |
Catatonic schizophrenia | A marked psychomotor disturbance that may involve particular forms of stupor, rigidity, excitement or posturing. Sometimes when there is a rapid, alternation between the extremes of excitement and stupor, associated features include negativism, stereotypy and waxy flexibility. Mutism is common. |
Catatonic stupor | A psychotic disorder behavior characterized by a marked decrease |
Catatonic waxy flexibility | A type of psychotic disorder behavior in which a person's limbs can be "molded" into any position, which is then maintained. When the limb is being moved, it feels to the examiner as if it were made of pliable wax. |
Catechins. | Type of flavonoid found in tea. May provide the health benefits of neutralizing free radicals and possibly reducing the risk of cancer |
Category | In a hierarchical classification system, the level at which a particular group is ranked. |
Category scale | Items are placed in categories according to particular attributes, which can be verbally or numerically subdivided. |
Catheter | A hollow and flexible plastic tube that can be placed in a blood vessel for administration of solutions, collection of blood samples, or measurement of pressure. |
Cathode | A negatively charged electrode. |
Cation | A positively charged ion, which has more protons than electrons. |
Cation exchange | A process in which positively charged minerals are made available to a plant when hydrogen ions in the soil displace mineral ions from the clay particles. |
Cauda equina | Meaning “horses tail”; a bundle of spinal nerves at the base of the spinal cord. The descending ventral and dorsal roots of the lumbar sacral and coccygeal nerves that lie in the subarachnoid space at the caudal tip of the spinal cord. |
Caude equina syndrome | Impairment of the nerves in the cauda equina , the bundle of spinal nerve roots that arise from the lower end of the spinal cord . The syndrome is characterized by dull pain in the lower back and upper buttocks and lack of feeling ( analgesia ) in the buttocks, genitalia and thigh, together with disturbances of bowel and bladder function. |
Caudate nucleus | A brain structure within the basal ganglia of the brain. Responsible for regulating and organizing information being sent to the frontal lobes from other areas of the brain. The name caudate is given because it is a tail-shaped mass of neuron cell bodies. |
Causalgia | A burning pain due to injury of a peripheral nerve. |
Causality | A cause and effect relationship. The causality of two events describes to what extent one event is caused by the other. When there is causality, there is a measure of predictability between the two events. |
CCAAT box (CAT box, CAAT box, other variants) | An invariant DNA sequence at about minus 70 base pairs from the origin of transcription in many eukaryotic promoters. A sequence found in the 5' flanking region of certain genes which is necessary for efficient expression. A transcription factor (CCAAT-binding protein, CBP) binds to this site. |
CD4 protein | An adhesion molecule (protein) imbedded in the outer wall (envelope) of human immune system and brain cells that functions as the receptor (door to entry into the cell) for the HIV (AIDS) virus. The gp120 envelope glycoprotein of the HIV (i.e., AIDS virus) directly interacts with the CD4 protein on the surface of helper T cells to enable the virus to invade the helper T cells. |
CD44 protein | One of the adhesion molecules (embedded in the surface of the linings of blood vessels) that assists the neutrophils on their journey from the bloodstream through the walls of blood vessels (e.g., to combat pathogens into adjacent tissues).Tumor cells also exploit CD44 molecules in order to metastasize (spread throughout the body's tissue from a single beginning tumor) via a similar (tumor cell)-through-blood vessel- wall adhesion molecule mechanism. |
cDNA (complementary DNA) | A stretch of DNA which faithfully copies a particular stretch of messenger RNA (i.e., it complements the mRNA); DNA that is synthesized from a messenger RNA template. DNA copies synthesized from a messenger RNA template using the enzyme reverse transcriptase; the single-stranded copy is often used as a probe to identify complementary sequences in DNA fragments or genes of interest. The single-stranded form is often used as a probe in physical mapping. |
cDNA clone | cDNA is a piece of DNA copied from an mRNA.The term "clone" indicates that this cDNA has been spliced into a plasmid or other vector in order to propagate it.A cDNA clone may contain DNA copies of such typical mRNA regions as coding sequence, 5'-untranslated region, 3' untranslated region or poly(A) tail. No introns will be present, nor any promoter sequences (or other 5' or 3' flanking regions). A "full-length" cDNA clone is one which contains all of the mRNA sequence from nucleotide #1 through to the poly(A) tail. |
CD-ROM | Compact Disk Read Only Memory. A storage medium. Data are "stamped" onto the disk during the manufacturing process. The disk is read-only. |
Cell | Fundamental structural unit of all life; Smallest unit of life (single cell organism or bacteria) or unit of higher organisms, i.e., multicellular organisms. The cell consists primarily of an outer plasma membrane (and cell wall in bacteria and plants = a membrane plus some chemically more stable structures, often mixtures of proteins and polysaccharides), which separates it from the environment; the genetic material (DNA), which encodes heritable information for the maintainance of life; and the cytoplasm, a heterogeneous assemblage of ions, molecules, and fluid and contain all necessary elements to sustain life; proteins, nucleic acids, lipids, minerals, and a diverse class of metabolites.. Cells of higher organisms (known as eukaryotes) are subdivided into subcellular compartments called organelles such as the mitochondrion, the cell nucleus, the endoplasmatic reticulum, the Golgi apparatus and many smaller organelles with highly specialized functions. While all these organelles are found in animal cells, plant cells in addition contain a central vacuole that controls pressure to stabilize the cell and chloroplasts, the site of photosynthesis or light depended biosynthesis of sugars (carbohydrates). |
Cell autonomous | A genetic trait in multicellular organisms in which only genotypically mutant cells exhibit the mutant phenotype. Conversely, a nonautonomous trait is one in which genotypically mutant cells cause other cells (regardless of their genotype) to exhibit a mutant phenotype. |
Cell-based therapies | Treatment in which stem cells are induced to differentiate into the specific cell type required to repair damaged or destroyed cells or tissues. |
Cell centre | A region in the cytoplasm near the nucleus from which microtubules originate and radiate. |
Cell culture | Growth of cells in vitro in an artificial medium. |
Cell cycle | Complete sequence of steps which must be performed by a cell in order to replicate itself, as seen from mitotic event to mitotic event: The cycle of cell growth, replication of the genetic material and nuclear and cytoplasmic division. |
Cell cycle control system | A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle |
Cell fate | The ultimate differentiated state to which a cell has become committed. |
Cell fractionation | The disruption of a cell and separation of its organelles by centrifugation. |
Cell-free system | A mixture of cytoplasmic and/or nuclear components from cells and used for in vitro protein synthesis or transcription or DNA replication or other purposes. |
Cell fusion | The formation of a hybrid cell produced by fusing two different cells. |
Cell-mediated immunity | Immune reaction directed against body cells that have been infected by viruses and bacteria; controlled by T cells.Also called Cellular Immune Response. |
Cell membrane | The outer membrane of a cell, which separates it from the environment. Also called a plasma membrane or plasmalemma.Acts as a selectively permable barrier to allows the cell to create an internal environment (cytoplasm) with a separate identitiy to the extracellular environment. |
Cell plate | A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis. |
Cell theory | All living things are composed of cells; cells arise only from other cells. No exception has been found to these two principles since they were first proposed well over a century ago. |
Cell transport systems | Mechanisms used to move substances across the cell membrane, which acts as a selectively permeable barrier to allow the cell to maintain an internal environment different from the external one. |
Cellular automata | A simple mathematical system made of cells arranged on a grid; A program the applies a simple rule of what to do repeatedly. |
Cellular differentiation | The structural and functional divergence of cells as they become specialized during a multicellular organism's development; dependent on the control of gene expression. |
Cellular respiration | The transfer of energy from various molecules to produce ATP.Occurs in the mitochondria of eukaryotes and in the cytoplasm of prokaryotes. In the process, oxygen is consumed and carbon dioxide is generated. The most prevalent and efficient catabolic pathway for the production of ATP |
Cellulose | A structural polysaccharide of cell walls, consisting of glucose monomers joined by (1-4) glycosidic linkages. |
Cell wall | A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists. In the case of plant cells, the wall is formed of cellulose fibers embedded in a polysaccharide-protein matrix. Rigid structure deposited outside the cell membrane. The primary cell wall is thin and flexible, whereas the secondary cell wall is stronger and more rigid, and is the primary constituent of wood. Plants are known for their cell walls of cellulose, as are the green algae and certain protists, while fungi have cell walls of chitin. |
Celsius | a unit of measurement for temperature. Water freezes at 0ºC (zero degrees Celsius) and boils at 100°C (100 degrees Celsius). |
Celsius scale | A temperature scale (°C) equal to 5/9 (°F – 32) that measures the freezing point of water at 0°C and the boiling point of water at 100°C. |
Centimorgan (cm) | A chromosome mapping unit; A unit of measure of recombination frequency.One centimorgan equals 1% recombinant offspring, i.e., equal to a 1% chance that a marker at one genetic locus will be separated from a marker at a second locus due to crossing over in a single generation. In human beings, 1 centimorgan is equivalent, on average, to 1 million base pairs. |
Central angle | An angle that has its vertex at the center of a circle. |
Central auditory processing disorder (CAPD) | See Auditory processing disorder (CAPD) |
Central dogma | The original postulate that genetic information can be transferred only from nucleic acid to nucleic acid and from nucleic acid to protein, that is from DNA to DNA from DNA to RNA and from RNA to protein (although information transfer from RNA to DNA was not excluded and is now known to occur [reverse transcription]). |
Central limit theorem | This theorem states that the sum of a large number of random variables is approximately normally distributed, even though the random variables themselves may follow any distribution or be taken from different distributions. The only conditions are that the original random variables must have finite expectation and variance.Although the theorem is only true of an infinite number of variables, in practice the convergence to the Gaussian distribution is very fast. For example, the distribution of the sum of ten uniformly distributed random variables is already indistinguishable by eye from an exact Gaussian. |
Central nervous system | In vertebrate animals, the brain and spinal cord. |
Central pattern generators | Refer to networks of neurons in the spinal cord (and brainstem) that are capable of generating their own outputs to motorneurons independently of any descending or peripheral sensory input. CPGs are important in locomotion and respiration. |
Central venous pressure (CVP) | Pressure within the superior vena cava, which reflects the pressure under which the blood is returned to the right atrium |
Centre | The point that is the same distance from all the points on a circle. The point that is the same distance from all the points on a sphere. The point inside an ellipse where the major and the minor axes intersect. The center of a circle that can be inscribed in a regular polygon. |
Centre surround organization (in neuroscience: of the receptive field of a neuron) | A particular form of organization of the receptive field of a sensory neuron; generally a pattern of RF activity found in the visual system. The receptive field of the neuron describes the set of sensory receptors that elicit a response in the neuron. In the centre-surround pattern of organization of a RF, a stimulus at the centre of the neuron’s receptive field elicits one response (e.g. a depolarisation or 'on' centre response), while an annulus of light around it produces the opposite effect (e.g. a hyperpolarisation or 'off' surround response). |
Centrifugation | Separating molecules by size or density using centrifugal forces generated by a spinning rotor. Liquid samples are spun around at high speed to cause the accelerated settling of particles in suspension. G forces of several hundred thousand times gravity are generated in ultracentrifugation. |
