Question 1

Which of the following best describes the function of the 16S rRNA in prokaryotic translation?

Accepted Answer

It facilitates initiation by base pairing with the Shine-Dalgarno sequence and helps position mRNA on the ribosome.

Question 2

Which of the following statements about plasmids is CORRECT?

Accepted Answer

Plasmids can confer special metabolic activities, virulence, and the ability for horizontal gene transfer in bacteria.

Question 3

In the lac operon, what is the role of allolactose?

Accepted Answer

It serves as an inducer by binding to the LacI repressor, causing it to release from the operator and allowing transcription.

Question 4

Which equation correctly represents the process of peptide bond formation catalyzed by the ribosome?

Accepted Answer

$$\mathrm{Amino\ acid}_1 + \mathrm{Amino\ acid}_2 \rightarrow \mathrm{Dipeptide} + H_2O$$

Question 5

Which of the following is a key difference between transcription in bacteria and archaea?

Accepted Answer

Bacterial RNA polymerase requires sigma factors for promoter recognition, while archaeal RNA polymerase resembles eukaryotic RNA polymerase II and uses TBP and TFB.

Question 6

A mutation in the gene encoding the Rho protein in E. coli would most likely affect which process?

Accepted Answer

Rho-dependent transcription termination

Question 7

Which of the following best describes the stringent response in bacteria?

Accepted Answer

It is a global regulatory mechanism that shuts down macromolecule synthesis and activates stress survival pathways during nutrient deprivation or environmental stress.

Question 8

Which of the following is TRUE regarding quorum sensing?

Accepted Answer

It is a mechanism by which bacteria and some archaea assess their population density using autoinducers.

Question 9

Which of the following is an example of positive control of gene expression?

Accepted Answer

The activation of the maltose operon in E. coli by an activator protein that facilitates RNA polymerase binding.

Question 10

Which of the following best explains the mechanism of attenuation in the trp operon?

Accepted Answer

It relies on the formation of alternative secondary structures in the leader mRNA, which are influenced by the availability of charged tRNA^Trp.

Question 11

Which of the following is a function of heat shock proteins in bacteria?

Accepted Answer

They counteract damage from denatured proteins and help the cell recover from stress.

Question 12

Which of the following equations best represents the central dogma of molecular biology?

Accepted Answer

$$\mathrm{DNA} \xrightarrow{	ext{transcription}} \mathrm{RNA} \xrightarrow{	ext{translation}} \mathrm{Protein}$$

Question 13

Which of the following is a characteristic of global control systems in bacteria?

Accepted Answer

They can include activators, repressors, signal molecules, two-component regulatory systems, regulatory RNAs, and alternative sigma factors.

Question 14

Which of the following best describes the function of a two-component regulatory system in bacteria?

Accepted Answer

It consists of a sensor kinase and a response regulator that together modulate gene expression in response to environmental changes.

Question 15

Which of the following is TRUE about enzyme induction?

Accepted Answer

It is the production of an enzyme in response to the presence of its substrate, typically affecting catabolic enzymes.

Question 16

Which of the following is a correct statement about the role of sigma factors in bacterial transcription?

Accepted Answer

Sigma factors are subunits of RNA polymerase that recognize specific promoter sequences to initiate transcription.

Question 17

Which of the following is a likely consequence of a mutation that prevents the formation of inverted repeats in a bacterial operon?

Accepted Answer

Rho-independent (intrinsic) transcription termination would be impaired, leading to longer transcripts.

Question 18

Which of the following best describes the function of the 23S rRNA in the ribosome?

Accepted Answer

It catalyzes the peptidyl transferase reaction, forming peptide bonds during translation.

Regulation of Gene Expression and Molecular Information Flow in Microorganisms

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