Two different mutations are identified in a haploid strain of yeast. The first prevents the synthesis of adenine by a nonsense mutation of the ade-1 gene. In this mutation, a base-pair substitution changes a tryptophan codon (UGG) to a stop codon (UGA). The second affects one of several duplicate tRNA genes. This base-pair substitution mutation changes the anticodon sequence of a tRNATrp from 3'-ACC - 5' to 3'-ACU - 5'
1. Do you consider the second mutation to be a forward mutation or a reversion?
Do you consider the second mutation to be a forward mutation or a reversion?
second-site reversion (suppressor)
forward mutation
true reversion
intragenic reversion
2. Assuming there are no other mutations in the genome, will this double-mutant yeast strain be able to grow on minimal medium? ( yes or no)