Question 1

Which of the following best describes the central dogma of molecular biology as it applies to bacteria?

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 synthesizing the majority of the new DNA strand?

Accepted Answer

DNA polymerase

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 lagging strand during bacterial DNA replication is correct?

Accepted Answer

It is synthesized in short fragments called Okazaki fragments.

Question 5

In the lac operon, what happens when lactose is present and glucose is absent?

Accepted Answer

The operon is transcribed at high levels due to the presence of cAMP-CAP complex and removal of the repressor.

Question 6

Which of the following best describes the function of tRNA during translation?

Accepted Answer

tRNA brings specific amino acids to the ribosome by matching its anticodon to the mRNA codon.

Question 7

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

Accepted Answer

In prokaryotes, transcription and translation can occur simultaneously in the cytoplasm.

Question 8

A bacterial cell is exposed to a mutagen that causes a single base insertion in a gene. What is the most likely consequence?

Accepted Answer

A frameshift mutation that alters the reading frame of the gene.

Question 9

Which of the following best explains why the genetic code is described as 'degenerate'?

Accepted Answer

Multiple codons can code for the same amino acid.

Question 10

In the context of gene regulation, what is the primary function of a repressor protein in a repressible operon?

Accepted Answer

To bind to the operator and block transcription when the corepressor is present.

Question 11

Which of the following is true regarding the directionality of DNA synthesis during replication?

Accepted Answer

DNA is synthesized in the 5' to 3' direction.

Question 12

A mutation in the promoter region of a bacterial gene most likely affects which process?

Accepted Answer

The initiation of transcription by RNA polymerase

Question 13

Which of the following best describes the role of cAMP in positive regulation of the lac operon?

Accepted Answer

cAMP binds to the CAP protein, allowing it to enhance RNA polymerase binding to the promoter.

Question 14

Which of the following is NOT a function of mRNA in bacterial cells?

Accepted Answer

Transporting amino acids to the ribosome

Question 15

A bacterial cell with a mutation in the gene encoding DNA ligase would most likely have difficulty with which aspect of DNA replication?

Accepted Answer

Joining Okazaki fragments on the lagging strand

Question 16

Which of the following scenarios best illustrates a repressible operon in bacteria?

Accepted Answer

An operon that is transcribed unless a corepressor is present to activate the repressor.

Question 17

Which of the following best describes a missense mutation?

Accepted Answer

A mutation that changes one amino acid in the protein sequence.

Question 18

In bacteria, which of the following is a likely consequence of a mutation that inactivates the operator region of an inducible operon?

Accepted Answer

The operon will be constitutively expressed, regardless of the presence of the inducer.

Question 19

Which of the following best explains why spontaneous mutations can occur in the absence of mutagens?

Accepted Answer

Errors in DNA replication can introduce changes in the genetic material.

Question 20

A bacterial cell is exposed to a chemical that specifically inhibits RNA polymerase. Which process will be directly affected first?

Accepted Answer

Transcription

Microbial Genetics: Core Concepts and Mechanisms

Study Guide - Practice Questions