Question 1

Which of the following best describes the central dogma of molecular biology as depicted in the first image?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

During bacterial translation, what is the role of peptidyl transferase as shown in the second image?

Accepted Answer

It forms peptide bonds between amino acids.

Question 3

In the lac operon (third image), what happens when lactose is present in the environment?

Accepted Answer

The repressor is inactivated by allolactose, allowing transcription of the operon.

Question 4

Which of the following best explains the regulation of the trp operon as shown in the fourth image?

Accepted Answer

The operon is repressed when tryptophan acts as a co-repressor, activating the repressor protein.

Question 5

Which process is illustrated by the movement of a transposon from one DNA site to another, as shown in the seventh image?

Accepted Answer

Transposition

Question 6

A bacterial cell acquires antibiotic resistance by direct uptake of naked DNA from its environment. Which gene transfer mechanism is this?

Accepted Answer

Transformation

Question 7

Which enzyme is responsible for recognizing and cutting specific DNA sequences, as used in recombinant DNA technology (see ninth image)?

Accepted Answer

Restriction enzyme

Question 8

In the process of bacterial conjugation (seventh image), what is required for the transfer of plasmid DNA between cells?

Accepted Answer

A sex pilus

Question 9

Which of the following mutations would most likely result in a nonfunctional protein?

Accepted Answer

Nonsense mutation

Question 10

What is the main difference between an inducible and a repressible operon?

Accepted Answer

Inducible operons are turned on by the presence of a substrate, repressible operons are turned off by the end product.

Question 11

Which of the following best describes the outcome of a frameshift mutation?

Accepted Answer

It results in the addition or deletion of a nucleotide, altering the reading frame and potentially all downstream amino acids.

Question 12

Which repair mechanism uses the undamaged DNA strand as a template to correct errors?

Accepted Answer

Excision repair

Question 13

A mutation that changes a codon from UAU (tyrosine) to UAA (stop) is classified as which type?

Accepted Answer

Nonsense mutation

Question 14

Which of the following is a key feature of bacterial gene expression that distinguishes it from eukaryotic gene expression?

Accepted Answer

Bacterial transcription and translation are coupled, occurring simultaneously.

Question 15

What is the function of the Shine-Dalgarno sequence in bacterial mRNA?

Accepted Answer

It is the site where the ribosome binds to initiate translation.

Question 16

Which of the following best describes the process of attenuation in prokaryotic gene regulation?

Accepted Answer

It is the premature termination of transcription, often regulated by the coupling of transcription and translation.

Question 17

Which of the following is true regarding plasmids used in biotechnology (see ninth and tenth images)?

Accepted Answer

Plasmids often carry antibiotic resistance genes and can be used as vectors for gene cloning.

Question 18

A bacterial cell with a mutation in the gene encoding RecA protein would most likely be deficient in which process?

Accepted Answer

Recombinational repair and the SOS response

Question 19

Which of the following best explains why a mutation that confers antibiotic resistance can rapidly spread in a bacterial population?

Accepted Answer

Selection pressure from antibiotics favors bacteria with resistance mutations, allowing them to survive and reproduce.

Question 20

Which of the following equations best represents the semi-conservative model of DNA replication?

Accepted Answer

$$	ext{dsDNA} ightarrow 	ext{dsDNA (1 old + 1 new strand)}$$

Microbial Genetics and Biotechnology: Core Concepts and Applications

Study Guide - Practice Questions