酵母菌人工染色体（Yeast artificial chromosome；YAC）是一种高容量选殖载体，可嵌入的外来基因大小范围可为100kb至3000k。此人工染色体系统含有酵母菌的端粒与着丝粒，和复制起点。可将特定的DNA置于端粒与着丝粒之间，使其在酵母菌体内复制。

进行选殖时可将目标串行以限制酶切下，再接合至酵母菌中，最早创建此系统的人是Murray & Szostak，于1983年创建。YAC具有EcoRI和BamHI这两种限制酶可辨识的位置。

除了YAC之外，YIP(yeast integrating plasmid)、YEps (yeast episomal plasmid)也是常用来和表现真核生物蛋白质的系统，在酵母菌中表现蛋白质时，可进行转译后修饰作用，然而YAC系统较细菌人工染色体系统不稳定。在人类基因体计划前，YAC和BAC系统是最常被用来作为特定基因保存或研究的工具。

Yeast artificial chromosomes (YACs) are genetically engineered chromosomes derived from the DNA of the yeast, Saccharomyces cerevisiae, which is then ligated into a bacterial plasmid. By inserting large fragments of DNA, from 100–1000 kb, the inserted sequences can be cloned and physically mapped using a process called chromosome walking. This is the process that was initially used for the Human Genome Project, however due to stability issues, YACs were abandoned for the use of Bacterial artificial chromosomes (BAC). Beginning with the initial research of the Rankin et al., Strul et al., and Hsaio et al., the inherently fragile chromosome was stabilized by discovering the necessary autonomously replicating sequence (ARS); a refined YAC utilizing this data was described in 1983 by Murray et al. The primary components of a YAC are the ARS, centromere, and telomeres from S. cerevisiae. Additionally, selectable marker genes, such as antibiotic resistance and a visible marker, are utilized to select transformed yeast cells. Without these sequences, the chromosome will not be stable during extracellular replication, and would not be distinguishable from colonies without the vector.