Micro Chapter 14

Question 1

Regulation of gene expression often occurs
A) At the transcriptional level
B) At the translational level
C) As proteins are altered via post-translational modifications
D) All of the above

Answer 1

D

Question 2

Genes that code for enzymes involved in central metabolic pathways are called
	A)	Inducible genes
	B)	Repressible genes
	C)	Constitutive genes
	D)	Variable genes

Answer 2

C

Question 3

Genes that code for enzymes with the ability to change their levels in response to specific effector molecules are called
	A)	Inducible genes
	B)	Repressible genes
	C)	Constitutive genes
	D)	Variable genes

Answer 3

A

Question 4

An increase in Beta-galactosidase occurs in E. coli cells in response to an increase in the effector molecule
	A)	Galactose
	B)	Glucose
	C)	Lactose
	D)	Allolactose

Answer 4

D

Question 5

If the product of a biosynthetic pathway inhibits gene expression of enzymes involved in the pathway, then it is called a(n)
	A)	Inducible gene
	B)	Repressible gene
	C)	Constitutive gene
	D)	Variable gene

Answer 5

B

Question 6

Regulatory proteins often have which of the following motifs that bind with DNA?
A) Alpha helices and beta-pleated sheets
B) Helix-turn-helix and zinc fingers
C) All of the above
D) None of the above

Answer 6

B

Question 7

Which of the following is a characteristic of negative transcriptional control?
A) Exhibited by the trp operon
B) Involve activator proteins
C) Binding of the regulatory protein inhibits initiation of transcription
D) Binding of the regulatory protein promotes initiation of transcription

Answer 7

C

Question 8

Which of the following is a characteristic of positive transcriptional control?
A) Exhibited in the lac operon
B) Involve repressor proteins
C) Binding of the regulatory protein inhibits initiation of transcription
D) Binding of the regulatory protein promotes initiation of transcription

Answer 8

D

Question 9

Repressor proteins bind at the
	A)	Operator
	B)	Activator-binding sites
	C)	First structural gene of the operon
	D)	None of the above

Answer 9

A

Question 10

Activator proteins bind at the
	A)	Operator
	B)	Activator-binding sites
	C)	First structural gene of the operon
	D)	None of the above

Answer 10

B

Question 11

Regulatory proteins can control the initiation of transcription by
A) Binding the DNA in an active state to inhibit transcription
B) Binding the DNA in the presence of an inducer molecule to allow transcription
C) Binding the DNA to promote transcription unless an inhibitor is present
D) All of the above

Answer 11

D

Question 12

A group of structural genes whose expression is controlled by the same regulatory proteins is called
	A)	A regulon
	B)	An operon
	C)	A repressor
	D)	An inducer

Answer 12

B

Question 13

Which operon provides a classic example of negative transcriptional control of inducible genes?
	A)	The lac operon
	B)	The trp operon
	C)	The arabinose operon
	D)	All of the above

Answer 13

A

Question 14

Which operon provides a classic example of negative transcriptional control of repressible genes?
	A)	The lac operon
	B)	The trp operon
	C)	The arabinose operon
	D)	All of the above

Answer 14

B

Question 15

Which operon provides a classic example of transcriptional control by a regulatory protein that acts both positively and negatively?
	A)	The lac operon
	B)	The trp operon
	C)	The arabinose operon
	D)	All of the above

Answer 15

C

Question 16

Which of the following best describes the action of the lac repressor in the abundance of lactose?
A) Allolactose activates the lac repressor promoting its binding with the operator, thus inhibiting transcription
B) Allolactose inactivates the lac repressor promoting its binding with the operator, thus promoting transcription
C) Allolactose activates the lac repressor preventing its binding with the operator, thus inhibiting transcription
D) Allolactose inactivates the lac repressor preventing its binding with the operator, thus promoting transcription

Answer 16

D

Question 17

Which of the following best describes the regulation of the trp operon by the trp repressor?
A) Tryptophan binds with the trp repressor resulting in activation and inhibition of transcription
B) Tryptophan cannot bind with the trp repressor resulting in inactivation and inhibition of transcription
C) Tryptophan binds with the trp repressor resulting in activation and promotion of transcription
D) None of the above

