Question 1

Why do lacOC mutants express in cis-dominant and not in transdominant fashion?

Accepted Answer

Because in this mutant,the repressor can

Question 2

In the lac operon in E.coli,a nonsense mutation in the ________ gene will result in a loss of β-galactosidase activity in the cell.

Accepted Answer

A) lacZ 
B) lacI 
C) lacY 
D) Both A and B 
E) All of these 
A) lacZ 
B) lacI 
C) lacY 
D) Both A and B 
E) All of these

Question 3

Attenuation of the trp operon fails to occur when

Accepted Answer

A) a lack of tryptophan causes stalling of ribosomes on the leader sequence of the RNA. 
B) an RNA stem-loop forms that allows transcription to continue. 
C) an RNA stem-loop that causes transcription to terminate fails to form. 
D) the cell has enough tryptophan. 
E) the operator is mutated. 
A) a lack of tryptophan causes stalling of ribosomes on the leader sequence of the RNA. 
B) an RNA stem-loop forms that allows transcription to continue. 
C) an RNA stem-loop that causes transcription to terminate fails to form. 
D) the cell has enough tryptophan. 
E) the operator is mutated.

Question 4

What effect would mutational damage of the following genes or gene regions have on the induction of an integrated lambda phage virus?
a.damage to the cI gene
b.damage to the cro gene
c.damage to the xis gene

Accepted Answer

(a)The cI gene encodes the lambda repres

Question 5

The inducer of the lac operon is

Accepted Answer

A) galactose. 
B) glucose. 
C) allolactose. 
D) repressor protein. 
E) permease. 
A) galactose. 
B) glucose. 
C) allolactose. 
D) repressor protein. 
E) permease.

Question 6

Which positive regulatory protein is required for the production of phage coat protein in lambda?

Accepted Answer

A) CI 
B) Cro 
C) N 
D) Q 
E) None of these 
A) CI 
B) Cro 
C) N 
D) Q 
E) None of these

Question 7

What selective pressures are likely to have led to the evolution of regulatory systems like operons? Why not simply express these genes continuously?

Accepted Answer

Continual production of unnece

Question 8

The use of CAP- cAMP complex as a positive regulator is specific to the lac operon.

Accepted Answer

A) True 
 B)False

Question 9

In terms of regulation of gene expression,tryptophan and allolactose are examples of ________ molecules.

Accepted Answer

A) repressor 
B) effector 
C) inducer 
D) operator 
E) terminator 
A) repressor 
B) effector 
C) inducer 
D) operator 
E) terminator

Question 10

Give an overview of the mechanism by which ultraviolet radiation induces the lytic pathway in lambda phage.

Accepted Answer

The DNA damage that accompanies UV irrad

Question 11

Attenuation in trp gene regulation is accomplished by

Accepted Answer

A) reducing permeability of tryptophan,the effector molecule. 
B) blocking expression of trp mRNA. 
C) formation of secondary mRNA structures in the leader region. 
D) binding with RNA polymerase. 
E) repression of the trp operator. 
A) reducing permeability of tryptophan,the effector molecule. 
B) blocking expression of trp mRNA. 
C) formation of secondary mRNA structures in the leader region. 
D) binding with RNA polymerase. 
E) repression of the trp operator.

Question 12

In bacteriophage lambda,the establishment of lysogeny requires the protein product of which gene?

Accepted Answer

A) N 
B) cII 
C) cIII 
D) B and C only 
E) A,B,and C 
A) N 
B) cII 
C) cIII 
D) B and C only 
E) A,B,and C

Question 13

Briefly define what is meant by negative and positive control of the lac operon.

Accepted Answer

In negative control,the repressor protei

Question 14

Contrast negative (repressor)and positive (CAP)control in the lac operon.

Accepted Answer

Under negative control,transcription of

Question 15

A constitutive gene is a gene that is occasionally expressed.

Accepted Answer

A) True 
 B)False

Question 16

What is the underlying reason that a lambda phage would need to switch from the lysogenic state to the lytic state?

