Indicate the percentage of tetrads that would have 0,1, 2, 3, or 4 viable spores after Saccharomycescerevisiae a / α diploids of the following genotypesare sporulated:a. A true-breeding wild-type strain (with no mutations in any gene essential for viability).b. A strain heterozygous for a null (completely inactivating) mutation in a single essential gene.For the remaining parts of this problem, considercrosses between yeast strains of the form a × b, wherea and b are both temperature-sensitive mutations indifferent essential genes. The cross is conducted under permissive (low-temperature) conditions. Indicatethe percentage of tetrads that would have 0, 1, 2, 3, or4 viable spores subsequently measured under restrictive (high-temperature) conditions.c. a and b are unlinked, and both are 0 m.u. from thecentromere.d. a and b are unlinked; a is 0 m.u. from the centromere, while b is 10 m.u. from the centromere.e. a and b are 0 m.u. apart.f. a and b are 10 m.u. apart. Assume all crossoversbetween a and b are SCOs (single crossovers).g. In part (f), if a four-strand DCO (double crossover)occurred between a and b, how many of the sporesin the resulting tetrad would be viable at hightemperature?
Indicate the percentage of tetrads that would have 0,
1, 2, 3, or 4 viable spores after Saccharomyces
cerevisiae a / α diploids of the following genotypes
are sporulated:
a. A true-breeding wild-type strain (with no mutations in any gene essential for viability).
b. A strain heterozygous for a null (completely inactivating) mutation in a single essential gene.
For the remaining parts of this problem, consider
crosses between yeast strains of the form a × b, where
a and b are both temperature-sensitive mutations in
different essential genes. The cross is conducted under permissive (low-temperature) conditions. Indicate
the percentage of tetrads that would have 0, 1, 2, 3, or
4 viable spores subsequently measured under restrictive (high-temperature) conditions.
c. a and b are unlinked, and both are 0 m.u. from the
centromere.
d. a and b are unlinked; a is 0 m.u. from the centromere, while b is 10 m.u. from the centromere.
e. a and b are 0 m.u. apart.
f. a and b are 10 m.u. apart. Assume all crossovers
between a and b are SCOs (single crossovers).
g. In part (f), if a four-strand DCO (double crossover)
occurred between a and b, how many of the spores
in the resulting tetrad would be viable at high
temperature?
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