Centriole | A structure in an animal cell, composed of cylinders of microtubule triplets arranged in a 9 + 0 pattern. An animal cell usually has a pair of centrioles, which are involved in cell division.A short cylindrical organelle, found in pairs arranged at right angles to each other at the centre of a microtubule organizing centre (MTOC) or centrosome, found in eukaryotes (except in higher plants). A centriole is similar in structure to the basal body found at the base of eukaryotic cilia and flagella and organises the axoneme, the bundle of microtubules and other proteins forming the core of each cilium or flagellum. The centrosome organizes formation of a spindle during mitosis or meiosis. |
Centroid | Synonymous with centre of gravity; Centre of mass of an object.The point where the object would balance if supported by a single support. The point in a triangle where the three medians intersect. Most often used for two- (or more-) dimensional distributions, designating the point given by the arithmetic mean in all variables. |
Centromere | The constricted centralized region of a nuclear chromosome, to which the spindle fibres attach during division. A kinetochore. |
Centrosome | The primary microtubule organising center (MTOC) of animal cells, that divides prior to cell division each daughter MTOC acts as one pole of the spindle apparatus. |
Cephalization | The concentration of sensory tissues in the anterior part of the body (head). |
Cerebellum | Part of the vertebrate hindbrain (rhombencephalon) located dorsally. Contains more neurons than the cerebrum and functions in unconscious coordination of fine movement and balance; likely to play an important role in other functions.but these are yet to be elucidated. Damage may result in ataxia. |
Cerebral cortex | The surface of the cerebrum; the largest and most complex part of the mammalian brain, containing sensory and motor nerve cell bodies of the cerebrum; the part of the vertebrate brain most changed through evolution. |
Cerebral lupus | A chronic autoimmune disease characterized by inflammation in the brain. |
Cerebral palsy | A condition caused by damage to the brain, usually occurring before, during or shortly following birth. Characterized by an inability to fully control motor function, general physical weakness, lack of coordination, and perceptual difficulties. Each characteristic can range from mild to severe. |
Cerebrovascular accident (CVA) | A "stroke". Arises because of the bursting of a blood vessel in the brain causing internal bleeding or a clot arising in a brain blood vessel (a thrombus) or elsewhere (embolus) and travelling to get stuck in a brain vessel which then deprives brain tissue of oxygen. |
Cerebrospinal fluid (CSF) | A clear, colorless, serum-like fluid that circulates through the ventricles and |
Cerebrum | The dorsal portion, composed of right and left hemispheres, of the vertebrate forebrain.Carried out a whole range of sensory and motor functions, as well as being the integrating center for memory, learning, emotions, and other highly complex functions of the central nervous system. |
cervical | Having to do with any kind of neck including the neck on which the head is perched and the neck of the uterus. The word "cervix" in Latin means "neck". That is why cervical vertebrae and cervical cancer involve quite disparate parts of the anatomy joined only by the meaning of the word "cervix". |
Cessation cassette | A three-gene cassette (genetic sequence construct) that, when inserted into a plant and when activated via tetracycline antibiotic, prevents the seeds produced by that plant from germinating.That is because the "cessation cassete" stops those resultant seeds from synthesizing a specific protein needed for seed germination. |
Chain reaction | Polymerisation initiated by the bonding of a free radical with a monomer. |
Channel (in data analysis or plots) | The measured value of a parameter, representing the signal intensity of an event after amplification. To appear on a plot, data for an event must fall into one of either 256 channels (0-255) or one of 1024 channels (0-1023) depending on the resolution of the plot. |
Channel Ioin channel) | A membrane protein that allows the passive flow of ions across a cell membrane. |
Character | Heritable trait possessed by an organism, that can be used for recognizing, differentiating or classifying a taxon.Biologists use characters from a variety of different sources, including morphological, behaviorial, developmental, and molecular data. Characters are usually described in terms of their states, for example: "hair present" vs. "hair absent," where "hair" is the character, and "present" and "absent" are its states |
Character displacement | A phenomenon in which species that live together in the same environment tend to diverge in those characteristics that overlap; exemplified by Darwin's finches. |
Character encoding scheme | A method of encoding characters including alphabetic characters (A-Z, uppercase and lowercase), numbers 0-9, punctuation and other marks (e.g. comma, period, space, &, *), and various "control characters" (e.g., tab, carriage return, linefeed) using binary numbers .For a computer to, for instance, print a capital A or a number 7 on the computer screen, we must have a way of telling the computer that a particular group of bits represents an A or a 7. There are standards, commonly called "character sets," that establish that a particular byte stands for an A and a different byte stands for a 7. The two most common standards for representing characters in bytes are ASCII ASCII and EBCDIC. |
Character format | Any file format in which information is encoded as characters using only a standard character encoding scheme . A file written in "character format" contains only those bytes that are prescribed in the encoding scheme as corresponding to the characters in the scheme (e.g., alphabetic and numeric characters, punctuation marks, and spaces. A file written in the ASCII character format, for instance, would store the number "7" in eight bits (i.e., one byte ): 00010111. A file written in EBCDIC EBCDIC would store the number "7" in eight bits as: 11110111. Contrast with binary format. |
Character state | Alternative forms of a character, a heritable trait (in genetics). |
Chargaff's rule | In the base composition of DNA the quantity of adenine equals the quantity of thymine and the quantity of guanine equals the quantity of cytosine. |
Charge | The state of an atom that has gained or lost an electron.The amount of unbalanced electricity in a system. Either positive or negative. |
Charon phage | Phage lambda derivative used as vector in DNA cloning. |
Chelator | Substance that binds particular ions, removing them from solution, e.g., EDTA is a chelator of divalent cations such as Mg++. |
Chemical bond | An attraction between two atoms resulting from a sharing of outer-shell elctrons or the presence of opposite charges on the atoms; the bonded atoms gain complete outer electron shells. |
Chemical equilibrium | The condition when the forward and reverse reaction rates are equal and the concentrations of the products remain constant. In a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction. |
Chemical indicator system | System using calibrated chemical agents (one type of which changes colour as a function of time and temperature of exposure to heat) to determine whether a process cycle has met the specified requirements. |
Chemical inertness or Chemically inert substances | Substances or elements which do not react easily with any other substances or elements. Chemically inactive materials. |
Chemical potential | The chemical potential of a substance, A, in
Its value is given by Analogous to electrical potentials (where electrons will flow from a region of high electrical potential to one of low potential) and gravitational potentials (where objects placed in regions of high gravitational potential will fall towards regions of lower potential). The same idea occurs in chemistry: molecules and/or ions will move from states of high chemical potential to states of low potential. (Note that when the chemical substance passes from the state of high chemical potential to a state of low potential energy, ‘free energy’, symbolized as DG, is made available to do work.)
where C is the concentration of A in phase a. From this comes the concept of concentration gradients with which students of biology are familiar in the context of movement of ions or other molecules across cell membranes. |
Chemical reaction | A process leading to chemical changes in matter; involves the making and/or breaking of chemical bonds. The transformation of substances by the rearrangement of their atoms. |
Chemiluminescence | The production of light photons by a chemical or electrochemical reaction. |
Cheminformatics | Computer software and hardware used in drug discovery and development programs for chemical screening and analysis. |
Chemiosmosis | The process by which ATP is produced in the inner membrane of a mitochondrion. |
Chemiosmotic coupling | The mechanism by which ADP is phosphorylated to ATP in mitochondria and chloroplasts. The energy released as electrons pass down an electron transport chain is used to establish a proton gradient across an inner membrane of the organelle; when protons subsequently flow down this electrochemical gradient, the potential energy released is captured in the terminal phosphate bonds of ATP. |
Chemoautotroph | An organism that derives energy from chemicals in nonliving surroundings. An organism that needs only carbon dioxide as a carbon source but that obtains energy by oxidizing inorganic substances. |
Chemoheterotroph | An organism that must consume organic molecules for both energy and carbon. |
Chemoreceptor | A receptor that transmits information about the total solute concentration in a solution or about individual kinds of molecules. |
Chemosynthesis | The biological synthesis of organic material using chemical reactions as an energy source. Microorganisms metabolically transform inorganic carbon to organic carbon (cells) using energy derived from oxidation of reduced compounds. Chemosynthesis is the basis for the food web associated with deep-sea hydrothermal vents. |
Chemosynthetic | Applied to autotrophic bacteria that use the energy released by specific inorganic reactions to power their life processes, including the synthesis of organic molecules. |
Chemotaxis | A process whereby a cell or organism follows chemical signals (chemo-) to move toward (-taxis) or away from a desired target.Commonly used to describe the developmental process of a neuron when its growth cone follows chemical signals to move toward a desired target. |
Chemotroph | An organism that obtains energy by oxidising chemicals. |
Chest | The area of the body located between the neck and the abdomen . The chest contains the lungs , the heart and part of the aorta . The walls of the chest are supported by the dorsal vertebrae , the ribs , and the sternum |
Chest x-ray | Commonly used to detect abnormalities in the lungs, but can also detect abnormalities in the heart, aorta, and the bones of the thoracic area. Metallic objects, such as jewelry are removed from the chest and neck areas for a chest x-ray to avoid interference with x-ray penetration and improve accuracy of the interpretation. |
Chest percussion | A technique in which the practitioner claps on the patient’s chest wall using a cupped hand to induce vibration throughout the lung parenchyma, facilitating bronchial secretion clearance. The technique may also be performed with the assistance of mechanical devices |
Cheyne-Stokes breathing | A breathing pattern which begins with short shallow breaths, increase in depth and frequency, reach a peak and then taper off. A short or long pause may follow. Defined as l0 to 30 seconds of apnea, followed by a gradual increase in the volume and frequency of breathing, followed by a gradual decrease in the volume of breathing until another period of apnea occurs |
Chiasma (plural = chiasmata) (in genetics) | A cross-shaped structure and/or a site where there is some physical cross over of structures. |
Chiasm (in vision) | The place in the brain at which nerves fibres from the nasal half of each eye cross over to join the nerve fibres ofrom the temporal half of the opposite eye and run with those fibres to the visual cortex. |
Chimera (or mosaic) | A tissue containing two or more genetically distinct cell types, or an individual composed of such tissues. Individual made up of two or more genetically distinct cell lines. |
Chimeraplasty | An experimental targeted repair process in which a desirable sequence of DNA is combined with RNA to form a chimeraplast. These molecules bind selectively to the target DNA. Once bound, the chimeraplast activates a naturally occurring gene-correcting mechanism. Does not use viral or other conventional gene-delivery vectors. |
Chimeric figure | A figure made up of two separate faces on each half (e.g., the left half of one person’s face matched with the right half of another person’s face.) |
Chimeric plasmid | Hybrid or genetically mixed plasmid used in DNA cloning. |
Chiral compound | A compound that contains an asymmetric center (chiral atom or chiral center) and thus can occur in two nonsuperimposable mirror-image forms (enantiomers). |
Chi site | Sequence of DNA at which the RecBCD protein cleaves one of the strands during recombination |
