Question 1

Which of the following statements best describes a constitutive gene?

Accepted Answer

A)  A gene that is expressed in the presence of an inducer 
B)  A gene that is expressed in the absence of a corepressor 
C)  A gene that is expressed only in the presence of lactose 
D)  A gene that is expressed continuously. 
E)  A gene that is under temporal regulation 
A)  A gene that is expressed in the presence of an inducer 
B)  A gene that is expressed in the absence of a corepressor 
C)  A gene that is expressed only in the presence of lactose 
D)  A gene that is expressed continuously. 
E)  A gene that is under temporal regulation D

Question 2

Compare how a negative repressible control mechanism and a positive repressible control mechanism work in the presence and absence of a co-repressor.

Accepted Answer

In a negative,repressible regulatory mechanism,transcription of the structural gene(s)occurs in the absence of the co-repressor,but not in its presence.When the repressor/co-repressor complex is bound to the RPBS,it prevents RNA polymerase from transcribing the structural genes.In the absence of co-repressor,free repressor cannot bind to the RPBS; thus,RNA polymerase can bind to the promoter and transcribe the structural genes.In a positive,repressible control mechanism,the product of the regulator gene,the activator,must be bound to the RPBS in order for RNA polymerase to bind to the promoter and transcribe the structural gene(s).When co-repressor is present,it forms a complex with the activator protein,and this activator/co-repressor complex is unable to bind to the RPBS; consequently,RNA polymerase cannot bind to the promoter and transcribe the structural gene(s).

Question 3

Which of the following is true about regulation of prokaryotic gene expression?

Accepted Answer

A)  Genes such as rRNAs and tRNAs, which specify housekeeping functions, can be repressed or induced as required. 
B)  Genes that encode enzymes involved in catabolic pathways are always expressed constitutively. 
C)  Genes that encode anabolic enzymes are not repressible. 
D)  Transcriptional regulation is the most common mechanism of control in prokaryotes. 
E)  Translational regulation is the most common mechanism of control in prokaryotes. 
A)  Genes such as rRNAs and tRNAs, which specify housekeeping functions, can be repressed or induced as required. 
B)  Genes that encode enzymes involved in catabolic pathways are always expressed constitutively. 
C)  Genes that encode anabolic enzymes are not repressible. 
D)  Transcriptional regulation is the most common mechanism of control in prokaryotes. 
E)  Translational regulation is the most common mechanism of control in prokaryotes. D

Question 4

What type of operon is the trp operon?

Accepted Answer

A)  Positive repressible operon 
B)  Negative repressible operon 
C)  Positive inducible operon 
D)  Negative inducible operon 
E)  Constitutive inducible operon 
A)  Positive repressible operon 
B)  Negative repressible operon 
C)  Positive inducible operon 
D)  Negative inducible operon 
E)  Constitutive inducible operon

Question 5

Regulatory fine-tuning frequently occurs at the level of translation by:
1)Modulation of the rate of polypeptide chain initiation
2)Modulation of the rate of chain elongation
3)Modulation of the amino acid sequence

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  1 and 2 
E)  All of these are correct. 
A)  1 
B)  2 
C)  3 
D)  1 and 2 
E)  All of these are correct.

Question 6

Which type of genes typically control the enzymes involved in anabolic pathways?

Accepted Answer

A)  Inducible genes 
B)  Repressible genes 
C)  Constitutive genes 
D)  Inducible genes and repressible genes 
E)  All of these are correct. 
A)  Inducible genes 
B)  Repressible genes 
C)  Constitutive genes 
D)  Inducible genes and repressible genes 
E)  All of these are correct.

Question 7

Where does the regulator bind in order to control transcription?

Accepted Answer

A)  Promoter 
B)  Operator 
C)  Regulator protein binding site 
D)  Enhancer 
E)  Silencer 
A)  Promoter 
B)  Operator 
C)  Regulator protein binding site 
D)  Enhancer 
E)  Silencer

Question 8

How is sequential gene expression controlled in bacterial viruses like E.coli phages T7 and T4 and Bacillus subtilis phage SP01?

