Q: Which equation correctly represents the hydrolysis of ONPG by β-galactosidase in a reporter assay?

$ONPG + H_2O \rightarrow o\text{-}nitrophenol + galactose$

Question 1

Which of the following best describes the primary purpose of microbial regulation in gene expression?

Accepted Answer

To conserve energy and resources by producing proteins only when needed

Question 2

Which process is the fastest mode of regulation in bacterial cells?

Accepted Answer

Post-translational regulation

Question 3

A scientist is studying a gene named 'lacZ'. According to standard nomenclature, which of the following correctly represents the protein product of this gene?

Accepted Answer

LacZ

Question 4

Which of the following is a reporter gene commonly used to quantify promoter activity in bacteria?

Accepted Answer

lacZ

Question 5

In the context of negative control of gene expression, what is the role of a repressor protein?

Accepted Answer

It inhibits transcription by binding to the operator

Question 6

Which of the following best describes the mechanism of catabolite repression in E. coli?

Accepted Answer

Transcription is activated by high levels of cAMP binding to CAP

Question 7

Which equation correctly represents the hydrolysis of ONPG by β-galactosidase in a reporter assay?

Accepted Answer

$ONPG + H_2O ightarrow o	ext{-}nitrophenol + galactose$

Question 8

Which DNA-binding domain is characterized by two α-helices connected by a short turn and is commonly found in bacterial regulatory proteins?

Accepted Answer

Helix-turn-helix (HTH)

Question 9

A mutation prevents the binding of cAMP to CAP in E. coli. What is the most likely effect on the lac operon?

Accepted Answer

Transcription of the lac operon will be greatly reduced even in the absence of glucose

Question 10

Which of the following is true regarding the stringent response in bacteria?

Accepted Answer

It is triggered by the accumulation of (p)ppGpp during amino acid starvation

Question 11

Which of the following statements about quorum sensing is correct?

Accepted Answer

It allows bacteria to coordinate gene expression based on population density

Question 12

What is the function of the response regulator in a two-component regulatory system?

Accepted Answer

It binds DNA and regulates transcription after being phosphorylated

Question 13

Which of the following best describes attenuation in the trp operon of E. coli?

Accepted Answer

Premature termination of transcription based on the availability of charged tRNA

Question 14

Which molecule is produced by RelA and is responsible for inhibiting rRNA and tRNA synthesis during the stringent response?

Accepted Answer

(p)ppGpp

Question 15

Which of the following is an example of feedback inhibition in a biosynthetic pathway?

Accepted Answer

The end product binds to the allosteric site of the first enzyme, inhibiting its activity

Question 16

Which of the following is a common covalent modifier that can regulate enzyme activity post-translationally?

Accepted Answer

Adenosine monophosphate (AMP)

Question 17

Which of the following statements about small regulatory RNAs (sRNAs) is correct?

Accepted Answer

They can base-pair with mRNA to either block or expose the ribosome-binding site

Question 18

Which protein acts as an RNA chaperone to facilitate the binding of trans-sRNAs to their target mRNAs?

Accepted Answer

Hfq

Question 19

Which of the following is true about riboswitches?

Accepted Answer

They are RNA domains that bind small molecules to control translation

Question 20

In the context of the SOS response, which DNA polymerases are involved in error-prone DNA repair?

Accepted Answer

DNA polymerases IV and V

Microbial Regulation: Mechanisms and Applications

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