Chi-square distribution | Chi square, or goodness of fit, distributions are a family of probability distributions of the Chi-Square statistic, one for each degree of freedom. For small degrees of freedom, the distribution is skewed to the right. As the number of degrees of freedom increases, the distribution rapidly becomes symmetrical. For large degrees of freedom, the chi square distribution closely approximates a gaussian curve. |
Chi-square test | A statistical test used to determine the probability of obtaining the observed results by chance, under a specific hypothesis. A statistical test which computes the probability that there is no significant difference between the expected frequency of an occurrence with the observed frequency of that occurrence. |
Chloroplasts | A chlorophyll-containing plastid found in algal and green plant cells; An organelle found in eukaryotic algae and plants (and occasionally as symbionts in certain protist and animal cells). The site of photosynthesis and of chlorophyll. |
Chlorophyll | A family of pigments used in photosynthesis to trap radiant energy. Normally located with chloroplasts. Chloroplasts with chlorophyll b have a bright green colour, those with chlorophylls a and c are off-green or yellow. |
Cholesterol | A soft, waxy substance found among the fats in the bloodstream and in all the body's cells; Important lipid found only in animals. A steroid that forms an essential component of animal cell membranes, but also serves as a biosynthetic precursor molecule for the synthesis of other biologically important steroid hormones (e.g. sex hormones) and the active gall bladder ingredients bile acids (= detergents). The human liver can synthesize all the necessary levels of cholesterol and will reduce its own synthesis if cholesterol is taken in during a meal (only from animal sources). 'Bad' and 'Good' cholesterol refers to special transport particles of lipids in our blood serum called lipoprotein particles. The low density form or LDL is high in cholesterol and chronically high concentration of LDL in blood results in insoluble deposits that can clog arteries and restrict blood flow contributing to heart problems. |
Chondrin | A protein-carbohydrate complex secreted by chondrocytes; chondrin and collagen fibers form cartilage. |
Chondroitin Sulfate | Chondroitin sulfate is a chemical that is normally found in cartilage around joints in the body. |
Chord | A line segment that connects two points on a curve. |
Chordate | Organism having a notochord at some stage of development - a rigid cartilaginous rod in the back extending from anterior to posterior. A member of a diverse phylum of animals that possess a notochord; a dorsal, hollow nerve cord; pharyngeal gill slits; and a postanal tail as embryos. This group includes the vertebrates. |
Chorea | Basal ganglion disease characterized by rapid, complex, involuntary jerking movements of the skeletal muscles. Occurs especially for individual muscles or small muscle groups of the face, fingers and toes. |
Choreoathetosis | A form of cerebral palsy marked by variable muscle tone and involuntary movements of the arms and legs. |
Chorion | The outermost of the four extraembryonic membranes of amniotes; contributes to the formation of the mammalian placenta.It forms from the somatopleure (ectoderm and somatic mesoderm). In birds and reptiles, the membrane adheres to the shell and is highly vascularized to serve in gas exchange. In mammals, it forms the fetal contribution to the placenta, made by trophoblastic tissue and extraembryonic mesoderm, containing blood vessels that allow exchange of materials with maternal circulation |
Chorionic somatomammotropin | Hormone that promotes maternal breast development during pregnancy. |
Chorionic villus sampling (CVS) | A technique for prenatal testing for diagnosing genetic and congenital defects while the fetus is in the uterus. Fetal cells from the fetal side of the placenta (chorionic villi) are extracted and analyzed for chromosomal and biochemical defects |
Choroid | A vascular membrane in the eye containing pigment cells, which lies between the retina and sclera. |
Choroid plexus | A network of capillaries that projects into each brain ventricle, and the area where cerebrospinal fluid is produced. Ependymal cells (a type of neuroglial cell) surround these capillaries. Blood plasma entering the ependymal cells from the capillaries is filtered as it passes into the ventricle, forming CSF. The ependymal cells maintain a blood-CSF barrier controlling the composition of the CSF. |
Chromatid | A strand of a replicated chromosome, which are joined at the centromere; consists of DNA and protein. One of the two side by side replicas produced by chromosome replication in mitosis or meiosis. Subunit of a chromosome after replication and prior to anaphase of meiosis II or mitosis. At anaphase of meiosis II or mitosis when the centromeres divide and the sister chromatids separate each chromatid becomes a chromosome. |
Chromatin | A complex of DNA and protein in eukaryotic cells that is dispersed throughout the nucleus during interphase and condensed into chromosomes during meiosis and mitosis. The nucleoprotein material of the eukaryotic chromosome. |
Chromatin Immunoprecipitation (ChIP) | A method for isolating and characterizing the specific pieces of DNA out of an entire genome, to which is bound a protein of interest. |
Chromatin Remodeling | A re-shaping (at molecular scale) of chromatin (i.e., organism's complex of DNA and histone protein), that alters which specific genes in that organism's DNA subsequently get expressed.Can be caused by short interfering RNA (siRNA), certain transcription activators, acetylation of histone, methylation of histone, sumoylation of histone, etc. |
Chromatography | A method of separating a mixture of compounds by the use of a porous material, generally arranged in a column. |
Chromists | A term used variously to refer to some or all of those algae with chloroplasts having chlorophylls a and c (i.e. stramenopiles, cryptomonads, and haptophytes). |
Chromosomal mutation (also known as chromosomal rearrangement) | A mutation involving a long segment of DNA. These mutations can involve deletions, insertions, or inversions of sections of DNA. In some cases, deleted sections may attach to other chromosomes, disrupting both the chromosomes that loses the DNA and the one that gains it. |
Chromosome | The physical unit of genetic material in a cell; A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated specialized proteins called histones; A single DNA molecule that is the self-replicating genetic structure within the cell which carries the linear nucleotide sequence of genes; a linear end-to-end arrangement of genes and other DNA, sometimes with associated protein and RNA. |
Chromosome aberration | Any type of change in the chromosome structure or number (deficiencies, duplications, translocations, inversions, etc.).Although it can be a mechanism for enhancing genetic diversity, such alterations are usually fatal or ill-adaptive, especially in animals. |
Chromosome jumping | A technique of isolating clones from a genomic library that are not contiguous by skipping a region between known points on the chromosome. Done usually to bypass regions that are difficult or impossible to walk through or regions known not to be of interest. |
Chromosome map | A diagram of the linear order of the genes on a chromosome. |
Chromosome painting | The use of fluorescent-tagged chromosome-specific dispersed repeat DNA sequences to visualize specific chromosomes or chromosome segments by in situ DNA hybridization and fluorescence microscopy. |
Chromosome puff | A swelling at a site along the length of a polytene chromosome; the site of active transcription. A diffuse uncoiled region in a polytene chromosome where transcription is actively taking place. |
Chromosome region p | The short arm of a chromosome. |
Chromosome region q | The long arm of a chromosome. |
Chromosome set | The group of different chromosomes that carries the basic set of genetic information for a particular species. |
Chromosome walking | A technique for cloning everything in the genome around a known piece of DNA (the starting probe). It produces sets of overlapping DNA clones for studying segments of DNA larger than can be cloned individually. It allows analysis of large regions of DNA, in which a each end of a large single cloned DNA fragment is used separately to screen recombinant DNA genome library for other clones containing neighbouring sequences. |
Chronic | Marked by long duration or frequent recurrence. |
Chronic exposure | : A prolonged exposure occurring over days, weeks or years. |
Chronic bronchitis | Increased swelling and mucus (phlegm or sputum) production in the respiratory airways. Airway obstruction occurs in chronic bronchitis because the swelling and extra mucus causes the inside of the airways to be smaller than normal. Diagnosis of chronic bronchitis is made based on symptoms of a cough that produces mucus or phlegm on most days, for three months, for two or more years (after other causes for the cough have been excluded). (see Chronic Obstructive Pulmonary Disease) |
Chronic Obstructive Pulmonary Disease (COPD) | A preventable and treatable disease that is characterized by progressive airflow limitation that cannot be fully reversed, as well as abnormal inflammation due to chronic inhalation of particles or noxious gas. Symptoms of COPD rarely manifest in patients younger than age 40, though after onset, respiratory function declines precipitously over several years. COPD includes chronic bronchitis, emphysema, or a combination of both. (see Chronic bronchitis and Emphysema) |
Chyme | Digested content of the stomach released for further digestion in the small intestine. |
Chymotrypsinogen | A precursor of the digestive enzyme chymotrypsin (zymogen). This molecule is inactive and must be cleaved by trypsin, and then by other chymotrypsin molecules before it can reach its full activity. Its activity is the conversion of proteins to amino acids. The active site of the chymotrypsinogen is covered by a six amino acid long mask. It is only when this mask is removed - when it enters the lumen of the intestine and comes into contact with chymotrypsin molecules - that the enzyme becomes active. This is a very useful safety feature for a protein digesting enzyme. If it wasn't inactivated in this way it would digest the pancreas where it is produced. |
Cilium (plural = cilia) | A short cellular appendage specialized for locomotion, formed from a core of nine outer doublet microtubules and two inner single microtubules ensheathed in an extension of plasma membrane.Hair-like extensions of the cell, consisting of cytoplasm and the smaller organelles, extending from the membrane of many eukaryotic cells. Cilia often function in locomotion. A behavioural type of eukaryotic flagellum, distinctive because they occur in large numbers, have a co-ordinated behaviour, and usually direct fluids parallel to the surface. |
Ciliary body | part of the eye that joins the iris with the anterior portion of the choroid. |
Circadian rhythm | A physiological cycle of about 24 hours, present in all eukaryotic organisms, that persists even in the absence of external cues. |
Circle | The set of points in a plane that are a fixed distance from a given point. |
Circuit | The path followed by an electric current. Electricity must flow in a circuit to do useful work. |
Circular functions | Same as trigonometric functions. |
Circumcentre | The point in a triangle that is the center of the circle that can be circumscribed about the triangle. The intersection of the perpendicular bisectors of the triangle. |
Circumference | The distance around a closed curve. The circumference of a circle is 2*pi*r where r is the radius of the circle. |
Circumlocution | Use of other words to describe a specific word or idea which cannot be remembered |
Circumscribed circle | A circle that passes through all of the vertices of a regular polygon. |
Cirrhosis | Chronic liver disease characterized by gradual replacement of normal tissue by fibrous tissue leading to increasing loss of liver function. Due to several causes including alcohol abuse and viral hepatitis. |
Cis and trans isomers | Isomers related by rotation about a double bond. |
Cis conformation | In a heterozygote involving two mutant sites (a,b) within a gene or within a gene cluster, the arrangement ab/AB. |
Cis dominance | The ability of a gene to affect genes next to it on the same chromosome. Hence cis-dominant = mutations (eg of an operator) that alter the functioning of genes on that same piece of DNA. |
Cis-trans complementation test | 1. A mating test to determine whether two different recessive mutations (a1;a2) on opposite chromosomes (trans, a1+/+a2) of a diploid or partial diploid will not complement (ie have a mutant phenotype) each other; but the same two recessive mutations on the same chromosome (cis, a1a2/++) in a diploid or partial diploid show a wild-type phenotype. |
Cistron | The smallest genetic unit that does not show genetic complementation when two different mutations are in trans during a cis-trans complementation test; but shows wild-type phenotype when the same mutations are in cis. Synonymous with gene. |
Citric acid cycle (Krebs citric acid cycle) | A series of chemical reactions involved in aerobic respiration that occurs naturally in animals. |
