Question 1

lacI codes for an__________,and when lacI is mutated,the lac operon is __________.

Accepted Answer

A) repressor; never expressed 
B) repressor; constitutively expressed 
C) structural gene; never expressed 
D) activator; constitutively expressed 
E) activator; never expressed 
A) repressor; never expressed 
B) repressor; constitutively expressed 
C) structural gene; never expressed 
D) activator; constitutively expressed 
E) activator; never expressed

Question 2

A constitutive mutation in the lac operon may be of several types.Name two types of constitutive mutations and explain why they are constitutive.

Accepted Answer

lacI^-is a lac operon constitutive mutatio

Question 3

What two important domains within a riboswitch involve the ligand- binding site?

Accepted Answer

A) B site and C site 
B) alpha and beta 
C) conformation and anticonformation 
D) A site and B site 
E) aptamer and expression platform 
A) B site and C site 
B) alpha and beta 
C) conformation and anticonformation 
D) A site and B site 
E) aptamer and expression platform

Question 4

When lactose is first introduced into the medium,the lac operon is not induced and thus permease isn't induced.How it is possible for lactose to enter the cell before the lac operon is induced?

Accepted Answer

While the lac operon is not induced yet,

Question 5

The cAMP- CAP complex and RNA polymerase bind more efficiently to the lac operon together than either does alone.What term is applied to this increased efficiency of binding?

Accepted Answer

The answer of The cAMP- CAP complex and RNA polymerase...

Question 6

Certain mutations in the regulator gene of the lac system in E.coli result in maximal synthesis of the lac proteins fi- galactosidase,etc.)even in the absence of the inducer lactose).Provide an explanation for this observation.

Accepted Answer

There has been a mutation in the gene th

Question 7

Which of the following terms best characterizes catabolite repression associated with the lac operon in E.coli?

Accepted Answer

A) constitutive 
B) negative control 
C) repressible system 
D) positive control 
E) inducible system 
A) constitutive 
B) negative control 
C) repressible system 
D) positive control 
E) inducible system

Question 8

When referring to attenuation in regulation of the trp operon,it would be safe to say that when there are high levels of tryptophan available to the organism,__________.

Accepted Answer

A) ribosomes are stalling during translation of the attenuator region 
B) transcriptional termination is likely 
C) translational termination is likely 
D) tryptophan is inactivating the repressor protein 
E) the trp operon is being transcribed at relatively high levels 
A) ribosomes are stalling during translation of the attenuator region 
B) transcriptional termination is likely 
C) translational termination is likely 
D) tryptophan is inactivating the repressor protein 
E) the trp operon is being transcribed at relatively high levels

Question 9

Enzymes that are continuously produced are said to have an__________expression.

Accepted Answer

A) constitutive 
B) inducible 
C) positive 
D) repressible 
E) negative 
A) constitutive 
B) inducible 
C) positive 
D) repressible 
E) negative

Question 10

The table below lists several genotypes associated with the lac operon in E.coli.For each,indicate with a "+" or a
"-" whether functional fi- galactosidase would be expected to be produced at induced levels.   I+ = wild- type repressor
I- = mutant repressor unable to bind to the operator)
Is = mutant repressor insensitive to lactose)
O+ = wild- type operator
Oc = constitutive operator insensitive to repressor)

Accepted Answer

Question 11

To translate the three enzymes of the lac operon,__________mRNA molecules is/are transcribed.

Accepted Answer

A) 3 
B) 0 
C) 2 
D) 4 
E) 1 
A) 3 
B) 0 
C) 2 
D) 4 
E) 1

Question 12

Explain how small noncoding RNAs sRNAs)can function as both a negative regulator and a positive regulator.

Accepted Answer

sRNAs can negatively regulate translatio

Question 13

What is the function of the lacY gene in the lac operon?

Accepted Answer

The lacY gene codes for permea

Question 14

What is the name of the molecule that binds to CAP to activate transcription of the lac operon?

Accepted Answer

A) galactose 
B) ATP 
C) cAMP 
D) lactose 
E) glucose 
A) galactose 
B) ATP 
C) cAMP 
D) lactose 
E) glucose

Question 15

Which binds to the operator of the lac operon?

Accepted Answer

A) permease 
B) repressor 
C) activator 
D) lactose 
E) beta galactosidase 
A) permease 
B) repressor 
C) activator 
D) lactose 
E) beta galactosidase

Question 16

In the accompanying diagram,what type of control,positive or negative,is operating? The oval structure is RNA polymerase.

Accepted Answer

The answer of In the accompanying diagram,what type of control,positive...

