Definition of Yeast artificial chromosome (YAC)

Yeast artificial chromosome (YAC): A vector (carrier) created and used in the laboratory to clone pieces of DNA.

A YAC is constructed from the telomeric, centromeric, and replication origin sequences needed for replication in yeast cells. (The telomere is the end of the chromosome; the centromere is the chromosome region to which spindle fibers attach during cell division; and the replication origin sequences are the spots where the replication of DNA starts.)