Question 1

Which of the following best explains why two cells with the same genome can have different functions, such as an eye cell specialized for aerial vision and another for aquatic vision?

Accepted Answer

They express different genes due to the presence of specific transcription factors.

Question 2

In the trp operon, what is the role of tryptophan in regulating gene expression?

Accepted Answer

It acts as a corepressor that activates the repressor, shutting off transcription.

Question 3

Which of the following statements about the lac operon is correct?

Accepted Answer

The lac operon is an inducible operon that is usually off unless lactose is present.

Question 4

Which of the following best describes the effect of histone acetylation on gene expression?

Accepted Answer

It loosens chromatin structure, enhancing transcription.

Question 5

A mutation causes the repressor protein of the trp operon to be unable to bind tryptophan. What is the most likely outcome?

Accepted Answer

The operon will always be on, leading to continuous tryptophan synthesis.

Question 6

Which of the following is a key difference between repressible and inducible operons?

Accepted Answer

Repressible operons are usually on and can be turned off, while inducible operons are usually off and can be turned on.

Question 7

Which of the following mechanisms allows a single gene to code for multiple proteins in eukaryotes?

Accepted Answer

Alternative RNA splicing

Question 8

What is the role of ubiquitin in protein regulation?

Accepted Answer

It marks proteins for degradation by proteasomes.

Question 9

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

Accepted Answer

It generally reduces transcription by condensing chromatin.

Question 10

A bacterial cell is placed in an environment with high lactose and low glucose. What will happen to the lac operon?

Accepted Answer

The lac operon will be highly expressed due to high cAMP and inactive repressor.

Question 11

Which of the following is an example of epigenetic inheritance?

Accepted Answer

DNA methylation patterns that are inherited without changing the DNA sequence.

Question 12

Which of the following is true about general transcription factors in eukaryotes?

Accepted Answer

They are essential for the transcription of all protein-coding genes.

Question 13

Which of the following best explains why eukaryotic mRNA is generally more stable than prokaryotic mRNA?

Accepted Answer

Eukaryotic mRNA has a longer poly-A tail and protective 5' cap.

Question 14

Which of the following is a direct result of alternative RNA splicing?

Accepted Answer

Production of different mRNA molecules from the same primary transcript

Question 15

Which of the following is a function of an enhancer in eukaryotic gene regulation?

Accepted Answer

It serves as a distal control element that increases transcription when bound by activators.

Question 16

A scientist discovers a eukaryotic gene that is not expressed in a particular cell type. Which of the following could explain this observation?

Accepted Answer

The gene's promoter is methylated, preventing transcription.

Question 17

Which of the following best describes feedback inhibition in the context of tryptophan synthesis in bacteria?

Accepted Answer

Tryptophan inhibits the activity of the first enzyme in its biosynthetic pathway.

Question 18

Which of the following is a likely consequence if a mutation prevents the addition of a poly-A tail to eukaryotic mRNA?

Accepted Answer

The mRNA will be rapidly degraded in the cytoplasm.

Question 19

Which of the following is true regarding the regulation of translation in eukaryotic cells?

Accepted Answer

Regulatory proteins can bind to mRNA and block translation initiation.

Ch 18- Regulation of Gene Expression in Prokaryotes and Eukaryotes

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