Question 1

Which of the following best describes the difference between cis-acting and trans-acting regulatory elements in gene expression?

Accepted Answer

Cis-acting elements are non-coding DNA sequences that regulate neighboring genes, while trans-acting elements are proteins or RNAs that regulate distant genes.

Question 2

A mutation in the enhancer region of a gene leads to decreased transcription of that gene. Which of the following best explains this observation?

Accepted Answer

The mutation disrupts the binding of an activator transcription factor, reducing the ability of the enhancer to stimulate transcription.

Question 3

Which of the following is a function of the TATA box in eukaryotic gene promoters?

Accepted Answer

It helps in the recognition and assembly of the basal transcription machinery at the core promoter.

Question 4

Which scenario best illustrates the role of an insulator in gene regulation?

Accepted Answer

An insulator sequence blocks the interaction between an enhancer and a promoter, preventing inappropriate activation of a neighboring gene.

Question 5

A researcher deletes the CAAT box from a gene's promoter. What is the most likely outcome?

Accepted Answer

Transcription will decrease because the CAAT box is important for binding transcriptional activators.

Question 6

Which of the following best describes the process of alternative mRNA splicing?

Accepted Answer

It allows for the production of different protein isoforms from a single gene by including or excluding certain exons.

Question 7

Which enzyme is responsible for cleaving double-stranded RNA into siRNA or miRNA during RNA interference?

Accepted Answer

Dicer

Question 8

A mutation in a silencer element leads to increased expression of a gene. What is the most likely explanation?

Accepted Answer

The mutation prevents the binding of a repressor protein, allowing transcription to proceed.

Question 9

Which of the following post-transcriptional modifications increases the stability of eukaryotic mRNA?

Accepted Answer

Addition of a 5' cap and a poly(A) tail

Question 10

In the context of RNA interference (RNAi), what is the role of the RNA-induced silencing complex (RISC)?

Accepted Answer

It binds to siRNA or miRNA and guides them to complementary mRNA targets for cleavage or translational repression.

Question 11

Which of the following is a direct effect of histone acetylation on gene expression?

Accepted Answer

It relaxes chromatin structure, increasing accessibility for transcription factors and RNA polymerase.

Question 12

A scientist observes that a gene is only expressed in the presence of both a specific activator and the absence of a repressor. Which regulatory logic does this illustrate?

Accepted Answer

Gene expression is controlled by combinatorial regulation involving both activators and repressors.

Question 13

Which of the following best explains how a hormone signal can lead to changes in gene expression in a target cell?

Accepted Answer

The hormone binds to a receptor, triggering a signal transduction cascade that activates transcription factors, which then enter the nucleus and regulate gene expression.

Question 14

Which of the following is a function of ubiquitin-mediated protein degradation?

Accepted Answer

It marks proteins for degradation by the proteasome through the addition of ubiquitin chains.

Question 15

Which RNA polymerase is responsible for synthesizing pre-mRNA in eukaryotic cells?

Accepted Answer

RNA polymerase II

Question 16

A single nucleotide polymorphism (SNP) occurs in the promoter region of a gene. Which of the following is a possible consequence?

Accepted Answer

The SNP could alter the binding affinity of transcription factors, leading to changes in gene expression.

Question 17

Which of the following best describes the role of microRNAs (miRNAs) in gene regulation?

Accepted Answer

miRNAs bind to complementary mRNA sequences and promote their degradation or inhibit their translation.

Question 18

Which of the following is true regarding the orientation and position of enhancers relative to the genes they regulate?

Accepted Answer

Enhancers can be located upstream or downstream, and can function in either orientation relative to the gene.

Question 19

Which of the following equations correctly represents the calculation of recombination frequency ($$RF) $$between two genes?

Accepted Answer

$$RF = \frac{	ext{Number of recombinant offspring}}{	ext{Total number of offspring}} 	imes 100$$

Transcriptional and Post-Transcriptional Regulation of Gene Expression

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