Question 1

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 B

Question 2

What are biofilms, and why are they medically important?

Accepted Answer

Biofilms are specialized structures formed on surfaces where many species of prokaryotes may be found. Quorum sensing appears to be important in the formation of biofilms. They are medically important because organisms within them are often quite resistant to the immune response of the host and to antibiotics.

Question 3

How was the interaction known as quorum sensing discovered?

Accepted Answer

When the bacteria Vibrio fischeri is grown at low density, the cells are not bioluminescent, but when the cell density reaches a critical level, they do bioluminesce. When V. fischeri cells are transferred to a sterile medium in which other V. fischeri had been grown to high density, they become bioluminescent, even at low density. A chemical released by the cells once the cell density reached a certain level was found to have triggered the development of the bioluminescence in the low density cells.

Question 4

The pur repressor behaves __________________ to that of the lac repressor.

Accepted Answer

in an oppo

Question 5

Which of the following is the inducer of the lac operon in cells?

Accepted Answer

A)  lactose 
B)  galactose 
C)  allolactose 
D)  glucose 
E)  isopropylthiogalactopyranoside 
A)  lactose 
B)  galactose 
C)  allolactose 
D)  glucose 
E)  isopropylthiogalactopyranoside

Question 6

What reaction is carried out by β-galactosidase?

Accepted Answer

A)  Lactose is hydrolyzed to galactose and sucrose. 
B)  Lactose is hydrolyzed to galactose and glucose. 
C)  Lactose is hydrolyzed to two molecules of glucose. 
D)  Lactose is hydrolyzed to two molecules of galactose. 
E)  None of the answers is correct. 
A)  Lactose is hydrolyzed to galactose and sucrose. 
B)  Lactose is hydrolyzed to galactose and glucose. 
C)  Lactose is hydrolyzed to two molecules of glucose. 
D)  Lactose is hydrolyzed to two molecules of galactose. 
E)  None of the answers is correct.

Question 7

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) b

Question 8

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 9

Which of the following is produced when tryptophan levels are low?

Accepted Answer

A)  162-nucleotide trp mRNA leader sequence 
B)  7000-nucleotide trp mRNA 
C)  130-nucleotide trp mRNA 
D)  162-nucleotide trp mRNA leader sequence and 7000-nucleotide trp mRNA 
E)  7000-nucleotide trp mRNA and 130-nucleotide trp mRNA 
A)  162-nucleotide trp mRNA leader sequence 
B)  7000-nucleotide trp mRNA 
C)  130-nucleotide trp mRNA 
D)  162-nucleotide trp mRNA leader sequence and 7000-nucleotide trp mRNA 
E)  7000-nucleotide trp mRNA and 130-nucleotide trp mRNA

Question 10

Briefly explain how attenuation regulates transcription.

Accepted Answer

Attenuation is a prokaryotic mechanism w

Question 11

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 12

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 13

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 14

What is the relationship between gene regulation and sequences in the genome?

Accepted Answer

It is important to remember that the gen

Question 15

How does the λ repressor promote the lysogenic state?

Accepted Answer

The λ repressor binds to three binding s

Question 16

How does the Cro protein promote the lytic state?

Accepted Answer

Cro and λ repressor both bind to three b

Question 17

CAP (catabolite activating protein) is an example of a protein that _______________ transcription.

Accepted Answer

stimulates

Question 18

What substrate forms a colored product in the presence of $\beta$-galactosidase?

Accepted Answer

A)  p-nitrophenyl galactose 
B)  Coomassie-galactose 
C)  ethidium-galactose 
D)  X-gal 
E)  None of the answers is correct. 
A)  p-nitrophenyl galactose 
B)  Coomassie-galactose 
C)  ethidium-galactose 
D)  X-gal 
E)  None of the answers is correct.

Question 19

A unit of gene expression that allows controlled and coordinated expression of a set of proteins is called a(n) __________________.

Accepted Answer

The answer of A unit of gene expression that allows...

Question 20

The lac operon contains the gene(s) for the protein(s)

Accepted Answer

A)  β-galactosidase. 
B)  permease. 
C)  transacetylase. 
D)  β-galactosidase and permease 
E)  All the answers are correct. 
A)  β-galactosidase. 
B)  permease. 
C)  transacetylase. 
D)  β-galactosidase and permease 
E)  All the answers are correct.

Exam 31: The Control of Gene Expression in Prokaryotes

What pathway involving phage λ releases approximately 100 viral particles?

What are biofilms, and why are they medically important?

How was the interaction known as quorum sensing discovered?

The pur repressor behaves __________________ to that of the lac repressor.

Which of the following is the inducer of the lac operon in cells?

What reaction is carried out by β-galactosidase?

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?

Which of the following is produced when tryptophan levels are low?

Briefly explain how attenuation regulates transcription.

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

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

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

What is the relationship between gene regulation and sequences in the genome?

How does the λ repressor promote the lysogenic state?

How does the Cro protein promote the lytic state?

CAP (catabolite activating protein) is an example of a protein that _______________ transcription.

What substrate forms a colored product in the presence of β\betaβ -galactosidase?

A unit of gene expression that allows controlled and coordinated expression of a set of proteins is called a(n) __________________.

The lac operon contains the gene(s) for the protein(s)

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

Oxidative Phosphorylation

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

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

What substrate forms a colored product in the presence of $\beta$ -galactosidase?