Molecular Biology of the Gene 7th Edition by Richard Losick, James Watson, Michael Levine, Tamara Baker, Alexander Gann

Exercise 3

You are screening E. coli for suppressor mutations for a mutant of your gene of interest. The mutation that currently causes the protein encoded by your gene to not be expressed is a nonsense mutation. One suppressor mutation is located in the gene encoding a less common tRNA Leu.
A. What type of suppressor mutation is described above?
B. Why is it more likely that a less common tRNA Leu carries a suppressor mutation than a very commonly used tRNA Leu ?
C. If you are told that the suppressor mutation only involves one point mutation and can translate the 5?-UAG-3? stop codon, give the sequence of the anticodon in the mutated tRNA Leu and the wild-type tRNA Leu.
D. Why is suppression of 5?-UAG-3? codons more efficient than suppression of the other stop codons?