Question 1

Which of the following best describes the initial step in homologous recombination repair of a double-strand DNA break?

Accepted Answer

The 5' ends are digested to create 3' overhangs.

Question 2

A patient’s cells are unable to repair double-strand breaks during the G1 phase. Which repair pathway is most likely defective?

Accepted Answer

Nonhomologous end joining

Question 3

Which of the following is a potential consequence of a transposable element inserting into the promoter region of a gene?

Accepted Answer

The gene may be silenced or misexpressed, depending on the transposon’s properties.

Question 4

In the Ac-Ds system in maize, what is the role of the Ac element?

Accepted Answer

It provides transposase, enabling both its own and Ds movement.

Question 5

Which of the following best explains why some maize kernels are speckled in color?

Accepted Answer

The Ds element is excised from the C gene during development, restoring pigment production in some cells.

Question 6

Which of the following is TRUE regarding retrotransposons?

Accepted Answer

They use an RNA intermediate and require reverse transcriptase for movement.

Question 7

A bacterial strain acquires resistance to multiple antibiotics after conjugation with another strain. Which genetic element is most likely responsible?

Accepted Answer

A large transposon carrying drug resistance genes

Question 8

Which of the following statements about chromatin structure and gene expression is correct?

Accepted Answer

Methylation of cytosine residues in DNA is associated with gene silencing.

Question 9

Which of the following best describes the function of the SWI/SNF chromatin remodeling complex?

Accepted Answer

It repositions or removes nucleosomes to make DNA accessible for transcription.

Question 10

A mutation in the TATA box of a gene’s promoter is most likely to affect which process?

Accepted Answer

The efficiency and accuracy of transcription initiation

Question 11

Which of the following is a key difference between focused and dispersed promoters?

Accepted Answer

Focused promoters direct transcription from a single start site, while dispersed promoters initiate transcription from several weak start sites.

Question 12

Which of the following best describes the role of enhancers in eukaryotic gene regulation?

Accepted Answer

They can be located far from the gene and increase the rate of transcription initiation.

Question 13

Which protein motif is commonly found in the DNA-binding domain of transcription factors?

Accepted Answer

Zinc finger

Question 14

In the yeast GAL gene system, what is the function of the Gal4 protein?

Accepted Answer

It is an activator that binds to UASG and promotes transcription of GAL genes.

Question 15

Alternative splicing of pre-mRNA allows for which of the following outcomes?

Accepted Answer

Production of multiple protein isoforms from a single gene

Question 16

Which of the following mechanisms is used by cells to regulate the steady-state level of mRNA?

Accepted Answer

A combination of transcription rate and mRNA degradation rate

Question 17

A mutation in the gene encoding the ubiquitin ligase Mdm2 would most likely affect which cellular process?

Accepted Answer

Degradation of the p53 protein

Question 18

Which of the following is a direct result of phosphorylation of the N-terminal tail of p53?

Accepted Answer

p53 is protected from degradation and can activate transcription of its targets.

Question 19

Which of the following best explains the phenomenon of genetic imprinting?

Accepted Answer

Only one allele of a gene is expressed, depending on the parent of origin.

Genetic Mechanisms: Double-Strand Break Repair, Transposable Elements, and Regulation of Gene Expression

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