Clade | A single complete branch of the Tree of Life; more formally, a monophyletic group of organisms. A monophyletic taxon; a group of organisms which includes the most recent common ancestor of all of its members and all of the descendants of that most recent common ancestor. |
Cladistics | A taxonomic approach that classifies organisms according to the order in time at which branches arise along a phylogenetic tree, without considering the degree of morphological divergence. |
Cladogenesis | The development of a new clade; the splitting of a single lineage into two distinct lineages; speciation. A pattern of evolutionary change that produces biological diversity by budding one or more new species from a parent species that continues to exist; also called branching evolution. |
Cladogram | A diagram, resulting from a cladistic analysis, which depicts a hypothetical branching sequence of lineages leading to the taxa under consideration. The points of branching within a cladogram are called nodes. All taxa occur at the endpoints of the cladogram. |
Clanging | Speech in which sounds, rather than meaningful, conceptual relationships govern word choice; it may include rhyming and punning. The term is usually applied only when it is a manifestation of a pathological condition; thus, it would not be used to describe the rhyming word play of children. Example: "I'm not trying to make noise. I'm trying to make sense. If you can make sense out of nonsense, well, have fun. I'm trying to make sense out of sense. I'm not making sense (cents) anymore. I have to make dollars." Clanging is observed most commonly in schizophrenic and manic episodes. |
Clasp knife reflex | Sudden release of tension of a spastic muscle that occurs near the maximum length as the muscle is gradually lengthened |
Class | A taxonomic grouping of related, similar orders; category above order and below phylum. |
Classical conditioning | A type of associative learning; the association of a normally irrelevant stimulus with a fixed behavioral response. |
Classification | The practice of arranging organisms in named groups (taxa). |
Cleavage furrow | A constriction of the cell membrane at the equator of the cell that marks the beginning of cytokinesis (cell division) in animal cells. The cell divides as the furrow deepens. |
Cleavage | The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. Specifically, the succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells |
Cleavage furrow | The first sign of cleavage in an animal cell; a shallow groove in the cell surface near the old metaphase plate. |
Cleaved amplified polymorphic sequence (CAPS) | A technique for identifing polymorphisms at a particular locus.The locus is amplified by PCR, followed by digesting with restriction enzymes. Polymorphisms may result in different size restriction fragments. |
Cleft lip / palate | A birth defect where there is a gap in the soft palate and roof of the mouth, sometimes extending through the upper lip. Results when the various parts of a lip or palate don't grow together to make a single lip or hard palate and is usually correctable. Affects eating, speech production, hearing and tooth formation. Clefting occurs during the sixth through thirteenth week of pregnancy.The degree of the cleft lip can vary greatly, from mild (notching of the lip) to severe (large opening from the lip up through the nose). Cleft lips may be caused by genetic or environmental factors. |
Cline | Variation in features of individuals in a population that parallels a gradient in the environment. |
Clipping | Used in image processing to describe when parts of an image are removed, usually delimited by straight lines.Images which are projections of three-dimensional computer objects may be clipped in 3-D, usually by one or several delimiting plane(s).Clipping is also in use for thresholding signal amplitudes or greyvalues in an image. |
Cloaca | A common opening for the digestive, urinary, and reproductive tracts in all vertebrates except most mammals. |
Clonal selection | The mechanism that determines specificity and accounts for antigen memory in the immune system.Occurs because an antigen introduced into the body selectively activates only a tiny fraction of inactive lymphocytes, which proliferate to form a clone of effector cells specific for the stimulating antigen. |
Clone | (1) A group of genetically identical cells or individuals derived by asexual division from a common ancestor: |
Cloning | The process of asexually producing a group of cells (clones), all genetically identical, from a single ancestor. In recombinant DNA technology, the use of DNA manipulation procedures to produce multiple copies of a single gene or segment of DNA is referred to as cloning DNA. |
Cloning vector | An agent used to transfer DNA in genetic engineering, such as a plasmid that moves recombinant DNA from a test tube back into a cell, or a virus that transfers recombinant DNA by infection.DNA molecule originating from a virus, a plasmid , or the cell of a higher organism into which another DNA fragment of appropriate size can be integrated without loss of the vectors capacity for self-replication. |
Clonus | A sustained series of rhythmic jerks following quick stretch of a muscle.The involuntary alternating contraction and relaxation of a rapidly extended muscle in spasticity. |
Closed circulatory system | A type of internal transport in which blood is confined to vessels. |
Closed interval | An interval that contains its endpoints. |
Closed loop (reflex) movements | Reflexly controlled movements that are guided by inputs from sensory systems. See Open-loop (or volitional) movements |
Cluster analysis | A multivariate statistical analysis method with several variables. Used to determine if data can be separated into discrete “clusters”, each of which is characterised by a particular combination of the same group of variables or criteria so that each cluster is differentiated from another from the same broad data set. |
Cluster ion | Ion formed by the combination of two or more identical ions or molecules in association with another atom, molecule, or ion. |
Cnidocyte | A stinging cell containing a nematocyst; characteristic of cnidarians. |
Coactivators | Molecules that help the transcription factors bind to the DNA in order for gene transcription to occur. |
Coagulation (of blood) | The clotting of blood. Coagulation is highly conserved throughout biology; in all mammals, coagulation involves both a cellular (platelet) and a protein (coagulation factor) component. The system in humans has been the most extensively researched and therefore the best understood. Coagulation is initiated almost instantly after an injury to the blood vessel damages the endothelium (lining of the vessel). Platelets immediately form a hemostatic plug at the site of injury; this is called primary hemostasis. Secondary hemostasis occurs simultaneously—proteins in the blood plasma, called coagulation factors, respond in a complex cascade to form fibrin strands which strengthen the platelet plug. Platelet activationDamage to blood vessel walls exposes collagen normally present under the endothelium. Circulating platelets bind to the collagen with the surface collagen-specific glycoprotein Ia/IIa receptor. This adhesion is strengthened further by the large multimeric circulating protein von Willebrand factor (vWF), which forms links between the platelet glycoprotein Ib/IX/V and collagen fibrils. The platelets are then activated and release the contents of their granules into the plasma, in turn activating other platelets. The platelets undergo a change in their shape which exposes a phospholipid surface for those coagulation factors that require it. Fibrinogen links adjacent platelets by forming links via the glycoprotein IIb/IIIa. In addition, thrombin activates platelets. The coagulation cascade. The coagulation factors are generally serine proteases (enzymes). There are some exceptions. For example, FVIII and FV are glycoproteins and Factor XIII is a transglutaminase. Serine proteases act by cleaving other proteins at specific sites. The coagulation factors circulate as inactive zymogens. The coagulation cascade is classically divided into three pathways. The tissue factor and contact activation pathways both activate the "final common pathway" of factor X, thrombin and fibrin. Thrombin then activates other components of the coagulation cascade, including FV and FVII (which activates FXI, which in turn activates FIX), and activates and releases FVIII from being bound to vWF. Contact activation pathway: There is formation of the primary complex on collagen by high-molecular-weight kininogen (HMWK), prekallikrein, and FXII (Hageman factor). Prekallikrein is converted to kallikrein and FXII becomes FXIIa. FXIIa converts FXI into FXIa. Factor XIa activates FIX, which with its co-factor FVIIIa form the tenase complex, which activates FX to FXa. The minor role that the contact activation pathway has in initiating clot formation can be illustrated by the fact that patients with severe deficiencies of FXII, HMWK, and prekallikrein do not have a bleeding disorder. Final common pathway: Thrombin has a large array of functions. Its primary role is the conversion of fibrinogen to fibrin, the building block of a hemostatic plug. In addition, it activates Factors VIII and V and their inhibitor protein C (in the presence of thrombomodulin), and it activates Factor XIII, which forms covalent bonds that crosslink the fibrin polymers that form from activated monomers. Following activation by the contact factor or tissue factor pathways the coagulation cascade is maintained in a prothrombotic state by the continued activation of FVIII and FIX to form the tenase complex, until it is down-regulated by the anticoagulant pathways. Cofactors: Various substances are required for the proper functioning of the coagulation cascade: Inhiibtors: Three mechanisms keep the coagulation cascade in check. Abnormalities can lead to an increased tendency toward thrombosis: Fibrinolysis: Eventually, all blood clots are reorganised and resorbed by a process termed fibrinolysis. The main enzyme responsible for this process (plasmin) is regulated by various activators and inhibitors. |
Coanda effect | It describes the tendency of moving air of fluids to follow the nearby curved or inclined surface. Described by Henri Coanda, a Romanian scientist, in the 1930's. |
Coccoid | Rounded in shape, ball-like. |
Cochlea | The complex, coiled organ of hearing that is responsible for starting the process of signalling via nerve fibres to the brain information about sound. The cochlea, also known as inner ear, contains the organ of Corti where hair cells convert mechanical motion, induced by sound waves striking the ear drum, into Action Potentials in nerve cells. These nerve cells then transmit that information to the brain where it is decoded and interpreted. |
Code (in data entry) | In most numeric data files, answers to questions are recorded with numbers rather than text and often even numeric answers are recorded with numbers other than the actual response. The numbers used in the data file are called "codes." Thus, for instance, when a respondent identifies herself as a member of a particular religion, a "code" of 1 might be used for Catholic, a 2 for Jewish, etc. Likewise, a person's age of 18 might be coded as a 2 indicating "18 or over." The codes that are used and their correspondence to the actual responses are listed in a codebook . The genetic code is the information needed to translate a nucleic acid (gene) sequence into an amino acid (protein) sequence. The code consists of triplet structures called codons such as UUG meaning two uracil and one guanine base along the messenger RNA template. This codon is recognized through base pairing by an anti-codon (triplet) on a transfer RNA. The transfer RNA is a specialized small ribonucleic acid that identifies genetic sequences on messenger RNAs (with the help of ribosomes) and carries one specific amino acid. An amino acid always matches one particular anti-codon. There are twenty amino acids to choose from for protein synthesis, and a total of 64 triplet codons (four bases in triplet sequence = 4x4x4 combinations). Thus there are 64 codons to match 20 amino acids, which means that some amino acids are coded by more than one codon. Which codons are responsible for which amino acid is evolutionarily conserved and most organisms have the same code or translation table. There are some alternate assignments found in mitochondrial genomes, viral genomes and some bacterial genomes. Yet, the fact that most organisms, bacteria, archaea and eukarya use the same genetic code explains the ability for recombinant DNA technology, i.e., to cut and past genetic elements from one organism into an other organism, since the assign amino acids to the same codons. Thus a human gene can be expressed in bacteria or yeast or jelly fish, and jelly fish genes can be expressed in bacteria, plants, fungi, animals and protists. There are almost limitless combinations possible. Read more about genetic codes at the National Center for Biotechnology Information and see the standard genetic code for humans and most organisms. |
Codebook | Generically, any information on the structure, contents, and layout of a data file. |
Code dictionary | A listing of the 64 possible codons and their translational meanings (the corresponding amino acids). |
Codominance | A phenotypic situation in which both alleles are expressed in the heterozygote. |
