Question 1

Which of the following best describes the difference between a genotype and a phenotype in a bacterial cell?

Accepted Answer

Genotype refers to the set of genes in the genome, while phenotype refers to the physical and functional traits expressed by the organism.

Question 2

A scientist discovers a bacterium with a circular DNA molecule in the nucleoid and several small, independently replicating DNA molecules. What are these small DNA molecules most likely to be?

Accepted Answer

Plasmids

Question 3

Which of the following statements about DNA replication in bacteria is correct?

Accepted Answer

DNA replication is semiconservative, producing two DNA molecules each with one original and one new strand.

Question 4

Which of the following best explains why plasmids can confer survival advantages to bacteria?

Accepted Answer

Plasmids may carry genes for antibiotic resistance, virulence, or metabolic pathways that are beneficial under certain conditions.

Question 5

During transcription in prokaryotes, which of the following events occurs first?

Accepted Answer

Binding of RNA polymerase to the promoter region

Question 6

A mutation changes a codon from UAU (tyrosine) to UAA (stop codon). What type of mutation is this?

Accepted Answer

Nonsense mutation

Question 7

Which of the following is a key difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotic DNA replication has thousands of origins of replication, while prokaryotic DNA replication typically has one.

Question 8

Which of the following best describes the function of an inducible operon such as the lac operon?

Accepted Answer

It is activated by the presence of a substrate, allowing transcription of genes needed for catabolism.

Question 9

A bacterial cell is exposed to a chemical mutagen that causes the insertion of a single nucleotide into a gene. What is the most likely consequence?

Accepted Answer

A frameshift mutation, potentially altering every amino acid downstream of the insertion

Question 10

Which of the following is a real-world example of horizontal gene transfer in bacteria?

Accepted Answer

A bacterium acquiring antibiotic resistance genes from another bacterium via conjugation

Question 11

Which enzyme is responsible for removing supercoils in bacterial DNA during replication?

Accepted Answer

Gyrase

Question 12

In the context of gene regulation, what is the role of a repressor protein in a repressible operon such as the trp operon?

Accepted Answer

It binds to the operator to block transcription when the pathway product is abundant.

Question 13

Which of the following best explains why DNA methylation is important in bacteria?

Accepted Answer

It helps control gene expression, initiates DNA replication, and protects against viral infection.

Question 14

A scientist uses the Ames test to screen a chemical for mutagenicity. Which result would indicate that the chemical is a mutagen?

Accepted Answer

The chemical increases the number of revertant colonies compared to the control.

Question 15

Which of the following best describes the process of generalized transduction?

Accepted Answer

A bacteriophage transfers random DNA segments from a donor to a recipient bacterium.

Question 16

Which of the following is a function of regulatory RNA molecules such as siRNA in bacteria?

Accepted Answer

They bind to mRNA and prevent translation, thus regulating gene expression.

Question 17

A mutation in a bacterial gene results in a protein with a single amino acid change. What type of mutation is this most likely to be?

Accepted Answer

Missense mutation

Question 18

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

Accepted Answer

DNA is transcribed to RNA, which is then translated to form polypeptides.

Question 19

Which of the following is a key feature of eukaryotic mRNA processing before translation?

Accepted Answer

Addition of a 5' guanine cap and a poly-A tail, and removal of introns

Question 20

A bacterial cell is exposed to UV light, which causes the formation of thymine dimers. Which DNA repair mechanism is most likely to directly reverse this damage?

Accepted Answer

Direct repair using photolyase enzymes

Genetics in Microbiology: Structure and Function of Genomes (Chapter 7 Study Notes)

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