Accepted Answer

A) To have its genome replicated 
B) To kill its host cell 
C) To make more of the Cro protein 
D) To be more efficient in its use of resources 
E) To escape an endangered host cell 
A) To have its genome replicated 
B) To kill its host cell 
C) To make more of the Cro protein 
D) To be more efficient in its use of resources 
E) To escape an endangered host cell

Question 17

The order of the structural genes in the lac operon is

Accepted Answer

A) 5'-lacY-lacZ-lacA-3'. 
B) 3'-lacZ-lacY-lacA-5'. 
C) 5'-lacZ-lacY-lacA-3'. 
D) 3'-lacY-lacA-lacZ-5'. 
E) 5'-lacA-lacY-lacZ-3'. 
A) 5'-lacY-lacZ-lacA-3'. 
B) 3'-lacZ-lacY-lacA-5'. 
C) 5'-lacZ-lacY-lacA-3'. 
D) 3'-lacY-lacA-lacZ-5'. 
E) 5'-lacA-lacY-lacZ-3'.

Question 18

At the molecular level,how do proteins like repressors bind to DNA? How can binding affinities be increased or decreased?

Accepted Answer

Protein-nucleic acid interaction is medi

Question 19

The interaction between allolactose and the repressor protein results in a shape change known as a(n)

Accepted Answer

A) isomer. 
B) mutation. 
C) enantiomer. 
D) allosteric shift. 
E) transformant. 
A) isomer. 
B) mutation. 
C) enantiomer. 
D) allosteric shift. 
E) transformant.

Question 20

To maintain lysogeny in lambda,which of the following needs to occur?

Accepted Answer

A) Binding of repressor protein to OL 
B) Binding of repressor protein to OR 
C) Inactivation of PL 
D) Inactivation of PR 
E) All of these 
A) Binding of repressor protein to OL 
B) Binding of repressor protein to OR 
C) Inactivation of PL 
D) Inactivation of PR 
E) All of these

Exam 17: Regulation of Gene Expression in Bacteria and Bacteriophages

Why do lacOC mutants express in cis-dominant and not in transdominant fashion?

In the lac operon in E.coli,a nonsense mutation in the ________ gene will result in a loss of β-galactosidase activity in the cell.

Attenuation of the trp operon fails to occur when

What effect would mutational damage of the following genes or gene regions have on the induction of an integrated lambda phage virus? a.damage to the cI gene b.damage to the cro gene c.damage to the xis gene

The inducer of the lac operon is

Which positive regulatory protein is required for the production of phage coat protein in lambda?

What selective pressures are likely to have led to the evolution of regulatory systems like operons? Why not simply express these genes continuously?

The use of CAP- cAMP complex as a positive regulator is specific to the lac operon.

In terms of regulation of gene expression,tryptophan and allolactose are examples of ________ molecules.

Give an overview of the mechanism by which ultraviolet radiation induces the lytic pathway in lambda phage.

Attenuation in trp gene regulation is accomplished by

In bacteriophage lambda,the establishment of lysogeny requires the protein product of which gene?

Briefly define what is meant by negative and positive control of the lac operon.

Contrast negative (repressor)and positive (CAP)control in the lac operon.

A constitutive gene is a gene that is occasionally expressed.

What is the underlying reason that a lambda phage would need to switch from the lysogenic state to the lytic state?

The order of the structural genes in the lac operon is

At the molecular level,how do proteins like repressors bind to DNA? How can binding affinities be increased or decreased?

The interaction between allolactose and the repressor protein results in a shape change known as a(n)

To maintain lysogeny in lambda,which of the following needs to occur?

Genetics: An Introduction

DNA: The Genetic Material

DNA Replication

Gene Function

Gene Expression: Transcription

Gene Expression: Translation

Dna Mutation, DNA Repair, and Transposable Elements

Genomics: The Mapping and Sequencing of Genomes

Functional and Comparative Genomics

Recombinant DNA Technology

Mendelian Genetics

Chromosomal Basis of Inheritance

Extensions of and Deviations From Mendelian Genetic Principles

Genetic Mapping in Eukaryotes

Genetics of Bacteria and Bacteriophages

Variations in Chromosome Structure and Number

Regulation of Gene Expression in Eukaryotes

Genetic Analysis of Development

Genetics of Cancer

Population Genetics

Quantitative Genetics

Molecular Evolution

Filters

Why do lacO^C mutants express in cis-dominant and not in transdominant fashion?