Question 1

Which of the following best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

During DNA replication in bacteria, which enzyme is responsible for joining Okazaki fragments on the lagging strand?

Accepted Answer

DNA ligase

Question 3

A mutation changes a codon from $$	ext{UAC} ($$tyrosine) to $$	ext{UAA} ($$stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 4

Which of the following statements about the lac operon in E. coli is correct?

Accepted Answer

The lac operon is inducible and is only transcribed when lactose is present and glucose is absent.

Question 5

Which of the following best explains why DNA polymerase requires an RNA primer during DNA replication?

Accepted Answer

DNA polymerase can only add nucleotides to an existing 3' hydroxyl group.

Question 6

A bacterial cell is exposed to UV light, resulting in the formation of thymine dimers. Which repair mechanism is most likely to correct this damage?

Accepted Answer

Nucleotide excision repair

Question 7

In the context of gene regulation, what is the function of the operator region in an operon?

Accepted Answer

It acts as a binding site for the repressor protein to regulate transcription.

Question 8

Which of the following is an example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquires antibiotic resistance genes from another bacterium via conjugation.

Question 9

Which of the following best describes a frameshift mutation?

Accepted Answer

An insertion or deletion of nucleotides that changes the reading frame of the gene.

Question 10

Which of the following is a function of plasmids in bacteria?

Accepted Answer

They often carry genes for antibiotic resistance or metabolic enzymes.

Question 11

A scientist uses the Ames test to evaluate a chemical. Which result would indicate the chemical is a potential mutagen?

Accepted Answer

An increased number of revertant colonies compared to the control.

Question 12

Which of the following best explains the role of cyclic AMP (cAMP) in catabolite repression of the lac operon?

Accepted Answer

cAMP binds to CAP, allowing RNA polymerase to efficiently transcribe the lac operon when glucose is low.

Question 13

Which of the following is true regarding transcription and translation in prokaryotes?

Accepted Answer

Translation can begin before transcription is complete.

Question 14

A bacterial cell is found to have a mutation in the gene encoding DNA polymerase, resulting in loss of proofreading activity. What is the most likely consequence?

Accepted Answer

Increased mutation rate during DNA replication

Question 15

Which of the following best describes the function of small nuclear ribonucleoproteins (snRNPs) in eukaryotic cells?

Accepted Answer

They remove introns and splice exons together in pre-mRNA.

Question 16

Which of the following is a likely outcome of a missense mutation in a gene encoding an enzyme?

Accepted Answer

The enzyme may have altered activity due to a change in one amino acid.

Question 17

Which of the following best explains why methylation of DNA can affect gene expression?

Accepted Answer

Methylation can turn genes off by preventing transcription.

Question 18

Which of the following is a key difference between generalized and specialized transduction in bacteria?

Accepted Answer

Generalized transduction can transfer any bacterial gene, while specialized transduction transfers only specific genes.

Question 19

Which of the following best describes the role of transposons in bacterial genomes?

Accepted Answer

They are segments of DNA that can move from one location to another, sometimes carrying antibiotic resistance genes.

Question 20

A scientist observes that a bacterial strain can metabolize a new sugar after exposure to a mutagen. Which best explains how this trait could arise?

Accepted Answer

A beneficial mutation altered an enzyme, allowing metabolism of the new sugar.

Microbial Genetics: Structure, Function, and Mechanisms

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