Deck 11: Regulation of Gene Expression

Question 1

Expression of genes that are constitutive is:

A)regulated by repression.
B)unregulated.
C)regulated by induction.
D)regulated by activation.
E)regulated by attenuation.

Answer 1

B

Question 2

What does sigma factor helps the RNA polymerase do?

A)Assemble tRNA subunits.
B)Bind to activator proteins.
C)Attach the ribosomal subunits.
D)Identify the promoter region of a gene.
E)Release from the transcribed DNA.

Answer 2

D

Question 3

Cyclic AMP concentrations within an E.coli cell are high.When will lactose breakdown occur?

A)when glucose and lactose are simultaneously added to the medium
B)when glucose is added to the medium
C)when lactose is added to the medium
D)when glucose and allolactose are simultaneously added to the medium
E)when lactose and allolactose are simultaneously added to the medium

Answer 3

C

Question 4

The catabolite activator protein (CAP)activates transcription of the lac operon when it binds this coactivator.

A)lactose
B)glucose
C)cyclic-AMP
D)ATP
E)allolactose

Question 5

Isopropyl β-d-1- thiogalactopyranoside (IPTG),a lactose analog,acts as an inducer of the lac operon.What is its mode of action?

A)It functions as a co-activator of gene expression.
B)It inactivates the LacI repressor protein.
C)It activates the enzyme β-galactosidase.
D)It binds the RNAP for enhanced binding to the promoter.
E)It binds to the operator to enhance transcription initiation.

Question 6

During negative regulation of gene expression the repressor protein binds to the operator to inhibit transcription.What is the effector molecule that controls the activity of the repressor protein called?

A)corepressor
B)inducer
C)activator
D)corepressor or inducer
E)corepressor or activator

Question 7

Which is true of catabolite repression?

A)It results in diauxic growth.
B)It results in decreased growth rates.
C)It results in increased growth rates.
D)It occurs because of the toxicity of certain chemicals.
E)It only occurs when lactose is present.

Question 8

Which of these is required for transcription that is regulated by positive control?

A)activator protein
B)repressor protein
C)inducer protein
D)attenuator protein
E)DNA polymerase.

Question 9

When does repression of the lac operon occur?

A)When allolactose binds to the operator region.
B)When allolactose binds to the repressor protein.
C)When the repressor protein binds to the operator region.
D)When allolactose binds to β-galactosidase.
E)When the repressor protein binds to the promoter.

Question 10

The most commonly observed promoter sequence seen in an organism is known as the :

A)TATA box
B)-35 region
C)Consensus sequence
D)Shine Dalgarno sequence
E)None is a correct choice

Question 11

Tryptophan has the molecular property of:

A)being able to bind directly to DNA
B)acting as an activator
C)acting as an inducer
D)acting as a repressor
E)acting as a co-repressor

Question 12

Mutants that constitutively expressed β-galactosidase were placed into two different groups.Where were the mutations for constitutive expression located?

A)In either the lacZ or lacI genes.
B)In either the lacZ or lacY genes.
C)In either the lacZ gene or operator region.
D)In either the lacI or lacY genes.
E)In either the lacI gene or operator region.

Question 13

Which of these controls the expression of the lac operon?

A)An activator protein only.
B)An attenuation mechanism.
C)A repressor protein only.
D)Both repression and activation mechanisms.
E)Both repression and attenuation mechanisms.

Question 14

The term for a large group of genes whose expression is under the control of a single regulatory system.

A)operon
B)super operon
C)regulon
D)transcriptome
E)biome

Question 15

The use of sigma factor by RNAP for promoter identification is a type of

A)induction.
B)global regulation.
C)activation.
D)attenuation.
E)quorum sensing.

Question 16

How will E.coli growing in a medium containing both lactose and glucose react?

A)By preferentially utilizing lactose first.
B)By preferentially utilizing glucose first.
C)By utilizing both at the same time.
D)Neither compound will be utilized for growth.
E)One will sometimes be utilized over the other.

Question 17

What is an effector molecule?

A)A protein that binds to an operator region of a gene.
B)An activator protein for gene expression.
C)A small RNA molecule that inhibits translation of mRNA.
D)A small molecule that binds to an enzyme to regulate its activity.
E)A small molecule that binds to the operator region of a gene.