Answer 17

A

Question 18

Which of the following best describes the activity of the arabinose operon in the presence of arabinose?
A) Arabinose binds two AraC proteins and inhibits transcription
B) Arabinose binds two AraC proteins and promotes transcription
C) Two AraC proteins interact to promote transcription
D) Two AraC proteins interact to inhibit transcription

Answer 18

B

Question 19

The most well studied example of a two-component signal transduction system is
A) The lac operon in E. coli
B) The ratio of outer membrane proteins (OmpF and OmpC) in E. coli
C) Sporulation in Bacillus subtilis
D) Phosphate uptake in nutrient limited aquatic bacteria

Answer 19

B

Question 20

Which of the following is true of attenuation?
A) Transcription is initiated but prematurely stopped
B) Structural genes are not transcribed
C) Exemplified by the trp operon
D) All of the above

Answer 20

D

Question 21

Once translation occurs in the trp operon, a decrease in tryptophan levels in the cell will produce what type of response?
A) Formation of transcription pause loop (1:2 loop) and terminator loop (3:4 loop) to stop transcription
B) Formation of an antiterminator (2:3 loop) allowing transcription to continue
C) Formation of a transcription terminator loop (3:4 loop) only to stop transcription
D) None of the above

Answer 21

B

Question 22

A specialized form of transcription attenuation that involves mRNA folding is called
	A)	A termination loop
	B)	A ribosome
	C)	A riboswitch
	D)	None of the above

Answer 22

C

Question 23

In riboswitch control of the riboflavin (rib) operon in Bacillus subtilis, abundance of flavin mononucleotide (FMN) results in
A) Binding of FMN to the rifampin (rfn) box
B) A change in mRNA folding
C) Cessation of transcription
D) All of the above

Answer 23

D

Question 24

Small RNAs (sRNAs) regulate translation by
A) Binding with regulatory proteins to promote translation
B) Binding with regulatory proteins to inhibit translation
C) Folding mRNA to prevent translation
D) Complementarily pairing to leader region of target mRNA to inhibit or promote translation

Answer 24

D

Question 25

Chemotaxis in E. coli is a result of
A) Transcription control of gene expression
B) Translation control of gene expression
C) Posttranslational regulation
D) None of the above

Answer 25

C

Question 26

A collection of operons controlled by a common regulatory protein is called a
	A)	Riboswitch
	B)	Regulon
	C)	Attenuator
	D)	Replicon

Answer 26

B

Question 27

Which of the following genes in E. coli are regulated by alternate sigma factors?
A) Genes for protection against heat shock and other stresses
B) Genes for flagellum assembly
C) Genes for nitrogen metabolism
D) All of the above

Answer 27

D

Question 28

Which of the following best describes the regulation of the lac operon under high glucose and low lactose conditions?
A) CAP is inactive, lac repressor is active, lowest level of transcription
B) CAP is inactive, lac repressor is inactive, low level of transcription
C) CAP is active, lac repressor is active, low level of transcription
D) CAP is active, lac repressor is inactive, maximal level of transcription

Answer 28

A

Question 29

When bacterial cells are starved for amino acids, they
A) Transcribe tRNA and rRNA genes abundantly
B) Translate proteins that metabolize amino acids
C) Downregulate synthesis of tRNA and rRNA
D) All of the above

Answer 29

C

Question 30

Quorum sensing, a form of cell-to-cell communication, occurs when
A) Autoinducers reach a critical level and diffuse back into the cell
B) Autoinducers activate transcriptional regulators
C) Genes for light production are expressed
D) All of the above

Answer 30

D

Question 31

Sporulation in Bacillus subtilis is controlled by
	A)	The lac operon
	B)	A riboswitch
	C)	A phosphorelay system
	D)	None of the above

Answer 31

C

Question 32

The genes primarily responsible for engulfment during sporulation of B. subtilis are
	A)	Sigma A and Sigma H
	B)	Sigma K AND Sigma G
	C)	Sigma E and Sigma F
	D)	Kin A and Kin B

Answer 32

C