Question 1

E.coli is the organism in which many _______________ mechanisms were first discovered.

Accepted Answer

gene-regulation

Question 2

Is it likely that the DNA binding sites for a repressor evolved from a common ancestor?

Accepted Answer

No.The sites are small and vary significantly from each other.Therefore,it is likely that they evolved independently.

Question 3

How does the λ repressor promote the lysogenic state?

Accepted Answer

The λ repressor binds to three binding sites in the right operator with different affinities,the highest being for O_R1.Binding is cooperative,so the likelihood of binding O_R2 increases once it has bound to O_R1.When λ repressor levels are low,the repressor binds to sites O_R1 and O_R2,stimulating the expression of the gene that encodes the λ repressor.The repressor blocks the transcription of almost all genes encoded by the virus,and thus promotes the lysogenic state.

Question 4

The λ repressor has the highest affinity for which of the DNA binding sites?

Accepted Answer

A)  OR1 
B)  OR2 
C)  OR3 
D)  OR4 
E)  It has equal affinity for all sites. 
A)  OR1 
B)  OR2 
C)  OR3 
D)  OR4 
E)  It has equal affinity for all sites.

Question 5

The twofold axis of symmetry of the lac repressor matches the symmetry of the ____________.

Accepted Answer

DNA or inv

Question 6

What is the name of a peptide containing an abundance of the amino acid residues of the type synthesized by the operon?

Accepted Answer

A)  inhibitory peptide 
B)  operon peptide 
C)  leader peptide 
D)  catabolite peptide 
E)  regulator peptide 
A)  inhibitory peptide 
B)  operon peptide 
C)  leader peptide 
D)  catabolite peptide 
E)  regulator peptide

Question 7

In which pathway is the viral genome incorporated into the bacterial DNA?

Accepted Answer

A)  attenuation 
B)  lysogenic 
C)  lytic 
D)  trp operon 
E)  None of the answers is correct. 
A)  attenuation 
B)  lysogenic 
C)  lytic 
D)  trp operon 
E)  None of the answers is correct.

Question 8

Which of the following occur in the lytic pathway of bacteriophage infection?

Accepted Answer

A)  Viral particles are released. 
B)  Viral DNA is not expressed. 
C)  Viral genome is carried with bacterial replication. 
D)  Very few viral proteins are produced. 
E)  None of the answers is correct. 
A)  Viral particles are released. 
B)  Viral DNA is not expressed. 
C)  Viral genome is carried with bacterial replication. 
D)  Very few viral proteins are produced. 
E)  None of the answers is correct.

Question 9

What are the elements included in the operon model proposed by Jacob and Monod?

Accepted Answer

Their model included a regulat

Question 10

Attenuation of the trp mRNA occurs because translation stalls while awaiting the formation of more _______________.

Accepted Answer

The answer of Attenuation of the trp mRNA occurs because...

Question 11

A chemical commonly used to induce the lac operon in laboratory experiments is

Accepted Answer

A)  lactose. 
B)  X-Gal. 
C)  IPTG. 
D)  galactose. 
E)  None of the answers is correct. 
A)  lactose. 
B)  X-Gal. 
C)  IPTG. 
D)  galactose. 
E)  None of the answers is correct.

Question 12

Explain the difference between constitutive and regulated expression.

Accepted Answer

Genes that are expressed all the time ar

Question 13

What type of chemical language allows prokaryotic cells to deduce population densities?

Accepted Answer

A)  quorum sensing 
B)  colony collapse 
C)  satellite communication 
D)  biofilm sensing 
E)  None of the answers is correct. 
A)  quorum sensing 
B)  colony collapse 
C)  satellite communication 
D)  biofilm sensing 
E)  None of the answers is correct.

Question 14

How was the interaction known as quorum sensing discovered?

Accepted Answer

When the bacteria Vibrio fischeri is gro

Question 15

What pathway involving phage λ releases approximately 100 viral particles?

Accepted Answer

A)  lysogeny 
B)  lytic pathway 
C)  exocytotic pathway 
D)  attenuation cycle 
E)  eruption event 
A)  lysogeny 
B)  lytic pathway 
C)  exocytotic pathway 
D)  attenuation cycle 
E)  eruption event

Question 16

Which of the following contributes to the attenuation of the trp mRNA transcript?

Accepted Answer

A)  high levels of tryptophan 
B)  plentiful amounts of trp tRNA 
C)  formation of a stem-loop structure at the 5' end of the attenuator region 
D)  uninterrupted synthesis of the leader peptide 
E)  All of the answers are correct. 
A)  high levels of tryptophan 
B)  plentiful amounts of trp tRNA 
C)  formation of a stem-loop structure at the 5' end of the attenuator region 
D)  uninterrupted synthesis of the leader peptide 
E)  All of the answers are correct.

Question 17

In the helix-turn-helix motif of DNA binding proteins,the amino acid side chains of one helix bind to the __________________ and the other to the _________________.

Accepted Answer

major groo

Question 18

Describe the proteins that determine whether the lytic or the lysogenic pathway is followed in the infectious cycle of the λ-phage.

Accepted Answer

Two key proteins (λ repressor and Cro)bi

Question 19

What prokaryotic mechanism for regulating transcription is employed by the trp operon?

Accepted Answer

A)  autoinduction 
B)  constitutive expression 
C)  catabolite repression 
D)  attenuation 
E)  quorum sensing 
A)  autoinduction 
B)  constitutive expression 
C)  catabolite repression 
D)  attenuation 
E)  quorum sensing

Question 20

How does the inducer affect lac operon regulation?

Accepted Answer

The repressor is normally bound to the D

Exam 31: The Control of Gene Expression in Prokaryotes

E.coli is the organism in which many _______________ mechanisms were first discovered.

Is it likely that the DNA binding sites for a repressor evolved from a common ancestor?

How does the λ repressor promote the lysogenic state?

The λ repressor has the highest affinity for which of the DNA binding sites?

The twofold axis of symmetry of the lac repressor matches the symmetry of the ____________.

What is the name of a peptide containing an abundance of the amino acid residues of the type synthesized by the operon?

In which pathway is the viral genome incorporated into the bacterial DNA?

Which of the following occur in the lytic pathway of bacteriophage infection?

What are the elements included in the operon model proposed by Jacob and Monod?

Attenuation of the trp mRNA occurs because translation stalls while awaiting the formation of more _______________.

A chemical commonly used to induce the lac operon in laboratory experiments is

Explain the difference between constitutive and regulated expression.

What type of chemical language allows prokaryotic cells to deduce population densities?

How was the interaction known as quorum sensing discovered?

What pathway involving phage λ releases approximately 100 viral particles?

Which of the following contributes to the attenuation of the trp mRNA transcript?

In the helix-turn-helix motif of DNA binding proteins,the amino acid side chains of one helix bind to the __________________ and the other to the _________________.

Describe the proteins that determine whether the lytic or the lysogenic pathway is followed in the infectious cycle of the λ-phage.

What prokaryotic mechanism for regulating transcription is employed by the trp operon?

How does the inducer affect lac operon regulation?

Biochemistry: An Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

Oxidative Phosphorylation

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

DNA Replication, repair, and Recombination

RNA Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

In the helix-turn-helix motif of DNA binding proteins,the amino acid side chains of one helix bind to the __ and the other to the _.