Question 18

A mutation in the lacI gene results in an active repressor protein that can no longer bind allolactose.Which would be true of the phenotype of the mutant strain?

A)It would be constitutive for β-galactosidase expression.
B)It would overexpress lacZ.
C)It would be the same as the wild-type strain.
D)It would repress β-galactosidase when lactose is present.
E)It would be overexpress β-galactosidase when lactose is present.

Question 19

What is a "reporter gene"?

A)A gene that is expressed under adverse environmental conditions.
B)The fusion of two different structural genes.
C)The fusion of a gene of interest to a regulatable promoter.
D)The fusion of a promoter region of interest to a gene whose product can easily be measured.
E)A gene whose product can easily be measured.

Question 20

One pair of terms does not fit the pattern seen with the others.Identify the mismatch:

A)activator,repressor
B)activator binding site,operator
C)inducer,corepressor
D)promoter,inducer
E)all are correctly paired

Question 21

Sigma-70 allows E.coli RNA polymerase to recognize:

A)a -12 and -35 region upstream of the transcribed region of a gene
B)a -12 and -24 region upstream of the transcribed region of a gene
C)a -10 and -35 region downstream of the transcribed region of a gene
D)a -10 and -35 region upstream of the transcribed region of a gene
E)a -24 and -35 region upstream of the coding region of a gene

Question 22

Identify the gene whose product is required for luciferase formation:

A)luxI
B)luxD
C)luxR
D)luxB
E)none is a correct choice

Question 23

A Vibrio fischeri mutant that produces light even at low cell densityhas been identified.In which gene is the mutation most likely to have occurred?

A)luxA
B)luxD
C)luxR
D)luxB
E)none is a correct choice

Question 24

Which sigma factor associates with RNA polymerase during low temperatures?

A)sigma 70
B)sigma 35
C)sigma 38
D)sigma 54
E)sigma 32

Question 25

Which sigma factor associates with RNA polymerase during high temperatures?

A)sigma 70
B)sigma 35
C)sigma 38
D)sigma 54
E)sigma 32

Question 26

Attenuation is a regulator mechanism in bacteria that relies on:

A)the inactivation of a repressor protein.
B)the activation of an activator protein.
C)transcription and translation occurring simultaneously.
D)transcription termination occurring by a rho-dependent mechanism.
E)translation termination occurring at a stop codon.

Question 27

Small non-coding RNA molecules (sRNA)affect gene expression at the level of:

A)transcription initiation.
B)transcription termination.
C)protein activity.
D)transcription elongation
E)transcription activation.

Question 28

Which factors are required and sufficient for nitrogen fixation in E.coli?

A)RNA polymerase,sigma-70,ATP
B)RNA polymerase,sigma-35,ATP
C)RNA polymerase,sigma-54,ATP
D)RNA polymerase,sigma-32,ATP
E)Additional proteins are required

Question 29

How is quorum sensing,a type of cell to cell communication,mediated?

A)By direct cell contact.
B)By transfer of genetic information.
C)By chemical signaling.
D)By two-component regulation.
E)By an induction mechanism.

Question 30

Once the autoinducer excreted by Vibrio fischeri reaches a critical concentration,it is able to diffuse back into the cell.What is its next action?

A)Bind to the bacterial luciferase to produce luminescence.
B)Inactivate a transcriptional repressor to allow transcription of the lux genes.
C)Bind to a transcriptional activator protein to activate transcription of the lux genes.
D)Be cleaved by a protease to produce luminescence.
E)Bind to the promoter to enhance transcription of the lux genes.

Question 31

A mechanism of controlling gene expression whichh will not be observed in eukaryal cells:

A)regulated by repression.
B)unregulated.
C)regulated by induction.
D)regulated by activation.
E)regulated by attenuation.

Question 32

Which of the following is not an example of a regulon?

