Baker's yeast, Saccharomyces cerevisiae, is a single-celled, diploid fungus (which is, of course, a eukaryote, that is capable of both meiosis and sexual reproduction).
Wild type yeast can normally grow on solid or liquid minimal medium; you isolate three mutant strains which are no longer capable of growing on minimal medium, however, they can grow on medium supplemented with adenine.
All three strains are homozygous for the underlying alleles.
When you cross mutant strain 1 and mutant strain 2, the offspring cannot grow on minimal medium and require adenine supplementation;
when you cross mutant strain 1 and mutant strain 3, the offspring can grow on minimal medium and do not require adenine.
A. What conclusions can you make about the alleles of mutant strains 1, 2, and 3 and their relationships with each other?
B. What phenomenon is occurring in the cross between mutant strains 1 and 3?
After crossing the F1 generation of the cross between mutant strains 1 and 3, you count and determine the phenotypes of 1,000 colonies (here a colony is equivalent to an individual): 563 colonies that can grow on minimal medium; 437 colonies that require adenine supplementation.
C. What genotypes lead to the phenotypes of the F2? What phenomenon is occurring in the F2 generation
Baker's yeast, Saccharomyces cerevisiae, is a single-celled, diploid fungus (which is, of course, a eukaryote, that is capable of both meiosis and sexual reproduction).
Wild type yeast can normally grow on solid or liquid minimal medium; you isolate three mutant strains which are no longer capable of growing on minimal medium, however, they can grow on medium supplemented with adenine.
All three strains are homozygous for the underlying alleles.
When you cross mutant strain 1 and mutant strain 2, the offspring cannot grow on minimal medium and require adenine supplementation;
when you cross mutant strain 1 and mutant strain 3, the offspring can grow on minimal medium and do not require adenine.
A. What conclusions can you make about the alleles of mutant strains 1, 2, and 3 and their relationships with each other?
B. What phenomenon is occurring in the cross between mutant strains 1 and 3?
After crossing the F1 generation of the cross between mutant strains 1 and 3, you count and determine the phenotypes of 1,000 colonies (here a colony is equivalent to an individual): 563 colonies that can grow on minimal medium; 437 colonies that require adenine supplementation.
C. What genotypes lead to the phenotypes of the F2? What phenomenon is occurring in the F2 generation
