Question 1

Which process is depicted in the diagram showing the flow of genetic information from DNA to RNA to Protein, and what is the correct sequence of events?

Accepted Answer

Central dogma: DNA (transcription) → RNA (translation) → Protein

Question 2

In the context of bacterial genetics, what is the primary function of supercoiling in the bacterial chromosome?

Accepted Answer

To compact the DNA so it fits inside the cell and remains accessible for gene expression

Question 3

Which enzyme is responsible for relaxing supercoiling ahead of the replication fork during DNA replication in bacteria?

Accepted Answer

DNA gyrase

Question 4

During DNA replication, which strand is synthesized discontinuously, and what are the short fragments called?

Accepted Answer

Lagging strand; Okazaki fragments

Question 5

Which of the following best describes the role of the promoter in transcription?

Accepted Answer

It is the DNA sequence where RNA polymerase binds to initiate transcription

Question 6

A mutation changes a DNA sequence from TAC TTC AAA CCG ATT to TAC TTC AAC CGA TT. What type of mutation is this, and what is its likely effect?

Accepted Answer

Frameshift mutation; likely alters the reading frame and protein function

Question 7

Which of the following statements about plasmids is TRUE?

Accepted Answer

Plasmids are circular DNA molecules that often carry accessory genes, such as antibiotic resistance genes

Question 8

What is the effect of a nonsense mutation on the resulting protein?

Accepted Answer

It introduces a premature stop codon, leading to a truncated protein

Question 9

Which of the following best explains why most cells possess negatively supercoiled DNA?

Accepted Answer

Negative supercoiling makes it easier to separate the two DNA strands during replication and transcription

Question 10

Which of the following is a clinical application of genomics?

Accepted Answer

Using DNA sequencing to identify antibiotic resistance genes in pathogens

Question 11

In the lac operon, what happens when lactose is present in the environment?

Accepted Answer

Allolactose (inducer) binds to the repressor, inactivating it and allowing transcription

Question 12

Which of the following best describes the difference between vertical and horizontal gene transfer in bacteria?

Accepted Answer

Vertical gene transfer is the transfer of genes from parent to offspring; horizontal gene transfer is the transfer of genes between cells of the same generation

Question 13

Which enzyme is responsible for joining Okazaki fragments on the lagging strand during DNA replication?

Accepted Answer

DNA ligase

Question 14

What is the role of cAMP in the regulation of the lac operon?

Accepted Answer

cAMP binds to the catabolite activator protein (CAP), which then binds to the promoter and enhances transcription

Question 15

Which of the following is a function of transposons in bacterial genomes?

Accepted Answer

They move genetic material within and between DNA molecules, potentially spreading antibiotic resistance genes

Question 16

A chemical mutagen causes adenine to pair with cytosine instead of thymine. What type of mutagen is this, and what is the likely result?

Accepted Answer

Nitrous acid; base substitution mutation

Question 17

Which of the following mechanisms is used by bacteria to repair thymine dimers caused by UV radiation?

Accepted Answer

Photolyase (light-repair enzyme)

Question 18

What is the principle behind the Ames test for chemical carcinogens?

Accepted Answer

It measures the rate of reversion of a mutation in bacteria exposed to a potential mutagen

Question 19

Which of the following best describes the function of an operon in bacterial gene regulation?

Accepted Answer

A set of operator and promoter sites and the structural genes they control

Question 20

Which of the following is a post-transcriptional regulatory mechanism in bacteria?

Accepted Answer

Riboswitches in mRNA that alter translation in response to small molecules

Microbial Genetics: Structure, Function, and Regulation of Genetic Material

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