Coding efficiency | A measure of what fraction of the information contained in the neural spike train (i.e., a train of action potentials in a neuron) is actually used to code a stimulus |
Coding sequences | Sequences of nucleotides that signal RNA and proteins. |
Codon | A section of DNA (three nucleotide pairs in length) or RNA (three nucleotides in length) that codes for a single amino acid or termination signal. |
Codon repeat | A three letter sequence of bases (codon) that is repeated consecutively in a section of DNA. |
Coefficient | A constant that multiplies a variable. In Ax + By = C, A and B are coefficients of x and y. |
Coefficient of determination | The coefficient of determination, r 2,is useful because it gives the proportion of the variance (fluctuation) of one variable that is predictable from the other variable. |
Coefficient of Variation (CV) | A statistical measurement of the distribution of responses around the mean of those values; A statistical representation of the precision of a test. |
Coeliac disease (Also referred to as celiac sprue and gluten-induced enteropathy) | A chronic disease of the intestines that damages the body's ability to |
Coelem | A body cavity completely lined with mesoderm. A fluid-filled body cavity in animals, lined with tissue of mesodermal origin, housing the internal organs. |
Coelemate | An animal whose body cavity is completely lined by mesoderm, the layers of which connect dorsally and ventrally to form mesenteries. |
Coenocytic | Referring to a multinucleated condition resulting from the repeated division of nuclei without cytoplasmic division. Condition in which an organism consists of filamentous cells with large central vacuoles, and whose nuclei are not partitioned into separate compartments. The result is a long tube containing many nuclei, with all the cytoplasm at the periphery |
Coenzymes | Small non-protein organic molecules that help enzymes carry out biochemical reactions. Essential coenzymes are also known as vitamins. They bind to an enzyme and are required for its catalytic activity. Many of the vitamins are coenzymes or are converted into coenzymes in the body. |
Coevolution | The mutual influence on the evolution of two different species interacting with each other and reciprocally influencing each other's adaptations. |
Cofactor | Any nonprotein molecule or ion that is required for the proper functioning of an enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the substrate during catalysis. |
Cofunction | The cofunction of a trigonometric function, f(x), is equal to f(pi/2 - x). The cofunction of the sine is the cosine. The cofunction of the secant is the cosecant. The cofunction of the tangent is the cotangent. |
Cognition | The process or processes by which an organism gains knowledge or becomes aware of events or objects in its environment and uses that knowledge for comprehension and problem-solving; The conscious process of knowing or being aware of thoughts or perceptions, including understanding and reasoning. The high level functions carried out by the human brain, including comprehension and use of speech, visual perception and construction, calculation ability, attention (information processing), memory, and executive functions such as planning, problem-solving, and self-monitoring. |
Cognitive Rehabilitation | Therapy programs which aid persons in the management of specific problems in perception, memory, thinking and problem solving. Skills are practiced and strategies are taught to help improve function and/or compensate for remaining deficits. The interventions are based on an assessment and understanding of the person's brain-behavior deficits and services are provided by qualified practitioners. |
Cogwheel rigidity. | The form of rigidity of Parkinsonism in which the muscle lengthens in a series of little jerks when it is stretched. |
Coherent spectroscopy | The use of lasers to study the coherent interactions of excited atoms or molecules. |
Cohesion | The binding together of like molecules, often by hydrogen bonds |
Cohesion species concept | The idea that specific evolutionary adaptations and discrete complexes of genes define species. |
Cohesion-tension theory | A theory accounting for the upward movement of water in plants. According to this theory, transpiration of a water molecule results in a negative (below 1 atmosphere) pressure in the leaf cells, inducing the entrance from the vascular tissue of another water molecule, which, because of the cohesive property of water, pulls with it a chain of water molecules extending up from the cells of the root tip. |
Cohesive end | A single-stranded end to a linear duplex DNA molecule which can hydrogen-bond with a complementary single-strand base sequence from the end of the same or another DNA molecule. |
Coimmunoprecipitation | A purification procedure to determine if two different molecules (usually proteins) interact. An antibody specific to the protein of interest is added to a cell lysis. Then the antibody-protein complex is pelleted usually using protein-G sepharose which binds most antibodies. If there are any protein/molecules that bind to the first protein, they will also be pelleted. Identification of proteins in the pellet can be determined by western blot (if an antibody exist) or by sequencing a purified protein band. |
Cointegrate | A fusion of two elements. An intermediate structure in replicative transposition. The product of the fusion of two circular elements to form a single, larger circle. |
Coisogenic or congenic | Nearly identical strains of an organism that vary at only a single locus. |
Cold aclimation response | The process by which plants increase their tolerance to freezing by exposure to low, nonfreezing temperatures. |
Coliforms | Any fermentative (specifically lactose-fermenting) Gram-negative anaerobic enteric bacilli (E. coli-like). These bacteria (primarily E. coli and Enterobacter aerogenes) are used as an indicator of the sanitary quality of food. High levels of coliforms indicate the presence of fecal contamination in food and water. |
Colitis | Inflammation of the large intestine (the colon). There are many forms of colitis , including ulcerative colitis , Crohn's disease , infectious, pseudomembranous, and spastic. For example, intermittent rectal bleeding , crampy abdominal pain and diarrhea can be symptoms of ulcerative colitis. Diagnosis can be made by barium enema, but direct visualization (sigmoidoscopy or colonoscopy ) is the most accurate test. Long-standing ulcerative colitis increases the risk for colon cancer . Ulcerative colitis can also be associated with inflammation in joints, spine, skin, eyes, the liver and its bile ducts. Treatment of ulcerative colitis can involve medications and surgery. |
Collagen | A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone; the most abundant protein in the animal kingdom. |
Collecting duct | The location in the kidney where filtrate from renal tubules is collected; the filtrate is now called urine. |
Colligative properties | Properties which depend on the number of molecules in solution, a function of concentration and molecular weight, rather than just on the total percent concentration. Such properties include boiling point elevation, freezing point depression, and osmotic concentration. |
Collinear | Points which lie on the same line. |
Col plasmid | Plasmid that produces an antibiotic (colicin) used by the host to kill other strains of bacteria. |
Colinearity | A 1:1 linear correspondence between two related series of items. |
Colonial | Condition in which many unicellular organisms live together in a somewhat coordinated group. Unlike true multicellular organisms, the individual cells retain their separate identities, and usually, their own membranes and cell walls. |
Colony-forming unit | A unit of measurement for fungal or bacteria samples |
Colonscopy | Visualization of the lining of the anus, rectum and colon through a rigid proctosigmoidoscope or a flexible fiber optic endoscope. Allows diagnosis of tumors and inflammatory diseases. |
Colorectal cancer | A malignant disease of the colon and/or rectum which often begins as a polyp. |
Colorimetric label | A colorimetric label is an enzyme system in which an enzyme linked to a ligand or binder reacts with a specific substrate to generate a chromophore product. This tracer conjugate is quantified by measuring the amount of light absorbed by the product at a specific wavelength. Enzymes commonly used to label ligands or binders include alkaline phosphatase using para-nitrophenyl phosphate as substrate, horseradish peroxidase using hydrogen peroxide/coupler as substrate, and b-galactosidase using o-nitrophenylgalactoside as substrate. |
Column (in data entry) | In a data file, a single vertical column each being one byte in length. Fixed format data files are traditionally described as being arranged in lines and columns. In a fixed format file, column locations describe the locations of variables. |
Column location (in data entry) | The precise location in a data file of a variable expressed in column numbers, beginning with the first column in a physical record as column number 1 |
Coma | A state of unconsciousness from which the patient cannot be awakened or aroused, even by powerful stimulation; lack of any response to one's environment. Defined clinically as an inability to follow a one-step command consistently; Glasgow Coma Scale score of 8 or less. |
Combustible liquid | Liquids having a flash point at or above 100 degrees. Not as ignitable as Flammables. |
Commercial water use | Water used for motels, hotels, restaurants, office buildings, other commercial facilities, and institutions. Water for commercial uses comes both from public-supplied sources, such as a county water department, and self-supplied sources, such as local wells. |
Comma Separated Variable (CSV) | The simplest form of file for holding scientific, or other, data. Data is listed in columns in a text file, each value being separated by a comma. Each new line represents a new set of data. This format is used mainly on Windows-based PCs while Apple Macintosh computers tend to use the TSV format. (see also Tab Separated Variable) |
Commensal | An organism that derives nourishment or shelter by living in close association with another organism (the host), without damaging the host; Organisms existing in or on an animal or human without causing disease. Commensalism = A symbiotic relationship in which the symbiont benefits but the host is neither helped nor harmed |
Communicative Disorder | An impairment in the ability to 1) receive and/or process a symbol system, 2) represent concepts or symbol systems, and/or 3) transmit and use symbol systems. |
Commutative property | a + b = b + a. a*b = b*a. |
Compact bone | The outer dense layer that forms the shaft of the long bones; made up of concentric layers of mineral deposits surrounding a central opening. |
Comparison Probability | The comparison probability (Cpr Prob) is the probability that a standard curve is not significantly different from the reference assay standard curves. |
the following expression:
Comparative genomic hybridization (CGH) | CGH and FISH is a method for analyzing genomic DNA for unbalanced genetic alterations. Genomic DNA from the test sample (e.g., tumor cells) is labeled (e.g., orange/red) and mixed with normal genomic DNA labeled another color (e.g., green) and the mixture is hybridized (FISH) to a normal human metaphase spread or other reference standard. Regions of imbalance (increased or decreased copy number) in the tumor are located or mapped relative to the normal metaphase chromosomes as increases or decreases in the green to orange/red fluorescence ratio |
Compensation (in electronics) | An electronic calculation that removes signal overlap which the optical system cannot remove.e.g., Fluorescence compensation works for specific pairs of fluorescent parameters. |
Competition | Interaction between members of the same population or of two or more populations using the same resource, often present in limited supply. |
Competitive antagonist | See antagonist. |
Competitive assay | In this type of assay, a single concentration of radioligand is used in every assay tube (unlike the saturation experiment, in which the radioligand concentration is varied). The ligand is used at a low concentration, usually at or below its KD value. The level of specific binding of the radioligand is then determined in the presence of a range of concentrations of other competing non-radioactive compounds, in order to measure the potency with which they compete for the binding of the radioligand. Competition curves may also be computer-fitted to a logistic function as described under direct fit. |
Competitive binding assay | A competitive binding assay is an immunoassay reaction which is based upon the competition of labeled and unlabeled ligand for a limited number of binding sites on the binder. A fixed amount of labeled ligand (tracer) and a variable amount of unlabeled ligand are incubated with the binder. Following the law of mass action, the amount of labeled ligand which can bind to the binder is a function of the total concentration of labeled and unlabeled ligand. As the concentration of unlabeled ligand is increased, less labeled ligand can bind to the binder and the measured response is decreased. The standard curve of a competitive binding assay has a negative slope and is generally symmetrical at the midpoint |
