Question 1

Which of the following best describes constitutive transcription in prokaryotes?

Accepted Answer

Transcription that occurs at constant levels regardless of external conditions

Question 2

A transcription factor in prokaryotes typically has which two functional domains?

Accepted Answer

Regulatory domain and DNA binding domain

Question 3

In a negatively inducible system, what is the role of the repressor protein?

Accepted Answer

It blocks transcription by binding DNA unless an inducer is present

Question 4

Which equation best represents the relationship between transcription rate ($$R) $$and the presence of an activator ($$A) in a $$positively regulated system?

Accepted Answer

$$R = k 	imes [A]$$

Question 5

What is the function of an operator sequence in prokaryotic transcription regulation?

Accepted Answer

It is a cis-regulatory element that binds transcriptional repressors or activators

Question 6

Which scenario describes positively inducible transcription?

Accepted Answer

An activator protein binds DNA only when an effector molecule is present, allowing transcription

Question 7

In a negatively repressible system, what happens when the effector molecule is absent?

Accepted Answer

The repressor does not bind DNA, allowing transcription to occur

Question 8

Which of the following is true about operons in bacteria?

Accepted Answer

Operons allow coordinated regulation of multiple genes with related functions

Question 9

A transcription factor binds a specific DNA sequence near a gene's promoter. What is the most likely effect?

Accepted Answer

It can either activate or repress transcription depending on its regulatory domain

Question 10

Which of the following best describes the role of the helix-turn-helix motif in transcription factors?

Accepted Answer

It is a structural motif that allows specific binding to DNA sequences

Question 11

In a polycistronic operon, what is the significance of multiple Shine-Dalgarno sequences?

Accepted Answer

They allow simultaneous translation of all coding sequences from a single mRNA

Question 12

Which of the following is an example of a real-world application of transcriptional regulation in bacteria?

Accepted Answer

The lac operon allows E. coli to metabolize lactose only when it is present

Question 13

Which statement about transcriptional regulation is correct?

Accepted Answer

Transcriptional regulation can be positive or negative depending on the transcription factor's role

Question 14

If a gene is under negative inducible control, which condition will result in transcription?

Accepted Answer

An inducer binds the repressor, causing it to release from DNA

Question 15

Which of the following best explains why multiple genes in an operon can be regulated together?

Accepted Answer

They share a common promoter and regulatory sequences

Question 16

A mutation in the operator sequence of an operon prevents repressor binding. What is the most likely outcome?

Accepted Answer

Transcription of the operon will be constitutive

Question 17

Which formula represents the effect of a repressor ($$R) on $$transcription rate ($$T) in a $$negatively regulated system?

Accepted Answer

$$T = T_{max} - k 	imes [R]$$

Question 18

Which of the following is NOT a mechanism of regulated transcription in prokaryotes?

Accepted Answer

RNA polymerase binding to operator

Question 19

Which statement about the regulatory domain of a transcription factor is correct?

Accepted Answer

It interacts with other molecules to regulate transcription

Question 20

In a positively repressible system, what is the effect of an inhibitor compound binding to the activator protein?

Accepted Answer

It prevents the activator from binding DNA, stopping transcription

Regulation of Prokaryotic Transcription: Mechanisms and Concepts

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