Question 1

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

Accepted Answer

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

Question 2

Nonhomologous end joining (NHEJ) is most likely to occur during which phase of the cell cycle?

Accepted Answer

G1 phase

Question 3

A transposable element inserts into the promoter region of a gene. Which of the following is a possible outcome?

Accepted Answer

The gene may be silenced or aberrantly expressed, depending on the element's properties.

Question 4

Which of the following statements about autonomous and nonautonomous transposable elements is correct?

Accepted Answer

Autonomous elements encode the enzymes necessary for their own transposition.

Question 5

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

Accepted Answer

It provides the transposase enzyme required for Ds movement.

Question 6

Which of the following best explains why some corn 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 7

Which enzyme is responsible for converting the RNA intermediate of a retrotransposon into DNA?

Accepted Answer

Reverse transcriptase

Question 8

What is the primary difference between LTR and non-LTR retrotransposons?

Accepted Answer

LTR retrotransposons have long terminal repeats, while non-LTR retrotransposons do not.

Question 9

Which of the following is a consequence of transposon activity in bacteria?

Accepted Answer

Spread of multiple drug resistance genes between strains

Question 10

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 11

Histone acetylation generally has which effect on gene expression?

Accepted Answer

Activates transcription by decreasing histone-DNA affinity

Question 12

Which of the following is a cis-acting regulatory element that can increase the transcription of a gene from a distance?

Accepted Answer

Enhancer

Question 13

A mutation in the CAAT box of a promoter is most likely to affect which aspect of gene expression?

Accepted Answer

The efficiency of basal transcription levels

Question 14

Which of the following is true regarding alternative splicing?

Accepted Answer

It allows a single gene to produce multiple protein isoforms.

Question 15

Which protein tags other proteins for degradation by the proteasome?

Accepted Answer

Ubiquitin

Question 16

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

Accepted Answer

It binds to UASG and activates transcription of GAL genes in the presence of galactose.

Question 17

Which of the following best describes the effect of DNA methylation on gene expression in vertebrates?

Accepted Answer

It generally represses gene expression.

Question 18

A mutation that prevents the addition of a 7-methylguanosine cap to mRNA would most likely result in which outcome?

Accepted Answer

Decreased mRNA stability and translation efficiency

Question 19

Which of the following is a real-world consequence of P element transposition in Drosophila?

Accepted Answer

Hybrid dysgenesis, leading to sterility and high mutation rates in certain crosses

Question 20

Which of the following best explains why half of the human genome is composed of transposable elements?

Accepted Answer

Transposable elements can copy and insert themselves throughout the genome, contributing to genetic diversity.

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

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