Competitive exclusion principle | The concept that when the populations of two species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population. |
Competitive inhibitor | A substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics. |
Complementary angles | Two angles are complementary if their sum is 90 degrees. |
Complementary DNA | See cDNA |
Complementary nucleotides (Also known as Complementary base pairing) | The bonding preferences of nucleotides. |
Complement cascade | The precisely regulated, sequential interaction of proteins (in the blood) that is triggered by a complex of antibody and antigen to cause lysis of infected cells. |
Complement fixation | An immune response in which antigen-antibody complexes activate complement proteins. |
Complement system | A chemical defense system that kills microorganisms directly; a component of he body’s innate immune system. A group of at least 20 soluble proteins found in blood serum that interacts in a sequential fashion, in which a precursor molecule is converted into an active enzyme. Each enzyme uses the next molecule in the system as a substrate and converts it into its active (enzyme) form. This cascade of events and reactions leads ultimately to the formation of an attack complex that forms a transmembrane channel in the cell membrane (e.g., of a pathogen). It is the presence of the channel that leads to lysis (rupturing) of the cell. It supplements the inflammatory response, and works with, or complements, the immune system. |
Complete digestive tract | A digestive tube that runs between a mouth and an anus; also called alimentary canal. |
Completing the square | The method of adding an expression to both sides of an equation so that one side becomes a perfect square trinomial. |
Complex fraction | A fraction that contains a fraction in its numerator and/or denominator. |
Complexity | Complexity is the measure of the number and strength of interactions of its components. The components are organized not in a linear chain, but a network with specific connectivity, branches and loops. Network components affect each other through their interactions (molecular interactions). Complexity in biology is the result of dynamic interactions that follow each other in time and with both forward and feedback loops. Because of loops, the output of a network will affect a future input, thus continuously adjusting the physical output value of the system. Biological networks have evolved as stable systems. Stability means that biological systems are in homeostatic equilibrium, with information constantly flowing through the system and the output kept within a narrow range. |
Complex number | The sum of an imaginary number and a real number written in the form a + bi or r(cos x + isin x). |
Component | The components in the vector (a, b, c) are a, b, and c. |
Composite function | A function that consists of two functions arranged in such a way that the output of one function becomes the input of the other function. |
Composite hypothesis | A hypothesis with one or more free parameters. As an example, the hypothesis that the decay of a given particle is purely exponential with unknown lifetime, is a composite hypothesis. The testing of a composite hypothesis involves first estimating the unknown parameter(s). In the actual test, it is then necessary to compensate for the fact that the parameter(s) has (have) been fitted using the same data. Since one typically knows how to do this correctly only in the asymptotic limit of a large amount of data, such tests are never as safe as tests of simple (completely defined) hypotheses. |
Composite number | A natural number that is not prime. |
Compound | A chemical combination, in a fixed ratio, of two or more elements. From the Latin word componere = to put together. |
Compound eye | A type of multifaceted eye in insects and crustaceans consisting of up to several thousand light-detecting, focusing ommatidia; especially good at detecting movement |
Comprehension | Understanding of spoken, written, or gestural communication. |
Compulsion (as in disoreder) | An insistent, repetitive, intrusive and unwanted urge to perform an act |
Compulsive personality disorder | Restricted ability to express warm and tender emotions; preoccupation with rules, order, organization, efficiency and detail; excessive devotion to work and productivity to the exclusion of pleasure, indecisiveness. |
Concave | A figure is concave if a line segment can be drawn so that it goes in, out, then back into the figure. |
Concentration | 1. The concentration of a substance is a measurement of the mass of the substance per unit volume. |
Concentration gradient | A regular increase or decrease in the intensity or density of a chemical substance. |
Concentration scale | The analyte concentration scale is the scale used to graph the analyte concentration on the x-axis. The analyte concentration can be graphed on a logarithmic scale or on a linear scale. |
Concentration ratio | Concentration of agonist producing a defined response (usually but not necessarily 50% of maximum) in the presence of an antagonist, divided by the concentration producing the same response in the absence of antagonist. In figure B above the concentration ratio for curve B relative to control curve A is equal to the EC50 for curve B divided by the EC50 for curve A, i.e. 3x10(-8) / 1x10(-8) = 3. |
Concentration units | The concentration units are the units of measurements used to quantify the analyte |
Conclusion (in mathematics) | The part of an if - then statement that follows the word "then". Consequent. |
Concrete learning | A person's learning or cognitive style characterized as learning most efficiently by use of objects and tangible items. |
Concrete thinking | A style of thinking in which the individual sees each situation as unique and is unable to generalize from the similarities between situations. Language and perceptions are interpreted literally so that a proverb such as "a stitch in time saves nine" cannot be readily grasped. |
Concussion | The common result of a blow to the head or sudden deceleration usually causing an altered mental state, either temporary or prolonged. Physiologic and/or anatomic disruption of connections between some nerve cells in the brain may occur. Often used by the public to refer to a brief loss of consciousness. |
Condensation | When a substance changes state from a gas to a liquid. The process of water vapor in the air turning into liquid water. Water drops on the outside of a cold glass of water are condensed water. Condensation is the opposite process of evaporation. |
Condensation reaction | A reaction in which two molecules become covalently bonded to each other through the loss of a small molecule, usually water. Also called dehydration reaction. |
Conditional statement | An if - then statement. |
Conditioned play audiometry | Evaluation method for hearing sensitivity used by an audiologist where the child participates in a play activity (putting a ring on a cone, a block in a box, etc.) each time the signal is heard. |
Conditioned response | The response to a stimulus that occurs when an animal has learned to associate the stimulus with a certain positive or negative effect. |
Conductance | The flow of current (charged molecules and elements and measured in 'Siemens'); the inverse of resistance as defined by Ohm's law V = IR, where V is the voltage, R the resistance, and I the current. |
Conductor | - a thing that transmits heat, electricity, light, sound or other form of energy. |
Conduct disorder | A condition characterized by repetitive and persistent patterns of behavior that violate either the rights of others or age appropriate social norms or rules. |
Conduction | Heat or electricity transfer through molecular interaction, eg: heat passing along a metal bar. |
Conductive hearing loss | A type of hearing impairment that occurs when sound is not transmitted efficiently through the ear canal, ear drum, or the bones of the middle |
Conductivity (electrical) | Physical property of a material that determines its ability to conduct electricity. |
Conductivity (thermal) | Physical property of a material which determines its ability to conduct heat. Expressed in Watts/meter oC |
Cone | The union of all line segments that connect a point and a closed curve in a different plane from the point. |
Cones | photoreceptor cells in the retina used under conditions of bright illumination;are color coded (red, green, and blue); mediate fine detail vision; contain photopigments with low sensitivity to light (i.e., cannot see colors in dim illumination). |
Confabulation | Fabrication of facts or events in response to questions about situations or events that are not recalled because of memory impairment. Verbalizations about people, places, and events with no basis in reality. May be a detailed account delivered. Differs from lying in that the person is not consciously attempting to deceive. Confabulation is common in organic amnestic syndrome. |
Confidence limit | A statistical measure of the reliability of biological data values. Usually, 95% confidence limits are quoted. These would enclose the true value in 95% of repeated experiments. |
Confidence level | A measure usually associated with the comparison of observed value(s) with a probability density function (pdf). It expresses the probability that the observation is as far as observed or further away from the most probable value of the pdf, i.e., it corresponds to the integral over the pdf from the observed value to infinity. |
Confidence range | A numerical interval for a single parameter. This numerical interval is the range which encompasses a specified percentage of the corresponding parameter from the reference assay runs. |
Confusion | A state in which a person is bewildered, perplexed, or unable to self-orient. |
Congenital | Present at birth. A condition or disease existing at birth, that is not necessarily caused by inheritance. |
Congenital aphasia | The inability from birth to comprehend or produce language. This cannot be explained by sensory or motor defects or diffuse cerebral dysfunction. |
Congenital adrenal hyperplasia | Refers to a group of inherited adrenal gland disorders. People with this condition do not produce enough of the hormones cortisol and aldosterone, and produce too much of androgen.Newborn girls with this disorder have a swelling of the clitoris (ambiguous genitalia). Newborn males may have no obvious changes but may enter into puberty as early as age 2-3 years. Salt wasting is a lack of aldosterone causing a child to lose large amounts of salt in his/her urine. Non salt wasting is a lack of cortisol with enough aldosterone. |
Congenital blindness/adventitious deafness | An individual who has been visually impaired or blind since birth or early childhood and experiences hearing loss in adult life. Most common cause is trauma or infection. |
Congenital deafness/adventitious blindness | An individual who has been hearing impaired or deaf from birth or early childhood and experiences vision loss in adult life. |
Congenital heart disease (also termed Congenital Heart Defects) | Deformities, diseases, etc., in the heart and closely-allied blood vessels which are either present at birth, or which, being transmitted direct from the parents, show themselves some time after birth. Heart defects are the most common birth defect in the United States, occurring in about 1% of all live births, or a total of 40,000 newborns a year. CHDs include atrial and ventricular septal defects, patent ductus arteriosus, pulmonary stenosis and other valvular diseases, coarctation of the aorta, double outlet right ventricle, transposition of the great arteries, and hypoplastic left heart syndrome. |
Congenital Hypothyroidism | A disease in which the thyroid glands fail to develop normally. As a result, there is little or no thyroid hormone, which is necessary for normal growth and development of children. |
Congenital rubella | German measles contracted by a mother during pregnancy, which causes a variety of problems, including mental retardation, deafness, blindness, and other neurological problems. |
Congenital syphilis | Syphilis transmitted from a pregnant mother to her unborn child, which may cause spontaneous abortion, stillbirth, or other problems in the child. |
Congestive heart failure | Heart failure or improper functioning because of an unnatural accumulation of fluids around the organ. |
Congruent | Shapes or angles are congruent if you could put one on top of the other, and they would look like just one shape. Equal. |
Conic section | Parabola, hyperbola, ellipse, circle. Formed by the intersection of a plane with a right circular cone. |
Conjecture | A statement that seems to be true, but has not yet been proven. |
Conjoint analysis | Analytical methods which measure the contribution of single productc omponents to an overall result. Example, in olfactory perception, the contribution of single product components to the perception or preference formation on the basis of integral consumer judgments. |
Conjugate | The conjugate of a complex number is formed by reversing the sign on the imaginary part of the number. The conjugate of a + bi is a - bi. |
Conjugate eye movements | Both eyes move simultaneously in the same direction; Rotation of the eyes in the same direction at the same time. Convergence of the eyes toward the midline (crossed eyes) is a disconjugate movement. |
Conjugation | In bacteria, the transfer of DNA between two cells that are temporarily joined. A type of sexual event during which two cells fuse. It may or may not lead to reproduction. |
