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Word / termDefinition

y axis

The vertical axis in a Cartesian Coordinate System.

Yasargil clip

A commonly used clip for cerebral aneurysms. The clip has relatively long tongs that permit insertion around the neck of an aneurysm.

Y chromosome

One of the two sex chromosomes, X and Y. One of two sex chromosomes in higher organisms that defines the gender of the adult. In almost all sexually reproducing organisms, the Y-chromosome defines male characteristics.

y-junction

The point of active DNA replication where the double helix opens up so that each strand can serve as a template.

Yeast

A unicellular fungus that lives in liquid or moist habitats, primarily reproducing asexually by simple cell division or by budding of a parent cell.

Yeast artificial chromosome (YAC)

A method for cloning very large fragments of DNA; a vector used to clone DNA fragments (up to 400 kb) originating from a bacterial plasmid. A YAC contains additionally a yeast centromeric region (CEN); a yeast origin of DNA replication origin sequence (ARS), the centromeric, and two telomere regions (TEL) needed for replication in yeast cells.. YACs are capable of cloning very large pieces of DNA. Genomic DNA in fragments of 200-500 kb are linked to sequences which allow them to propagate in yeast as a mini-chromosome (including telomeres, a centromere and an ARS - an autonomous replication sequence). This technique is used to clone large genes and intergenic regions, and for chromosome walking.

yeild

mass per unit time per unit area

y intercept

The value of y at the point where a curve crosses the y-axis.

Yolk

The stored food in egg cells that nourishes the embryo.

Yolk plug

A patch of vegetal cells (endoderm) that remains exposed in the blastopore after the formation of the ventral lip during gastrulation.

Yolk sac

One of four extraembryonic membranes that supports embryonic development; the first site of blood cells and circulatory system function.