Question

In order to identify genes that function together in genetic pathways researchers can perform modifier screens, looking for second site enhancers or suppressors of a mutant. Which of the following is the most reasonable strategy for carrying out a suppressor screen in particular?

a. analyze the DNA sequence near the mutation of interest, looking for sequences that may act as silencers.
b. identify mutations that, when crossed with the original mutant, result in synthetic lethality.
c. mutagenize the original mutant and look for new mutations that reduce the severity of the original mutant phenotype.
d. screen for enhancer-trap strains that show gene expression differences in the original mutant.
e. isolate mutants with phenotypes similar to the original mutant phenotype and then cross the mutants to identify the affected genes.

Answer 1

c. mutagenize the original mutant and look for new mutations that reduce the severity of the original mutant phenotype.

Step-by-step explanation:

A suppressor screen is a technique employed to identify a second mutation (i.e., a suppressor mutation) capable of reverting/alleviating the phenotypic effects associated with an initial mutation. There are two types of mutants obtained from this approach: 1-Intragenic suppressors, which involve second mutations inside the gene that restore the original function of the mutated gene; and 2- Intergenic suppressors, also known as extragenic suppressors, which involve second mutations in a gene that is distinct from the original mutated gene (usually extragenic suppressors function in the same signaling pathway as the original mutated gene).