Exam 12: Gene Mutation, Dna Repair, and Homologous Recombination

Given the DNA sequence 5′-TAC AAA ATA CAG CGG-3′, which of these sequences represents a missense mutation?

Which type of double-stranded break repair would you expect to be used by a cell in the G₁ phase of the cell cycle?

A bacterial culture has been exposed to UV radiation and is preparing to repair the DNA damage. Describe two mechanisms of repair used by E. coli to repair UV-induced DNA damage. Would you expect the bacteria to be able to repair more of the damage or less of the damage if they were placed in a dark environment after UV damage?

If you have screened 100,000 pollen grains and identified 5 mutants, what is the mutation frequency?

The compound 5-bromodeoxyuridine (BrdU)is a derivative of uracil, and if BrdU becomes incorporated during DNA replication, it pairs with adenine. This compound is best classified as which type of mutagen?

Which enzyme is the product of the phr gene in E. coli?

A strain of E. coli is unable to use the UV repair pathway because of an apparent absence of DNA helicase activity. Which UV repair gene is likely mutated in this strain?

Agents generating mutation-inducing DNA damage are collectively referred to as ________.

You are interested in studying the function of a gene, so you decide to create point mutations to help you identify important residues in your protein. Using the underlined adenine in the following sequence, how could you mutate the sequence to create a silent transversion mutation? 5′-ATG GGA TGG CAC CTG-3′

Explain what is meant by deamination. How does this mutation affect a cytosine (C)versus a methylcytosine (5meC)? What effect does deamination have on CpG islands, and how does that affect the mutation frequencies in these regions?

Studies of gene mutation frequencies have shown that __________.

Mutations can also occur within the regulatory regions of genes. Fragile X is an example of a disorder caused by one such mutation that increases the length of the long arm of the X chromosome and ultimately decreases mRNA stability. Which type of regulatory mutation causes Fragile X?

Which process is carried out by specialized bypass DNA that can replicate across the gaps induced during replication by UV damage?

Which mechanism can be used to repair UV damage in Drosophila but not in humans?

The Ames test is designed to identify the rate of ________ that restore the ability of bacteria to synthesize their own histidine, thus eliminating the need for histidine supplementation of the growth medium.

Which of these statements best describes gene expression in a damaged cell?

Which pathway is affected by an inherited mutation in the ATM gene?

Which of the following statements is true of non-homologous end joining (NHEJ)?

Which type of mutagen has a structure similar to one of the DNA nucleotides and therefore can work its way into DNA, where it pairs with a nucleotide?

What type of mutagen would you use if you wanted to study the effect of pyrimidine dimers in causing cancer?