Accepted Answer

A)  Modifying the DNA topology 
B)  Sequential binding of a series of repressor molecules 
C)  Modifying the specificity of RNA polymerase for different promoter sequences 
D)  Sequential binding of inducer molecules to the repressor 
E)  None of these are correct. 
A)  Modifying the DNA topology 
B)  Sequential binding of a series of repressor molecules 
C)  Modifying the specificity of RNA polymerase for different promoter sequences 
D)  Sequential binding of inducer molecules to the repressor 
E)  None of these are correct.

Question 9

Which of the following statements is false?

Accepted Answer

A)  In an inducible operon, free repressor binds to the operator. 
B)  In an inducible operon, free repressor cannot bind to the operator. 
C)  In a repressible operon, free repressor binds to the operator. 
D)  In an inducible operon, only a repressor-corepressor complex can bind to the operator. 
E)  In a repressible operon, only the free corepressor can bind to the operator. 
A)  In an inducible operon, free repressor binds to the operator. 
B)  In an inducible operon, free repressor cannot bind to the operator. 
C)  In a repressible operon, free repressor binds to the operator. 
D)  In an inducible operon, only a repressor-corepressor complex can bind to the operator. 
E)  In a repressible operon, only the free corepressor can bind to the operator.

Question 10

Which of the following is not a constituent of an operon?

Accepted Answer

A)  Operator 
B)  Structural genes 
C)  Promoter 
D)  Intron 
E)  All of these are correct. 
A)  Operator 
B)  Structural genes 
C)  Promoter 
D)  Intron 
E)  All of these are correct.

Question 11

In prokaryotes,genes with related functions often are present in coordinately regulated genetic units called what?

Accepted Answer

A)  Operators 
B)  Operons 
C)  Codons 
D)  Anticodons 
E)  Regulatory units 
A)  Operators 
B)  Operons 
C)  Codons 
D)  Anticodons 
E)  Regulatory units

Question 12

Which of the following genes of phage l encodes the repressor?

Accepted Answer

A)  CI 
B)  OL 
C)  OR 
D)  CI and OL 
E)  OL and OR 
A)  CI 
B)  OL 
C)  OR 
D)  CI and OL 
E)  OL and OR

Question 13

In a negative,repressible regulatory mechanism,transcription of the structural gene(s)occurs in

Accepted Answer

A)  the absence of the co-repressor, but not in its presence. 
B)  the absence of the inducer but not in its presence. 
C)  the absence or presence of the co-repressor. 
D)  the presence of the co-repressor, but not in its absence. 
E)  None of these are correct. 
A)  the absence of the co-repressor, but not in its presence. 
B)  the absence of the inducer but not in its presence. 
C)  the absence or presence of the co-repressor. 
D)  the presence of the co-repressor, but not in its absence. 
E)  None of these are correct.

Question 14

What happens when a repressor is bound to the operator?

Accepted Answer

A)  RNA polymerase is prevented from transcribing the structural genes in the operon. 
B)  RNA polymerase transcribes the structural genes in the operon. 
C)  RNA polymerase increases the rate of transcription. 
D)  RNA polymerase decreases the rate of transcription. 
E)  None of these are correct. 
A)  RNA polymerase is prevented from transcribing the structural genes in the operon. 
B)  RNA polymerase transcribes the structural genes in the operon. 
C)  RNA polymerase increases the rate of transcription. 
D)  RNA polymerase decreases the rate of transcription. 
E)  None of these are correct.

Question 15

How does attenuation help regulate gene expression in the trp operon?

Accepted Answer

Attenuation occurs by control of the ter

Question 16

Which of the following is false with regard to the operator segment in an operon?
1)Operator regions are contiguous with promoter regions.
2)Operator regions are often located between the promoters and the structural genes that they regulate.
3)Repressors bind to the operator and turn on transcription.

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  1 and 2 
E)  2 and 3 
A)  1 
B)  2 
C)  3 
D)  1 and 2 
E)  2 and 3

Question 17

Based upon what is known about the regulation of transcription,regulatory mechanisms fall into two general categories.What are these categories and how do they work to aid organisms in cellular growth?

Accepted Answer

(1)Mechanisms that involve the rapid tur

Question 18

What type of regulation occurs when the product of the regulator gene is necessary to shut off the expression of structural genes?

Accepted Answer

A)  Constitutive control 
B)  Positive control 
C)  Negative control 
D)  Feedback control 
E)  None of these are correct. 
A)  Constitutive control 
B)  Positive control 
C)  Negative control 
D)  Feedback control 
E)  None of these are correct.

