Question 1

Which process is depicted in the diagram showing the flow from DNA to RNA to Protein, and what is the significance of this process in cellular function?

Accepted Answer

Central dogma; it describes how genetic information is transferred from DNA to RNA and then to protein, determining cell function.

Question 2

In bacteria, the chromosome is typically found in which structure, and how is the DNA organized within this structure?

Accepted Answer

Nucleoid; DNA is organized into supercoiled loops anchored by histone-like proteins.

Question 3

What is the main advantage of negative supercoiling in bacterial DNA?

Accepted Answer

It makes the DNA strands easier to separate during replication and transcription.

Question 4

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

Accepted Answer

DNA gyrase

Question 5

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

Accepted Answer

Lagging strand; Okazaki fragments

Question 6

What provides the energy for the addition of nucleotides during DNA replication?

Accepted Answer

Hydrolysis of two phosphate groups from nucleoside triphosphates ($$	ext{dNTP} ightarrow 	ext{dNMP} + 2	ext{P}_i)$$

Question 7

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

Accepted Answer

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

Question 8

In the genetic code, what is the significance of the codon AUG?

Accepted Answer

It serves as the start codon and codes for methionine.

Question 9

Which of the following statements about the lac operon is correct?

Accepted Answer

It is an inducible operon that is turned on in the presence of lactose.

Question 10

How does cAMP regulate the lac operon in E. coli?

Accepted Answer

cAMP binds to CAP, which then binds to the promoter to enhance transcription when glucose is scarce.

Question 11

A mutation that results in a premature stop codon is called:

Accepted Answer

A nonsense mutation

Question 12

Which repair mechanism uses visible light to separate UV-induced thymine dimers?

Accepted Answer

Photolyase-mediated light repair

Question 13

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

Accepted Answer

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

Question 14

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

Accepted Answer

Transfer of a plasmid from one cell to another via conjugation

Question 15

What is the function of transposase in transposons?

Accepted Answer

It cuts and reseals DNA, allowing the transposon to move within the genome.

Question 16

Which type of gene transfer involves the uptake of naked DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 17

A frameshift mutation is most likely to result from which of the following?

Accepted Answer

Insertion or deletion of one or more nucleotide pairs

Question 18

Which of the following best describes the difference between plasmids and chromosomes in bacteria?

Accepted Answer

Plasmids carry accessory genes and replicate independently; chromosomes carry essential genes.

Question 19

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

Accepted Answer

microRNAs (miRNAs) base pair with mRNA, leading to its degradation and preventing protein synthesis.

Question 20

How do mutations and genetic recombination contribute to evolution in bacteria?

Accepted Answer

They create genetic diversity, which provides material for natural selection to act upon.

Microbial Genetics: Structure, Replication, and Expression of Bacterial Genomes

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