Conjunction | A statement that is really two statements joined by the word AND. Both parts must be true for the statement to be considered true. |
Conjunctiva | thin layer of mucous membrane lining the inner surface of each eyelid, |
Connective tissue | Animal tissue composed of cells embedded in a matrix (gel, elastic fibers, liquid, or inorganic minerals). Functions mainly to bind and support other tissues, having a sparse population of cells scattered through an extracellular matrix. Includes loose, dense, and fibrous connective tissues that provide strength (bone, cartilage), storage (bone, adipose), and flexibility (tendons, ligaments). |
Consensus profiling | Quantitative and qualitative description of all product-relevant attributes, with the final evaluation taking place in a group discussion. |
Consensus sequence | A ‘nominal’ sequence inferred from multiple, imperfect examples. Multiple lanes of shotgun sequence can be merged to show a consensus sequence. The optimal sequence of nucleotides recognized by some factor. A DNA binding site for a protein may vary substantially, but one can infer the consensus sequence for the binding site by comparing numerous examples. For example, the (fictitious) transcription factor ZQ1 usually binds to the sequences AAAGTT, AAGGTT or AAGATT. The consensus sequence for that factor is said to be AARRTT (where R is any purine, i.e. A or G). ZQ1 may also be able to weakly bind to ACAGTT (which differs by one base from the consensus). |
Consensual light reflex | Constriction of the pupil of the eye opposite that into which a light is shown |
Consequent (in mathematics) | The part of an "if - then" statement that follows the "then". Conclusion. |
Conservative replication (of DNA) | A proposed model of DNA replication. In this model the DNA helix is not unwound but somehow produces an entirely new strand of DNA. (see SemiConservative replication and Dispersive replication) |
Conserved sequence | A base sequence in a DNA molecule (or an amino acid sequence in a protein) that has remained essentially unchanged throughout evolution. |
Consistency check | A process of data cleaning which looks for inappropriate responses to branched questions. For instance, one question might ask if the respondent attended church last week; a response of "no" should skip the questions about church attendance and code the answers to those questions as "inapplicable." If those questions were coded any other way than "inapplicable this would be inconsistent with the skip patterns of the survey instrument. |
Conspecific | A member of the same species. |
Constant | A value that does not change. |
Constitutional delay of growth (late bloomer) | A normal variation of growth. A child will grow at a normal rate but appears smaller than children the same age. The bone age and the start of puberty are usually delayed. |
Constraints | In statistics means the same as degrees of freedom, i.e. the number of degrees of freedom is equal to the number of independent constraints. Note that constraint equations are not independent if they contain free parameters, as eliminating one unknown costs one equation. |
Construct validity | The degree to which inferences can legitimately be made from the operationalizations (the translation of a concept or construct into a functioning and operating reality) in a study to the theoretical constructs on which those operationalizations were based. Construct validity involves generalizing from your program or measures to the concept of your program or measures. Cn be considered a "labeling" issue, e.g., when you implement a program that you call a "Head Start" program, is your label an accurate one? When you measure what you term "self esteem" is that what you were really measuring? |
Consensus site | A sequence of similar (or very similar) nucleotide bases which is recognised by a transcription factor or RNA polymerase |
Consumptive use | That part of water withdrawn that is evaporated, transpired by plants, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Also referred to as water consumed. |
Containing group | A given group's containing group is that group in which this group is included as a subgroup. Any group in the Tree of Life has a series of hierarchically nested containing groups going all the way down to the ultimate containing group, Life on Earth. |
Content errors | Common errors made by children with language problems in which the semantics, or what the child understands or talks about, is limited or inaccurate. |
Contextual influences: | Influences arising as a result of the experimental conditions. Example, the way in which fatigue or alcohol or drug comsumption affects a person’s performance at a task; the way in which other stimuli in the background or what else the animal is doing influences the way in which a brain cell responds to a particular standard stimulus. |
Contig | A set of overlapping sequence fragments which constitute a chromosomal region. (The term comes from a shortening of the word ‘contiguous’.) |
Continuous (in mathematics) | A function is continuous if you can draw it without lifting your pencil off the paper. |
Continuous Positive Airway Pressure (CPAP) | The application of continuous pressure (both inspiration and expiration) for the spontaneously breathing patient. |
Continuous variation | A gradation of small differences in a particular trait, such as height, within a population; occurs in traits that are controlled by a number of genes. |
Contraception | The prevention of pregnancy. |
Contractile vacuole | In many protists, a specialized vacuole with associated channels designed to collect excess water in the cell. Part of the contractile vacuole complex, often the only part that is visible with the light-microscope. It collects fluid and, periodically, microtubules periodically contract to force this excess water out of the cell, regulating the cell's osmotic balance. |
Contractile vacuole complex | An organelle involved in osmoregulation in protist cells, including contractile vacuole, spongiome (a membranous system not usually visible with the light microscope), possibly a pore, collecting canals and ampullae. |
Contracture | Loss of range of motion in a joint due to abnormal shortening of soft tissues. |
Contrapositive | The contrapositive of A-->B is Not B---->Not A. |
Contrecoup | Bruising of brain tissue on the side opposite where the blow was struck. |
Control specimen | A control specimen is material from a single pool of unknown specimen(s) from which an aliquot is measured every assay run to monitor assay to assay reproducibility and to provide an indirect measurement of the performance of the assay components. |
Convection | The mass movement of warmed air or liquid to or from the surface of a body or object; Heat transfer through the movement of a fluid, eg: warm air rising. |
Convergent evolution | The independent development of similarity between species as a result of their having similar ecological roles and selection pressures. Adaptation for similar function may lead to novel characteristics (homoplasies), which are similar, although they are not inherited from a common ancestor. In some cases, such similarities may be superficial, as in the wings of birds, bats, and insects. In others, similarities can be so striking that it is difficult to determine that the traits arose independently and then later converged upon their current form. |
Convergent eye movements | Rotation of the eyes toward each other. Movement of two eyeballs inward to focus on an object moved closer. The nearer the object, the greater is the degree of convergence necessary to maintain single vision. |
Convergent series | An infinite series that has a finite sum is called convergent. |
Converse | The statement made by interchanging the hypothesis and the conclusion of a statement. |
Conversion symptom | A loss or alteration of physical functioning that suggests a physical disorder but is actually a direct expression of a psychological conflict or need. The disturbance is not under voluntary control, and is not explained by any physical disorder (this possibility having been excluded by appropriate investigation). Conversion symptoms are observed in conversion disorder, and may occur in schizophrenia. |
Convex | A set of points such that for any two points in the set, the line segment that connects them is also in the set. |
Conveyance loss | water that is lost in transit from a pipe, canal, or ditch by leakage or evaporation. Generally, the water is not available for further use; however, leakage from an irrigation ditch, for example, may percolate to a ground-water source and be available for further use. |
Convulsions | Rapidly alternating contractions and relaxations of the muscles, causing irregular movements of the limbs or body generally, and may be accompanied by unconsciousness. They form really only a symptom of some other trouble. The most common cause of convulsions in adults is epilepsy. Convulsions are rarely dangerous to life unless they occur as part of a dangerous condition which is already life threatening |
Cooperativity | An interaction of the constituent subunits of a protein causing a conformational change in one subunit to be transmitted to all the others. |
Coordinates | A set of numbers that identifies the location of a point. |
Coordinate systems | A system used to identify locations on a graph or grid; The mathematical description of a geometrical system (detector, magnetic field, etc.) can often be greatly simplified by expressing it in terms of an appropriate coordinate system. Examples of coordinate systems include Cartesian and Euclidean corordinates. |
Coplanar | Points that lie within the same plane. |
Corollary | A statement that can be easily proven once a theorem is proved. |
Cornea | convex, transparent coating of the eye (made up of collagen-rich epithelial cells) |
Cor pulmonale | Failure of the right ventricle resulting from disorders of the lungs or pulmonary vessels causing resistance to the passage of blood through the lungs and pulmonary hypertension. |
Corpus callosum | In the vertebrate brain, a tightly packed mass of myelinated nerve fibers connecting the two cerebral hemispheres. |
Corpus luteum | A secreting tissue in the ovary that forms from the collapsed follicle after ovulation and produces progesterone. Meaning “Yellow (luteum) body (corpus)”; the progesterone secreting body that is formed on the ovary after ovulation. |
Coronary artery disease | The obstruction of the coronary arteries that may be caused by fatty deposits (plaque) or thrombi. Obstruction of the coronary arteries can lead to decreased delivery of oxygen to the heart muscle, and the onset of symptoms. |
corrosive | A substance that causes visible destruction or permanent changes in human skin tissue at the site of contact, e.g. acids and bases. |
Correlation | A statistically-determined connection (relationship) between 2 factors / variables. The correlation coefficient is a a measure of the relation between the statistical distributions of the two random variables. |
Correlation coefficient | The quantity r, called the linear correlation coefficient, measures the strength and the direction of a linear relationship between two variables. The linear correlation coefficient is sometimes referred to as the Pearson product moment correlation coefficient in honor of its developer Karl Pearson. where n is the number of pairs of data. |
Cortex | The outer, as opposed to the inner, part of an organ. The outer part of the adrenal gland; of the brain |
Cortical Blindness | Loss of vision resulting from a lesion of the primary visual areas of the occipital lobe. Light reflex is preserved. |
Cortical screw | A screw designed for placement in cortical bone. See cancellous screw. |
Corticotrophin releasing hormone (CRH) or Corticotrophin releasing factor (CRF) | A hypothalamic neurotransmitter that controls the secretion of other stress-related hormones in the pituitary. CRF appears to be oversecreted in depression, perhaps contributing to some of the symptoms of depression such as decreased libido, insomnia, and decreased appetite, and CRF also may be involved in anxiety disorders. |
Cortisol | A steroid hormone produced by the adrenal gland. Involved in the stress response and increases blood pressure and blood sugar levels; promotes the formation of glucose from protein and fat; also suppresses the inflammatory and immune responses |
Cosine | In a triangle, the cosine of an angle = (length of the adjacent side)/(hypotenuse). |
Cosmid | Artificially constructed cloning vector containing the cos gene of phage lambda: a type of vector used for cloning 35-45 kb of DNA. |
Cost of test | The cost of a test is the probability of rejecting good events in hypothesis testing. |
Cosuppression | A significant decrease ("silencing") in the expression of a gene (within an organism's genome/DNA) that (often) results when man inserts and causes to be expressed a homologous gene. For example, high-oleic oil soybeans result when the GmFad2-1 gene (which codes for native 12 desaturase enzyme) is inserted and expressed in traditional varieties of soybeans. That is because the inserted gene "silences" itself and the endogenous GmFad2-1 gene (i.e., the one naturally/originally present in the soybean plant), which thus prevents formation of the 12 desaturase enzyme (which normally causes most oleic acid within soybeans to be converted into polyunsaturated linolenic acid/linoleic acid). |
