Exam 14: Regulation of Gene Expression in Eukaryotes

Chemical mutagens are preferred to_______ because they have a broader mutation spectrum, including generating alleles that affect only a single codon.

A mutagenesis screen provides 24 alleles shown by complementation analysis to be in the same gene, which of the following is true?

What kind of analysis is needed to determine whether two mutations are in the same gene or in different genes?

A genetic strategy that starts with knowing the DNA sequence and works toward identifying an associated phenotype is known as ___________.

Which of the following tools/techniques would allow a researcher to measure the expression of a gene of interest in live organisms?

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?

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?

What method allows researchers to reduce the expression of a target gene, even in wildtype organisms that have not previously been genetically modified?

Transgenic fusions between a gene and a reporter are used to determine whether a gene is expressed. Which of these components allows the researcher to work with living specimens, and why?

Which technique can be used to replace an endogenous gene with one constructed in vitro?

Suppose a scientist works with a mouse strain B75 and isolates an interesting recessive mutant that they call glyph. The researcher wants to identify the gene affected in glyph by complementation cloning. Which strain would the researcher use as the source of DNA for transformation?

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?

You have performed an analysis of a gene promoter using a genetic reporter and a series of deletions. From this analysis, you identify a small deletion upstream of the start codon that causes increased expression of the reporter gene, compared to the expression of the reporter when it is fused to the wild type promoter. How do you explain the increased expression of the reporter in the mutant?

The GFP gene is useful as a reporter gene because the cells and tissues with it emit fluorescence when treated with what, which functions as a substrate?

You have performed a mutagenesis screening in a population of organisms. Describe how you would identify mutations that are dominant. Describe how you would identify mutations that are recessive.

In positional cloning, the researcher begins with a phenotype. To move toward identification of its DNA sequence, she must begin with what step?

Design an experiment that uses enhancer trapping to drive the expression of a gene of interest.

In Drosophila, mutation screening usually involves use of a balancer chromosome that includes three elements: a set of overlapping inversions, an easily recognized dominant mutation, and a recessive lethal mutation that prevents balancer homozygotes from surviving. Which one, or combination, of these elements is necessary and sufficient to suppress crossovers?

Which portion of a gene might you target with the CRISPR- cas system to interfere with splicing?

If you wish to use RNAi to reduce the expression of a gene in an organism. What would you inject into the organism?