Question 1

Which of the following best describes the difference between focused and dispersed promoters in eukaryotic gene regulation?

Accepted Answer

Focused promoters initiate transcription at a single start site, producing one major transcript, while dispersed promoters initiate transcription at several weak start sites, producing multiple transcripts.

Question 2

A mutation occurs in the TATA box of a gene's promoter region. Which of the following is the most likely consequence?

Accepted Answer

The gene will be transcribed at a lower rate or not at all due to impaired recognition by the transcription machinery.

Question 3

Which of the following DNA sequence elements is typically found at approximately -30 relative to the transcription start site and is crucial for the assembly of the pre-initiation complex?

Accepted Answer

TATA box

Question 4

The CAAT and GC boxes are examples of which type of regulatory element, and what is their primary function?

Accepted Answer

Proximal-promoter elements; they enhance the efficiency of basal transcription.

Question 5

Which of the following statements about enhancers is correct?

Accepted Answer

Enhancers can be located upstream, downstream, or even within the gene and are important for reaching maximum transcription levels.

Question 6

A researcher deletes the DNA-binding domain of a transcription factor. What is the most likely effect on gene expression?

Accepted Answer

The transcription factor will not bind to DNA, preventing it from regulating gene expression.

Question 7

Which protein motif is commonly found in transcription factors and is characterized by the coordination of a zinc ion with cysteine and histidine residues?

Accepted Answer

Zinc finger

Question 8

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

Accepted Answer

It binds to the UASG sequence and acts as an activator of GAL gene transcription in the presence of galactose.

Question 9

Which of the following best explains why humans can produce over 100,000 different proteins from only about 20,000 protein-coding genes?

Accepted Answer

Alternative splicing of pre-mRNA allows for the generation of multiple protein isoforms from a single gene.

Question 10

A mutation in a splicing enhancer sequence would most likely result in which of the following outcomes?

Accepted Answer

Reduced binding of SR proteins, leading to exon skipping or altered splicing patterns.

Question 11

Which of the following mechanisms is NOT a form of posttranscriptional gene regulation?

Accepted Answer

Enhancer-mediated activation of transcription

Question 12

The Dscam gene in Drosophila can produce over 38,000 unique polypeptides. Which molecular process is primarily responsible for this diversity?

Accepted Answer

Alternative splicing of multiple exons

Question 13

Which of the following statements about the p53 protein is correct?

Accepted Answer

p53 is a transcription factor that is rapidly degraded under normal conditions but stabilized in response to DNA damage.

Question 14

Which of the following best describes the function of ubiquitin in posttranslational regulation?

Accepted Answer

Ubiquitin tags proteins for degradation by the proteasome.

Question 15

A gene contains two alternative polyadenylation signals. What is the most likely result of using the downstream polyadenylation signal instead of the upstream one?

Accepted Answer

The resulting mRNA will have a longer 3' untranslated region (UTR).

Question 16

Which of the following is a direct effect of phosphorylation of the N-terminus of p53?

Accepted Answer

It prevents Mdm2 from binding, stabilizing p53 and allowing it to activate transcription of target genes.

Question 17

Which of the following types of alternative splicing involves the inclusion of an intron in the mature mRNA, potentially leading to its degradation or nuclear retention?

Accepted Answer

Intron retention

Question 18

Which of the following best describes the role of coactivators in transcriptional regulation?

Accepted Answer

They interact with activator proteins and help bridge them to the transcription complex, forming an enhanceosome.

Question 19

A mutation in the UASG sequence of the yeast GAL gene system would most likely result in which of the following?

Accepted Answer

Reduced or abolished binding of Gal4p, leading to decreased transcription of GAL genes even in the presence of galactose.

Eukaryotic Gene Regulation: Promoters, Transcription Factors, and Alternative Splicing

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