Coterminal angles | Angles whose measures are 2kpi apart. |
Cotransport | The coupling of the "downhill" diffusion of one substance to the "uphill" transport of another against its own concentration gradient. |
Coulomb attraction | Electrostatic attraction between bodies of opposite charge. |
Countercurrent flow | A mechanism using the flow of two fluids in opposite directions to concentrate the amount of a chemical or gas in one fluid. This mechanism is used in the loops of Henle in the kidney to concentrate the urine. It is also the mechanism whereby fish obtain oxygen from the water that flows through their gills. Water flows across the respiratory surface of the gill in one direction while blood flows in the other direction through the blood vessels on the other side of the surface. |
Counting numbers | Natural numbers. The numbers you use to count. |
Counts per minute | Counts per minute (CPM) are the number of radioactive disintegrations which were recorded by a detector instrument during one minute. |
Coupled reactions | In cells, the linking of endergonic (energy-requiring) reactions to exergonic (energy-releasing) reactions that provide enough energy to drive the endergonic reactions forward. |
Covalent bonds | A chemical bond between atoms formed as a result of the sharing of one or more pairs of electrons. |
CpG island | Short region of DNA in which the frequency of the CG sequence is higher than in other regions. "p" indicates that "C" and "G" are connected by a phosphodiester bond. CpG islands are often located around the promoters of housekeeping genes (which are essential for general cell functions) or other genes frequently expressed in a cell. |
Cranial nerves | Nerves of the peripheral nervous system (and therefore nerves connecting to the body) that originate from or terminate in the brain. There are 12 pairs of cranial nerves, all of which pass through foramina of the skull. Cranial nerves are either sensory nerves (containing only or predominately sensory fibers) or mixed nerves (containing both sensory and motor fibers). |
Cranioschisis | The failure of proper fusion of the cephalic part of the neural tube. This leaves the brain and cranium open. The most extreme case results in anencephaly. |
Critical point | The point on a curve where the first derivative equals zero. Extremum. |
C-reactive protein | A protein that appears, usually within 24 hours, in the blood during the acute stage of inflammatory disorders such as rheumatic fever, or after a myocardial infarction (heart attack). The serum level of CRP is a sensitive indicator and monitor of rheumatic activity. |
CREB-binding protein (CBP) | An acetyltransferase enzyme which regulates genes by activating transcription. |
Cre-Lox System | Refers to the use of a particular phage/enzyme system to accomplish a site-specific (on organism's or virus's DNA) insertion or deletion of a specific DNA fragment. |
Crenulated | A surface with a regularly indented margin. |
Crepuscular | An adjective used to describe things relating to the twilight associated with sunrise and sundown. An organism is considered to be crepuscular if it is active primarily during the dawn and dusk hours. |
Crista (plural = cristae) | An infolding of the inner membrane of a mitochondrion. It houses the electron transport chain and the enzyme catalyzing the synthesis of ATP. |
Critical period | A time during the development of an animal when there is maximum plasticity in the evolving neural system, so that it can be most easily modified by environmental inputs. |
Crohn’s disease | An inflammatory bowel disease. The two most common forms of inflammatory bowel disease (IBD) are ulcerative colitis and Crohn`s disease. Crohn`s disease can occur anywhere within the digestive tract. While the most common complication of Crohn`s disease is blockage of the intestine, patients also frequently suffer from nutritional complications, and may develop skin problems, inflammation in the mouth or eyes, and diseases of the liver. |
Cross fertilization | Fusion of gametes formed by different individuals; as opposed to self-fertilization. |
Cross over design | A test in which two drugs (or one drug and placebo) are compared. The patient or animal is started on one treatment, and then after a specified time changed to the other treatment. |
Crossing over | The breaking during synapsis of meiosis I, of one maternal and one paternal chromosome, the reciprocal exchange of corresponding sections of DNA between nonsister chromatids, and the rejoining of the chromosomes. |
Cross reactivity | A measurement of the reactivity between a binder and a different ligand than the ligand to which the binder is specific. |
Cross sectional study | In survey research, a study in which data are obtained only once. |
Crown group | All the taxa descended from a major cladogenesis event, recognized by possessing the clade's synapomorphy. |
Cryogenic storage | The preservation of seeds, semen, embryos, or microorganisms at extremely low temperatures, below 130°C. At these temperatures, water is absent, molecular kinetic energy is low, diffusion is virtually nil, and storage potential is expected to be extremely long. |
Cryptogram | Nineteenth century concept broadly covering small algae, fungi, and bacteria. |
Crystal | Solid substance with a regular geometirc arrangement of atoms. |
CT Scan/Computerized Axial Tomography | A series of X-rays taken at different levels of the brain that allows the direct visualization of the skull and intracranial structures.A scan is often taken soon after the injury to help decide if surgery is needed. The scan may be repeated later to see how the brain is recovering. |
CTD | Pertaining to a system for measuring Conductivity (a measurement of salinity), Temperature and Depth (determined from pressure measurements). Additional parameters, such as pH and dissolved oxygen concentration, can be measured if optional sensors are installed. Often has Niskin bottles attached for taking water samples at specific depths |
Cube | A solid figure with six square faces. |
Cubic feet per second (cfs) | a rate of the flow, in streams and rivers, for example. It is equal to a volume of water one foot high and one foot wide flowing a distance of one foot in one second. One "cfs" is equal to 7.48 gallons of water flowing each second. As an example, if your car's gas tank is 2 feet by 1 foot by 1 foot (2 cubic feet), then gas flowing at a rate of 1 cubic foot/second would fill the tank in two seconds. |
Cubic polynomial function | A polynomial of degree 3. |
Cued speech | A communication method used by people with hearing disorders, which combines hand signals (cues) with speech-reading. Gestures provide additional information regarding sounds not identifiable by lip reading. |
Culture medium | A nutrient system for artificially growing bacteria or other cells: The liquid that covers cells in a culture dish and contains nutrients to nourish and support the cells. |
Cursor | A highlight appearing in a data field that indicates you can modify this field, on a dot plot, a crosshair for drawing a polygon gate, on histograms: a line separating regions on single parameter histograms that are treated statistically separate. |
Curve fit | Curve fit algorithms are mathematical formulas which compute a continuous curve function using discrete coordinate points. |
Current | the movement or flow of electric charges. |
Cushing's syndrome | A hormonal disorder caused by prolonged exposure of the body's tissues to high levels of the hormone cortisol. Sometimes called "hypercortisolism," it is relatively rare and most commonly affects adults aged 20 to 50. |
Cutaneous sensations | Sensations transmitted using specific sensors in the skin, the mucous membranes and deeper connective tissue layers (also tendons, muscular coats, periosteum) and which encompass the 3 sensory modalities, touch, heat and pain. |
Cyanobacteria | Photosynthetic, oxygen-producing bacteria (formerly know as blue-green algae). |
Cyanosis | A condition in which a lack of oxygen in the blood causes the blood to be darker and the skin to look bluish. |
Cyclamate | Sweetener which is 30 times sweeter than sucrose, calorie free and heat stable and works synergistically with other sweeteners. |
Cyclic AMP | Cyclic adenosine monophosphate, a ring-shaped molecule made from ATP. It is a common intracellular signaling molecule (second messenger) in eukaryotic cells, for example, in vertebrate endocrine cells. It is also a regulator of some bacterial operons. |
Cyclic electron flow | A route of electron flow during the light reactions of photosynthesis that involves only photosystem I and produces ATP but not NADPH or oxygen. |
Cyclin | A regulatory protein whose concentration fluctuates cyclically. |
Cyclin dependent kinase (Cdk) | A protein kinase that is active only when attached to a particular cyclin. |
Cyclotron | Accelerator in which particles move in spiral paths. |
Cyclotron resonance | Phenomenon that occurs when the frequency of revolving ions induced by a specific magnetic field intensity is similar to the frequency of that magnetic field and parallel to it. In these instances, energy may be transferred to the ions, affecting cell metabolic activities. |
Cylinder | The union of all line segments that connect corresponding points on congruent circles in parallel planes. |
Cystic fibrosis | A common fatal hereditary disease that usually appears early in childhood, in which there is production of a very thick mucus that interferes with normal digestion and breathing. Mutations in the CFTR gene (Transmembrane conductance regulator gene) cause a fundamental disorder of the exocrine glands, especially pancreatic enzyme deficiency and mucus accumulation in the airways. |
Cytochrome | An iron-containing protein, a component of electron transport chains in mitochondria and chloroplasts. |
Cytochrome c | Small heme protein in mitochondria. An essential component of the electron transfer chain that transforms energy in food into the energy-rich molecule ATP |
Cytokines | A large class of glycoproteins similar to lymphokines but produced by nonlymphocytic cells such as normal macrophages, fibroblasts, keratinocytes, helper T cells and a variety of transformed cell lines. They participate in regulating immunological and inflammatory processes, and can contribute to repair processes and to the regulation of normal cell growth and differentiation. |
Cytokinesis | The division of the cytoplasm to form two separate daughter cells immediately after mitosis |
Cytokinin | A class of related plant hormones that retard aging and act in concert with auxins to stimulate cell division, influence the pathway of differentiation, and control apical dominance. |
Cytomegalovirus (CMV) | Any of a group of DNA viruses causing the enlargement of the epithelial cells, especially the salivary glands, and associated with pneumonia and with abnormalities in newborn infants that affect various organs, resulting in mental retardation and other diseases. |
Cytopharynx | Part of the food ingestion structures (mouth) of some cells. Usually a channel of microtubules that draws newly formed food vacuoles away from the cytostome and into the cell. |
Cytoplasm | The entire contents of the cell, exclusive of the nucleus, within which organelles occur and which is bounded by the plasma membrane. |
Cytoplasmic determinants | In animal development, substances deposited by the mother in the eggs she produces that regulate the expression of genes affecting the early development of the embryo |
Cytoplasmic streaming | A circular flow of cytoplasm, involving myosin and actin filaments, that speeds the distribution of materials within cells |
Cytoproct | Found in some ciliates, the site at which old food vacuoles fuse with the cell surface, and undigested residues are excreted. |
Cytosine | A pyrimidne base (nitrogenous base) and constituent of nulceotides and as such one member of the base pair G-C (guanine and cytosine). |
Cytoskeleton | Literally “cell skeleton”; an integrated intracellular fibrous network of microfilaments, microtubules, neurofilaments, intermediate filaments and an assortment of proteins that branch throughout the cytoplasm within eukaryotic cells, used to provide shape to a cell or to create tracts along which cellular organelles may be moved. The cytoskeleton acts like scaffolding, anchoring internal cell structures and give the cell a definite structure and internal spatial organization, and maintains this structure, allowing the cell to modify its appearance during development, growth or injury. It also functions in cell movement and division motility, and may assist in communication with other cells and the environment. Red blood cells, for instance, would be spherical instead of flat if it were not for their cytoskeleton. |
Cytosol | The semifluid portion of the cytoplasm. |
Cytostome | Literally, 'the cell mouth'. only used in reference to organisms which ingest food at one or more particular locations, and then best used in reference to the region(s) of the cell surface through which food gains entry into the cell; part of the 'mouth' structures. |
Cytotoxic or killer T cells | A type of lymphocyte that kills infected cells and cancer cells. T cells that destroy body cells infected by viruses or bacteria; also attack bacteria, fungi, parasites, and cancer cells and will kill cells of transplanted organs if they are recognized as foreign. |
