Question 1

Which of the following best explains why gene regulation in eukaryotes is more complex than in bacteria?

Accepted Answer

Eukaryotes have multiple levels of regulation, including chromatin packaging and mRNA processing, which are absent in bacteria.

Question 2

A mutation in the CAAT box of a gene’s promoter most likely results in which of the following?

Accepted Answer

Decreased transcription levels due to impaired binding of sequence-specific DNA-binding proteins.

Question 3

Which chromatin modification is most directly associated with increased gene expression?

Accepted Answer

Histone acetylation, which neutralizes positive charges and loosens DNA-histone interaction.

Question 4

A scientist discovers a gene with multiple weak transcriptional start sites and constitutive expression in all cell types. Which promoter type does this gene most likely have?

Accepted Answer

Dispersed core promoter

Question 5

Which equation best represents the steady-state level of mRNA in a cell?

Accepted Answer

$mRNA_{steady-state} = Rate_{transcription} - Rate_{degradation}$

Question 6

Which of the following is a direct consequence of histone acetylation by HATs?

Accepted Answer

Decreased positive charge on histone tails, resulting in open chromatin and increased transcription.

Question 7

A patient with myotonic dystrophy exhibits symptoms due to a spliceopathy. Which molecular event is most likely responsible?

Accepted Answer

Defective alternative splicing resulting in abnormal mRNA isoforms.

Question 8

Which process is most likely to be affected if a cell’s proteasome is inhibited?

Accepted Answer

Degradation of poly-ubiquitinated proteins.

Question 9

Which of the following best describes the role of siRNAs in gene regulation?

Accepted Answer

They guide the RNA-Induced Silencing Complex (RISC) to complementary mRNAs for cleavage and degradation.

Question 10

A gene is silenced due to DNA methylation at its promoter. Which region is most likely methylated?

Accepted Answer

CpG island

Question 11

Which of the following is a function of long noncoding RNAs (lncRNAs) in gene regulation?

Accepted Answer

They alter gene expression and influence chromatin modifications.

Question 12

Which enzyme is responsible for adding acetyl groups to histone tails?

Accepted Answer

Histone acetyltransferase (HAT)

Question 13

Which of the following mechanisms allows a single gene to produce multiple protein isoforms with different functions?

Accepted Answer

Alternative splicing

Question 14

What is the primary function of the poly-A tail in eukaryotic mRNA?

Accepted Answer

To protect mRNA from degradation by exoribonucleases.

Question 15

Which of the following is true regarding the role of coactivators in transcription?

Accepted Answer

They serve as a bridge between activators and general transcription factors, facilitating pre-initiation complex assembly.

Question 16

A mutation causes premature stop codons in mRNA. Which cellular process is most likely activated?

Accepted Answer

Nonsense-mediated decay (NMD)

Question 17

Which of the following best describes the function of the RNA-Induced Silencing Complex (RISC)?

Accepted Answer

It binds to guide RNAs and targets complementary mRNAs for cleavage or translation inhibition.

Question 18

Which posttranslational modification is most likely to regulate protein activity by adding a phosphate group to serine, threonine, or tyrosine residues?

Accepted Answer

Phosphorylation

Question 19

Which of the following statements about chromatin remodeling is correct?

Accepted Answer

It involves repositioning or removal of nucleosomes to make DNA accessible for transcription.

Question 20

Which of the following is a direct effect of recruiting histone deacetylases (HDACs) to a gene’s promoter?

Accepted Answer

Decreased transcription due to closed chromatin.

Regulation of Gene Expression in Eukaryotes (Chapter 16) — Genetics Study Notes

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