A)SOS system
B)lac operon
C)Catabolite repression
D)Heat shock protein activation
E)All are examples of regulons

Question 33

Post-initiation control of gene expression can be accomplished by:

A)sRNAs
B)siRNAs
C)miRNA
D)asRNA
E)all are correct

Question 34

Untranslated types of RNA include

A)mRNA
B)tRNA
C)rRNA
D)sRNA
E)xRNA

Question 35

Identify the gene whose product is required for luciferase substrate formation:

A)luxI
B)luxD
C)luxA
D)luxB
E)none is a correct choice

Question 36

Which of these might be consequences of a recA mutation in the absence of DNA damage?

A)too much SOS response causing increased mutation within the genome
B)too little SOS response causing increased mutation within the genome
C)too much SOS response causing reduced mutation within the genome
D)too little SOS response causing reduced mutation within the genome
E)none of these would be a consequence of a recA mutation

Question 37

Which sigma factor associates with RNA polymerase during the expression of flagellar genes?

A)sigma 70
B)sigma 35
C)sigma 38
D)sigma 54
E)sigma 28

Question 38

Antisense RNA control of gene expression can be accomplished by:

A)sRNAs
B)siRNAs
C)miRNA
D)asRNA
E)all are correct

Question 39

Which autoinducer is used by many Gram-negative bacteria?

A)a homoserine lactone derivative
B)an activator protein
C)a repressor protein
D)a metabolic intermediate
E)allolactose

Question 40

Identify the gene encoding autoinducer in the lux operon:

A)luxI
B)luxR
C)luxA
D)luxB
E)none is a correct choice

Question 41

Which component of the two-component regulatory system frequently senses changes in the external environment?

A)repressor protein
B)activator protein
C)histidine kinase
D)response regulator
E)transport protein

Question 42

RNA transcriptional control that is achieved through mRNA secondary structure modification relies upon: (Select all that apply)

A)competition between different regions able to form stem-loop structures
B)formation or lack of formation of the terminator hairpin structure
C)single stranded RNA's ability to form hairpin structures
D)Shine Dalgarno sequence sequestration
E)None is a correct choice

Question 43

How is chemotaxis regulated?

A)By increased gene expression.
B)By decreased gene expression.
C)By a series of signal transduction events.
D)By allosteric enzymes.
E)By an induction-type mechanism.

Question 44

Untranslated types of RNA include

A)mRNA
B)tRNA
C)rRNA
D)sRNA
E)xRNA

Question 45

What would characterize the phenotype of a CheB mutant?

A)loss of motility.
B)constant tumbling.
C)smooth swimming.
D)inability to sense certain chemicals.
E)movement toward repellents and away from attractants.

Question 46

If a frameshift mutation in a trp operon structural gene occurred,what likely outcome would be observed? (Select all that apply)

A)constitutive gene expression
B)constant repression of the operon
C)no protein binding at the operator
D)no protein binding at the promoter
E)none is a correct choice

Question 47

Which of these is typically involved in a two-component regulatory system?

A)Histidine kinase and a response regulator.
B)Repressor protein and an activator protein.
C)Repressor protein and a co-repressor.
D)An activator protein and a co-activator.
E)A repressor protein and an inducer.

Question 48

What is the function of methyl-accepting chemotaxis proteins (MCPs)?

A)To phosphorylate CheY.
B)To control the direction of flagellar rotation.
C)To dephosphorylate CheY.
D)To sense the presence of a specific chemical.
E)To drive the flagellum motors.

Question 49

Bacteria with CheA AND CheY mutations will tumble on average:

A)every two seconds when attractant is not present
B)every two seconds when attractant is present
C)every ten seconds when attractant is not present
D)every ten seconds when attractant is present
E)none is a correct estimate

Question 50

Identify mechanisms that can reduce functional enzyme levels.(Select all that apply)

A)Phosphorylation
B)Methylation
C)Acetylation
D)mRNA synthesis inhibition
E)translation inhibition

Question 51

Promoter sequence deviation from the consensus may result in: (Select all that apply)

A)reduced transcription
B)increased transcription
C)no change in transcription
D)loss of translation
E)post-translational changes

Question 52

The transfer of T-DNA into a plant cell by Agrobacterium tumefaciens is a highly regulated process.This process only occurs if a plant becomes wounded and excretes various compounds that are detected by A.tumefaciens for expression of its virulence genes.Regulation of virulence gene expression is under the control of which type of system?

