How to determine number of genetic loci that represent the mutant phrnotype in yeast?
Answers
Saccharomyces cerevisiae has been the model organism for most of the molecular genetics research in the past two decades for a number of reasons (1):
cerevisiae can stably exist in both haploid and diploid states. This allows scientists to easily isolate recessive mutants and map out genes that are responsible for a particular phenotype.
Foreign DNA in the form of plasmids or linear nucleotides can easily be transformed in cerevisiae. This has allowed scientists to conduct genetic complementation analysis and other engineering techniques (See point 3).
cerevisiae has a strong homologous recombination pathway and a high rate of gene conversion. Combined with the development of DNA transformation techniques, scientists can directly integrate exogenous DNA sequences into desired chromosomal loci, creating mutant strains with different markers.
There are hundreds of genetic markers available in cerevisiae (See below), which allow scientists to easily generate stable mutant strains (Point 3) or trace multiple markers simultaneously.
Since the genome sequence of cerevisiae is known, the science community has generated many genome-wide library collections of strains and plasmids. These collections are invaluable tools for scientists to perform genome-wide, large-scale genetics and genomics screens.
GENETIC MARKERS FOR SACCHAROMYCES CEREVISIAE
The nutritional requirements for yeast growth have been clearly defined over the years, and the pathways for synth these requirements have been discovered (2). If a biochemical step in one of these pathways is disrupted, yeast will no longer survive unless the missing nutrient is supplied in the growth media.
A wild-type yeast cell that has the ability to synth its own nutritional requirement is called a pro is called an aux. An aux marker is then defined as a wild-type allele of a gene that encodes a key enzyme for the production of an essential monomer used in biosynthesis,