Q: Which equation best represents the exponential decay of protein concentration due to proteasome-mediated degradation, assuming a half-life $$t_{1/2}$$?

$$C(t) = C_0$ \times e$$^{-kt}$$, where k$$ = \frac{\ln 2}{t_{1/2}}$$

Question 1

Which of the following best describes the role of the TATA box in eukaryotic gene expression?

Accepted Answer

It is a promoter element that helps position RNA polymerase II for transcription initiation.

Question 2

A researcher observes that a gene is not being transcribed in a particular cell type, despite the presence of RNA polymerase II. Which regulatory mechanism is most likely responsible?

Accepted Answer

Absence of general transcription factors at the promoter.

Question 3

Which of the following statements about histone acetylation is correct?

Accepted Answer

Histone acetylation attaches acetyl groups to lysine residues, loosening chromatin and promoting transcription.

Question 4

A mutation causes a gene to be located in a region of heterochromatin during interphase. What is the most likely effect on gene expression?

Accepted Answer

Gene expression will decrease because dense packing inhibits transcription.

Question 5

Which equation best represents the exponential decay of protein concentration due to proteasome-mediated degradation, assuming a half-life $$t_{1/2}$$?

Accepted Answer

$$C(t) = C_0$ 	imes e$$^{-kt}$$, where k$$ = \frac{\ln 2}{t_{1/2}}$$

Question 6

Alternative RNA splicing allows a single gene to:

Accepted Answer

Produce multiple mRNA variants, resulting in different protein isoforms.

Question 7

Which of the following is a direct consequence of DNA methylation in eukaryotic cells?

Accepted Answer

Long-term inactivation of genes, often associated with genomic imprinting.

Question 8

A cell is exposed to a stressor that requires rapid changes in protein levels. Which regulatory mechanism is most likely to allow the cell to quickly adjust gene expression?

Accepted Answer

Post-transcriptional regulation, such as mRNA degradation and translation initiation control.

Question 9

Which of the following best explains why liver cells and lens cells express different proteins, even though they contain the same DNA?

Accepted Answer

Differential gene expression regulated by specific combinations of control elements and available activators.

Question 10

Which of the following is NOT a function of transcription factors?

Accepted Answer

Degrading mRNA in the cytoplasm.

Question 11

A scientist discovers a regulatory protein that binds to the 5' UTR of an mRNA and prevents ribosome attachment. What process is being regulated?

Accepted Answer

Initiation of translation.

Question 12

Which of the following scenarios would most likely result in the production of a mutant phenotype, as shown in the wildtype vs. mutant fly images?

Accepted Answer

Failure to regulate gene expression during development.

Question 13

Which of the following best describes the role of the proteasome in eukaryotic cells?

Accepted Answer

It binds and degrades ubiquitinated proteins into peptides.

Question 14

Which of the following is a key difference between euchromatin and heterochromatin?

Accepted Answer

Euchromatin is loosely packed and generally transcriptionally active.

Question 15

Which of the following steps is NOT a potential control point for regulating gene expression in eukaryotic cells?

Accepted Answer

DNA replication during mitosis.

Question 16

A mutation in the enhancer region of a gene prevents activator proteins from binding. What is the most likely outcome?

Accepted Answer

Transcription of the gene will be reduced or absent.

Question 17

Which of the following best explains the concept of epigenetics?

Accepted Answer

Changes in gene expression that do not involve changes in the DNA sequence, such as DNA methylation.

Question 18

Which process is most directly responsible for the rapid degradation of mRNA in bacteria compared to eukaryotes?

Accepted Answer

Shortening of the polyA tail and removal of the 5' cap.

Question 19

Which of the following is true regarding the relationship between genome size and number of genes across species?

Accepted Answer

Genome size and gene number can vary independently; some species have large genomes but relatively few genes.

Regulation of Gene Expression in Eukaryotes

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