Question 19

Negative autogenous regulation refers to

Accepted Answer

A)  inhibition of translation of a specific mRNA by a protein it encodes. 
B)  inhibition of transcription of a gene by a specific mRNA it encodes. 
C)  inhibition of the first enzyme of a pathway by the end product of the biosynthetic pathway. 
D)  inhibition of the synthesis of ribosomes by the accumulation of protein molecules. 
E)  inhibition of the growth of an organism by the accumulation of toxic waste products. 
A)  inhibition of translation of a specific mRNA by a protein it encodes. 
B)  inhibition of transcription of a gene by a specific mRNA it encodes. 
C)  inhibition of the first enzyme of a pathway by the end product of the biosynthetic pathway. 
D)  inhibition of the synthesis of ribosomes by the accumulation of protein molecules. 
E)  inhibition of the growth of an organism by the accumulation of toxic waste products.

Question 20

Which of the following is true about the life cycle of  ?

Accepted Answer

A)  When phage   injects the Cro protein into E. coli it enters the lytic cycle. 
B)  When phage   injects the repressor into E. coli it enters the lysogenic pathway. 
C)  Phage  enters the lytic cycle when the repressor occupies the OL and OR sites. 
D)  Phage   enters the lysogenic pathway when the Cro protein occupies the OL and OR sites. 
E)  Translation of the cro mRNA is blocked by cro antisense RNA. 
A)  When phage   injects the Cro protein into E. coli it enters the lytic cycle. 
B)  When phage   injects the repressor into E. coli it enters the lysogenic pathway. 
C)  Phage  enters the lytic cycle when the repressor occupies the OL and OR sites. 
D)  Phage   enters the lysogenic pathway when the Cro protein occupies the OL and OR sites. 
E)  Translation of the cro mRNA is blocked by cro antisense RNA.

Exam 18: Regulation Of Gene Expression In Prokaryotes

Which of the following statements best describes a constitutive gene?

Compare how a negative repressible control mechanism and a positive repressible control mechanism work in the presence and absence of a co-repressor.

Which of the following is true about regulation of prokaryotic gene expression?

What type of operon is the trp operon?

Regulatory fine-tuning frequently occurs at the level of translation by: 1)Modulation of the rate of polypeptide chain initiation 2)Modulation of the rate of chain elongation 3)Modulation of the amino acid sequence

Which type of genes typically control the enzymes involved in anabolic pathways?

Where does the regulator bind in order to control transcription?

How is sequential gene expression controlled in bacterial viruses like E.coli phages T7 and T4 and Bacillus subtilis phage SP01?

Which of the following statements is false?

Which of the following is not a constituent of an operon?

In prokaryotes,genes with related functions often are present in coordinately regulated genetic units called what?

Which of the following genes of phage l encodes the repressor?

In a negative,repressible regulatory mechanism,transcription of the structural gene(s)occurs in

What happens when a repressor is bound to the operator?

How does attenuation help regulate gene expression in the trp operon?

Based upon what is known about the regulation of transcription,regulatory mechanisms fall into two general categories.What are these categories and how do they work to aid organisms in cellular growth?

What type of regulation occurs when the product of the regulator gene is necessary to shut off the expression of structural genes?

Negative autogenous regulation refers to

Which of the following is true about the life cycle of phage?

The Science Of Genetics

Cellular Reproduction

Mendelism The Basic Principles Of Inheritance

Extensions Of Mendelism

The Chromosomal Basis Of Mendelism

Variation In Chromosome Number And Structure

Linkage,Crossing Over,And Chromosome Mapping In …

The Genetics Of Bacteria And Their Viruses

DNA And The Molecular Structure Of Chromosomes

Replication Of DNA And Chromosomes

Transcription And RNA Processing

Translation And The Genetic Code

Mutation,DNA Repair,And Recombination

The Techniques Of Molecular Genetics

Genomics

Applications Of Molecular Genetics

Transposable Genetics Elements

Regulation Of Gene Expression In Eukaryotes

The Genetic Control Of Animal Development

The Genetic Basis Of Cancer

Inheritance Of Complex Traits

Population Genetics

Evolutionary Genetics

Filters