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A yeast artificial chromosome (YAC) is an engineered self-replicating chromosome that can be inserted into yeast cells for reproduction as the cells grow and divide. In genetic research, people may need large quantities of genetic material, and a yeast artificial chromosome can be a useful cloning tool. This is important for sequencing and mapping genetic material, as well as amplifying DNA for testing. Labs can create their own YACs, or may order them from scientific suppliers who can insert the required material for a charge.
To produce yeast artificial chromosomes, technicians treat a segment of DNA to break it up and extract the component of interest, a fragment of genetic material. This can be inserted into a vector with all the necessary equipment to create a fully artificial chromosome. The genetic material can be replicated during the normal cell division process once yeast cells are inoculated with it. As the colony grows, so do the copies of the DNA fragment of interest, created by the yeast artificial chromosome.
Three components in addition to the DNA fragment are required to make a yeast artificial chromosome successful. The first is telomeres, which limit damage at the ends of the DNA to ensure it is copied correctly. Next is the centromere, which creates a point of attachment for the spindle fibers used in cell division to orient and divide chromosomes. Finally, replication origin sequences provide a starting point for DNA replication. These factors ensure that the yeast can successfully copy the alien chromosome.
The vectors allow scientists to insert DNA fragments of varying lengths into yeast colonies. Yeast that expresses the desired DNA can be isolated and cultured to encourage additional growth and the generation of enough genetic material for research. With this in hand, scientists can sequence the fragment, and this may help them determine what it does and where it is situated within the overall genome. While human DNA is a common target with yeast artificial chromosomes, it's also possible to use DNA from other organisms.
Labs that lack facilities to make their own can contract out these services. They may also do so if they want independent results that can be replicated by other researchers to verify the conclusions reached in the study. The use of duplicate yeast artificial chromosome specimens from multiple sources can demonstrate that the findings are valid. It can also reduce the risk of false results created by contamination, processing problems, and other issues that may arise in the lab.