Micro chapter 11

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.

a) A two-component system.

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.

a) Histidine kinase and a response regulator.

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.

a) It results in diauxic growth.

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

a) a homoserine lactone derivative

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.

a) activator protein

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.

b) By preferentially utilizing glucose first.

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.

b) It inactivates the LacI repressor protein.

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.

b) constant tumbling.

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.

b) global regulation.

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.

b) unregulated.

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.

c) Bind to a transcriptional activator protein to activate transcription of the lux genes.

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.

c) By a series of signal transduction events.

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.

c) By chemical signaling.

What would characterize the phenotype of a CheY 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.

c) Smooth swimming.

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.

c) When the repressor protein binds to the operator region.

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

c) cyclic-AMP

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

c) histidine kinase

The expression of genes required for biofilm formation occurs only after a cell has attached to a surface that is suitable for biofilm development. What is this type of gene expression called? a) attenuation b) feedback inhibition c) induction d) repression e) inhibition

c) induction

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

c) regulon

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.

c) transcription and translation occurring simultaneously.

The catabolite activator protein (CAP) enhances transcription of the lac operon by binding to an activator binding site upstream of the lac promoter. To become active, CAP must bind the co-activator ___________.

cAMP

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

chemotaxis

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.

d) A small molecule that binds to an enzyme to regulate its activity.

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.

d) Both repression and activation mechanisms.

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.

d) Identify the promoter region of a gene.

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.

d) It would repress β-galactosidase when lactose is present.

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.

d) The fusion of a promoter region of interest to a gene whose product can easily be measured.

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.

d) To sense the presence of a specific chemical.

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

d) corepressor or inducer

Small non-coding RNA molecules (sRNA) affect gene expression at the level of: a) transcription initiation. b) transcription termination. c) protein activity. d) translation. e) transcription activation.

d) translation.

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.

e) In either the lacI gene or operator region.

True/False: An effector molecule always inactivates an allosteric enzyme.

false

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

false

True/False: During chemotaxis, bacteria are able to determine if they are moving in the correct direction by measuring external chemical concentration at different points around the cell.

false

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

false

True/False: Small non-coding RNA (sRNA) always inhibit translation initiation.

false

True/False: The enzyme β-galactosidase hydrolyzes lactose to glucose and fructose.

false

The two-component regulatory systems uses a _______ ________ and a response regulator.

histidine kinase

Repressor proteins bind to the control region of a gene called the ___________.

operator

The directed movement toward a light source is called ______________.

phototaxis

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

quorum sensing.

RNA polymerase uses different ______ ________ for the global regulation of large blocks of genes.

sigma factors

True/False: An activator protein enhances transcription by binding to the DNA molecule upstream of the promoter to enhance the binding of the RNA polymerase to the promoter.

true

True/False: Chemotaxis is a time-based or temporal response to a chemical gradient.

true

True/False: Diauxic growth is the preferential utilization of one carbon source over another carbon source.

true

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

true

True/False: The two component regulatory system typically consists of a histidine kinase and a response regulator.

true