Question 1

Which of the following best describes the role of the ribosome during translation in bacteria?

Accepted Answer

It catalyzes the formation of peptide bonds between amino acids.

Question 2

During the initiation phase of translation in bacteria, what is the correct order of events?

Accepted Answer

mRNA binds to small subunit, initiator tRNA binds to start codon, large subunit binds.

Question 3

Which site on the ribosome holds the tRNA carrying the growing polypeptide chain during elongation?

Accepted Answer

P site

Question 4

What triggers the termination of translation in bacteria?

Accepted Answer

A stop codon is reached and a release factor binds to the ribosome.

Question 5

Which of the following is a direct result of the coupling of transcription and translation in prokaryotes?

Accepted Answer

Multiple ribosomes can translate an mRNA while it is still being transcribed.

Question 6

In the lac operon, what is the function of the lacI gene product?

Accepted Answer

It encodes a repressor protein that binds to the operator to block transcription.

Question 7

What happens to the lac operon when lactose is present in the environment?

Accepted Answer

Lactose binds to the repressor, causing it to release from the operator, allowing transcription.

Question 8

A mutation in the lacI gene results in a nonfunctional repressor. What is the most likely outcome?

Accepted Answer

The lac operon will be transcribed continuously, regardless of lactose presence.

Question 9

Which of the following best describes negative control of gene expression?

Accepted Answer

A regulatory protein shuts down transcription by binding to DNA.

Question 10

In the ara operon, what is the role of the AraC protein when arabinose is present?

Accepted Answer

It acts as an activator, promoting transcription.

Question 11

Which of the following is a key difference between gene regulation in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotic gene expression is regulated at multiple levels, including chromatin remodeling and RNA processing.

Question 12

What is the effect of histone acetylation on chromatin structure and gene expression?

Accepted Answer

It relaxes chromatin, making genes more accessible for transcription.

Question 13

A researcher feeds pregnant rats a low-protein diet and observes abnormal histone modifications in their offspring. What does this experiment demonstrate?

Accepted Answer

Epigenetic changes can be influenced by environmental factors such as nutrition.

Question 14

Which of the following elements is NOT typically involved in the regulation of eukaryotic transcription?

Accepted Answer

Operator sequences

Question 15

Alternative splicing allows a single gene to:

Accepted Answer

Produce multiple different proteins.

Question 16

Which of the following best explains why eukaryotic gene expression is more complex than prokaryotic gene expression?

Accepted Answer

Eukaryotic genes are regulated at multiple levels, including chromatin structure, transcription, RNA processing, and translation.

Question 17

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

Accepted Answer

Decreased gene expression

Question 18

A mutation prevents the binding of a transcriptional activator to an enhancer in a eukaryotic cell. What is the most likely result?

Accepted Answer

Transcription of the target gene will decrease.

Question 19

Which of the following best describes the function of the mediator complex in eukaryotic transcription?

Accepted Answer

It facilitates the interaction between transcriptional activators and RNA polymerase II.

Question 20

A scientist observes that a gene is highly expressed in skeletal muscle but not in smooth muscle, even though both cell types contain the gene. What is the most likely explanation?

Accepted Answer

Alternative splicing produces different mRNAs in different tissues.

Transcriptional and Translational Regulation in Prokaryotes and Eukaryotes

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