How can we know cloned gene is responsible for mutant phenotype in yeast?
Answers
In E. coli and yeast a specific gene defined by mutations can be isolated by transforming cells exhibiting the mutant phenotype with various plasmids that collectively represent the total genomic DNA. Those plasmids that carry the gene of interest will restore the mutants to the wild-type phenotype, which can be identified easily. These plasmids can rescue mutants because they carry a normal copy of genes. This DNA-rescue approach is feasible in E. coli and yeast because collections of plasmids representing the entire genome are available and can be effectively transferred into mutants. Although individual cloned genes can be introduced into genetically tractable higher organisms (e.g., Drosophila, C. elegans, and mice), these methods are not efficient enough to be used for screening DNA libraries representing the entire genome.
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