Question 1

Which enzyme is responsible for unzipping the DNA helix during replication by breaking hydrogen bonds between nitrogenous bases?

Accepted Answer

Helicase

Question 2

Why is the origin of replication in prokaryotic chromosomes typically AT-rich?

Accepted Answer

AT base pairs form fewer hydrogen bonds, requiring less energy to separate.

Question 3

During DNA replication, why must the lagging strand be synthesized in fragments (Okazaki fragments)?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the 5' to 3' direction.

Question 4

What is the role of primase during DNA replication?

Accepted Answer

It synthesizes short RNA primers to provide a starting point for DNA polymerase.

Question 5

Which enzyme removes RNA primers and replaces them with DNA nucleotides during replication?

Accepted Answer

DNA polymerase I

Question 6

What is the Central Dogma of molecular biology?

Accepted Answer

The pathway from DNA to RNA to protein.

Question 7

During transcription, in which direction does RNA polymerase synthesize the mRNA transcript?

Accepted Answer

5' to 3'

Question 8

What is the function of the sigma factor in prokaryotic transcription?

Accepted Answer

It recruits RNA polymerase to the promoter region.

Question 9

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

Accepted Answer

It acts as a translator of the mRNA code into protein.

Question 10

What is the start codon in translation, and what is special about it in bacteria?

Accepted Answer

AUG; it codes for formyl-methionine in bacteria.

Question 11

Why is it beneficial that multiple codons can code for the same amino acid?

Accepted Answer

It reduces the impact of point mutations.

Question 12

Which of the following statements about prokaryotic gene expression is TRUE?

Accepted Answer

Transcription and translation occur simultaneously.

Question 13

What is an operon in prokaryotic gene regulation?

Accepted Answer

A set of genes regulated as a single unit.

Question 14

How does the presence of lactose affect the lac operon in E. coli?

Accepted Answer

Lactose binds to the repressor, inactivating it and allowing transcription.

Question 15

Which type of mutation results in a premature stop codon?

Accepted Answer

Nonsense mutation

Question 16

A frameshift mutation is most likely caused by:

Accepted Answer

Insertion or deletion of one or more bases

Question 17

Which DNA repair mechanism locates and repairs mismatched nucleotides that were not corrected by DNA polymerase?

Accepted Answer

Mismatch repair

Question 18

What is genetic recombination in bacteria?

Accepted Answer

The exchange or insertion of DNA segments between donor and recipient cells.

Question 19

Which horizontal gene transfer mechanism in bacteria requires direct cell-to-cell contact and is mediated by plasmids?

Accepted Answer

Conjugation

Question 20

A mutation that does not change the amino acid sequence of a protein is called:

Accepted Answer

Silent mutation

Microbial Genetics: DNA Replication, Transcription, Translation, Regulation, Mutations, and Recombination

Study Guide - Practice Questions