Question 1

Which of the following statements best distinguishes germ-line mutations from somatic mutations?

Accepted Answer

Germ-line mutations occur in sperm or egg cells and can be passed to the next generation.

Question 2

A point mutation that changes a codon but does NOT alter the amino acid sequence of the protein is called:

Accepted Answer

Silent (synonymous) mutation

Question 3

Which type of base-pair substitution mutation results in the replacement of a purine with another purine or a pyrimidine with another pyrimidine?

Accepted Answer

Transition

Question 4

A mutation in the promoter region of a gene most likely affects which aspect of gene expression?

Accepted Answer

The amount of protein produced

Question 5

Which repair mechanism is primarily responsible for correcting UV-induced thymine dimers in human cells?

Accepted Answer

Nucleotide excision repair

Question 6

A patient with xeroderma pigmentosum is most likely to have a defect in which DNA repair pathway?

Accepted Answer

Nucleotide excision repair

Question 7

Which of the following best describes a frameshift mutation?

Accepted Answer

An addition or deletion of one or more base pairs that alters the reading frame

Question 8

A trinucleotide repeat expansion is most likely to result in which type of genetic disorder?

Accepted Answer

Repeat expansion disorder, such as Huntington's disease

Question 9

Which equation best represents the mutation rate per gene per generation if 10 mutations are observed in a population of 100,000 gametes?

Accepted Answer

$$\frac{10}{100000}$$

Question 10

Which of the following mutagens is most likely to cause a transition mutation?

Accepted Answer

Deaminating agent

Question 11

A base excision repair pathway begins with the removal of a damaged base by which type of enzyme?

Accepted Answer

DNA glycosylase

Question 12

Which of the following is a consequence of a mutation in the polyadenylation signal sequence of the human beta-globin gene?

Accepted Answer

Improper 3' processing and reduced functional beta-globin protein

Question 13

Which repair pathway is activated in E. coli when DNA polymerase stalls at a lesion and allows replication to continue across damaged DNA?

Accepted Answer

Translesion DNA synthesis

Question 14

A mutation that creates a cryptic splice site in an exon is most likely to result in:

Accepted Answer

Improper mRNA splicing and abnormal protein product

Question 15

Which of the following is TRUE regarding homologous recombination during meiosis?

Accepted Answer

It requires double-strand breaks and strand invasion.

Question 16

Which protein is responsible for strand invasion during homologous recombination in eukaryotes?

Accepted Answer

RecA homologs such as Rad51 and Dmc1

Question 17

Which of the following best describes non-replicative (cut-and-paste) transposition?

Accepted Answer

The transposable element is excised from its original site and inserted into a new location.

Question 18

Which class of transposable elements in the human genome is most abundant and actively generates mutations?

Accepted Answer

LINEs (Long Interspersed Nuclear Elements)

Question 19

A true reversion mutation restores the wild-type phenotype by:

Accepted Answer

A mutation within the same codon that returns the original sequence

Question 20

Which equation best represents the probability of a mutation occurring at a hotspot with a mutation rate of $$10^{-4}$$ per gene per generation?

Accepted Answer

$$P = 1 - (1 - 10$$^{-4}$$)^n$$

Gene Mutation, DNA Repair, & Homologous Recombination – Chapter 11 Study Notes

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