Question 17

What term refers to clusters of bacterial genes that are under the control of a single regulatory region?

Accepted Answer

A) prototroph 
B) allosteric 
C) attenuation 
D) autotroph 
E) operon 
A) prototroph 
B) allosteric 
C) attenuation 
D) autotroph 
E) operon

Question 18

When both lactose and glucose are available to E.coli,which part of the lac operon regulation assures that glucose will be metabolized first?

Accepted Answer

A) CAP binds to cAMP and then to the promoter only in the presence of low glucose. 
B) The repressor cannot bind to the operator in the presence of lactose. 
C) Permease allows lactose to enter the cell when lactose enters the cell. 
D) The repressor binds to the operator in the absence of lactose. 
E) RNA polymerase transcribes the lac operon to make a single RNA molecule. 
A) CAP binds to cAMP and then to the promoter only in the presence of low glucose. 
B) The repressor cannot bind to the operator in the presence of lactose. 
C) Permease allows lactose to enter the cell when lactose enters the cell. 
D) The repressor binds to the operator in the absence of lactose. 
E) RNA polymerase transcribes the lac operon to make a single RNA molecule.

Question 19

Present a detailed description of the actions of the regulatory proteins in inducible and repressible enzyme systems.

Accepted Answer

Inducible system: The repressor is norma

Question 20

The terminating "hairpin" loop occurs in the trp operon when sufficient tryptophan is present.

Accepted Answer

A) True 
 B)False

Exam 16: Regulation of Gene Expression in Bacteria

lacI codes for an__________,and when lacI is mutated,the lac operon is __________.

A constitutive mutation in the lac operon may be of several types.Name two types of constitutive mutations and explain why they are constitutive.

What two important domains within a riboswitch involve the ligand- binding site?

When lactose is first introduced into the medium,the lac operon is not induced and thus permease isn't induced.How it is possible for lactose to enter the cell before the lac operon is induced?

The cAMP- CAP complex and RNA polymerase bind more efficiently to the lac operon together than either does alone.What term is applied to this increased efficiency of binding?

Certain mutations in the regulator gene of the lac system in E.coli result in maximal synthesis of the lac proteins fi- galactosidase,etc.)even in the absence of the inducer lactose).Provide an explanation for this observation.

Which of the following terms best characterizes catabolite repression associated with the lac operon in E.coli?

When referring to attenuation in regulation of the trp operon,it would be safe to say that when there are high levels of tryptophan available to the organism,__________.

Enzymes that are continuously produced are said to have an__________expression.

To translate the three enzymes of the lac operon,__________mRNA molecules is/are transcribed.

Explain how small noncoding RNAs sRNAs)can function as both a negative regulator and a positive regulator.

What is the function of the lacY gene in the lac operon?

What is the name of the molecule that binds to CAP to activate transcription of the lac operon?

Which binds to the operator of the lac operon?

In the accompanying diagram,what type of control,positive or negative,is operating? The oval structure is RNA polymerase.

What term refers to clusters of bacterial genes that are under the control of a single regulatory region?

When both lactose and glucose are available to E.coli,which part of the lac operon regulation assures that glucose will be metabolized first?

Present a detailed description of the actions of the regulatory proteins in inducible and repressible enzyme systems.

The terminating "hairpin" loop occurs in the trp operon when sufficient tryptophan is present.

Introduction to Genetics

Mitosis and Meiosis

Mendelian Genetics

Extensions of Mendelian Genetics

Chromosome Mapping in Eukaryotes

Genetic Analysis and Mapping in Bacteria and Bacteriophages

Sex Determination and Sex Chromosomes

Chromosome Mutations: Variation in Number and Arrangement

Extranuclear Inheritance

DNA Structure and Analysis

DNA Replication and Recombination

DNA Organization in Chromosomes

The Genetic Code and Transcription

Translation and Proteins

Gene Mutation,dna Repair,and Transposition

Transcriptional Regulation in Eukaryotes

Post-Transcriptional Regulation in Eukaryotes

Epigenetic Regulation in Eukaryotes

Recombinant Dna Technology

Genomic Analysis

Applications of Genetic Engineering and Biotechnology

Developmental Genetics

Cancer Genetics

Quantitative Genetics and Multifactorial Traits

Population and Evolutionary Genetics

CRISPR and Genomic Editing

DNA Forensics

Genomics and Precision Medicine

Genetically Modified Foods

Gene Therapy

Advances in Neurogenetics: The Study of Huntington Disease

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lacI codes for an,and when lacI is mutated,the lac operon is .