Regulation Of Gene Expression In Eukaryotes - Genetic Analysis

Identifying an autosomal recessive mutation in a mutagenic screen in Drosophila requires identification of a mutant in the F₃ generation. If testing for a sex- linked recessive lethal mutation (e.g., cn l + using a balancer chromosome such as cnCyO), in which generation can lines with mutations be identified?

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Question 2

(Multiple Choice)

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A researcher is interested in testing the role for a highly- conserved amino acid in the function of a mouse protein. She has been unable to locate any pre- existing variants in this codon among a large number of available mouse strains. What might be her approach to generating such mutants?

A) Use RNAi to knockdown the expression of the target gene.
B) Use RNAi to interfere with translation of the gene.
C) Use transposons to generate insertion alleles in the gene.
D) Measure the expression of this gene in mice as they develop.
E) Use CRISPR- cas to cause DNA cleavage at the codon encoding this amino acid.

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Question 3

(Multiple Choice)

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

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