A)A two-component system.
B)An inducer/repressor system.
C)An activator/co-activator system.
D)A co-repressor/repressor system.
E)A repressor/co-activator system.

Question 53

Identify mechanisms that can reduce enzyme function.(Select all that apply)

A)Phosphorylation
B)Methylation
C)Acetylation
D)mRNA synthesis inhibition
E)translation inhibition

Question 54

Expression of genes that are inducible is: (Select all that apply)

A)regulated by repression.
B)unregulated.
C)regulated by induction.
D)regulated by activation.
E)regulated by phosphorylation.

Question 55

What would characterize the phenotype of a CheW mutant?

A)loss of motility.
B)constant tumbling.
C)smooth swimming.
D)inability to sense certain chemicals.
E)movement toward repellents and away from attractants.

Question 56

Identify mechanisms that can switch off gene expression.(Select all that apply)

A)Phosphorylation
B)Methylation
C)Acetylation
D)mRNA synthesis inhibition
E)translation inhibition

Question 57

Heat shock protein protection arises because: (Select all that apply)

A)their usually short half-life is reduced even further during high temperatures since all proteins in the cell are unfolding
B)they are particularly thermostable
C)the sigma factor which regulates their synthesis is more likely to be expressed at high temperature
D)competition with other unfolder peptides during growth at high temperatures extends their half life
E)all are correct explanations for the protection

Question 58

LexA protein is cleaved when increased quantities of single stranded DNA are detected by the RecA protein complex.What circumstances might culminate in LexA cleavage and SOS response induction? (Select all that apply)

A)damage by UV light
B)damge by gamma radiation
C)mutations in DNA polymerase which decrease its rate of DNA synthesis
D)transposon activity
E)plasmid acquisition

Question 59

What would characterize the phenotype of an MCP mutant?

A)loss of motility.
B)constant tumbling.
C)smooth swimming.
D)inability to sense certain chemicals.
E)movement toward repellents and away from attractants.

Question 60

What would characterize the phenotype of a CheY mutant?

A)Loss of motility.
B)Constant tumbling.
C)Constant smooth swimming.
D)Inability to sense certain chemicals.
E)Movement toward repellents and away from attractants.

Question 61

Which of these observations were essential in establishing the signal transduction pathway used for expression of A.tumefaciens virulence genes? (Select all that apply)

A)(VirA + VirG + radiolabled dATP)yields radiolableled VirA
B)(VirA + VirG + radiolabled dATP)yields radiolableled VirG
C)( VirG + radiolabled dATP)yields radiolableled VirG
D)( VirA + radiolabled dATP)yields radiolableled VirA
E)(radiolableled VirA + VirG)yields radiolableled VirG

Question 62

Small non-coding RNA (sRNA)always inhibit translation initiation.

Question 63

Based on current research,quorum sensing has only been shown to occur in bioluminescent bacteria.

Question 64

Negative control of gene regulation involves the binding of a repressor molecule to the promoter to block transcription.

Question 65

The type of regulation that relies on a critical cell density is called ______ sensing

Question 66

The phenotype of a lacI mutant that has the lacI gene partially deleted is constitutive expression of β-galactosidase.

Question 67

RNA transcriptional control that is achieved through mRNA secondary structure modification relies upon: (Select all that apply)

A)competition between different regions able to form stem-loop structures
B)abundance of key codons within leader sequences upstram of operon genes
C)single stranded RNA's ability to form hairpin structures
D)Shine Dalgarno sequence sequestration
E)None is a correct choice

Question 68

The transfer of T-DNA into a plant cell by Agrobacterium tumefaciens is regulated by: (Select all that apply)

A)virA phosphorylation of virG
B)virG phosphorylation of virA
C)VirA phosphorylation of VirG
D)VirG phosphorylation of VirA
E)ATP-mediated phosphorylation of VirA

Question 69

Chemotaxis is a time-based or temporal response to a chemical gradient.

Question 70

Diauxic growth reflects the preferential utilization of one carbon source over another carbon source.

Question 71

The regulated movement of a microbe towards or away from a chemical is called __________.