Microbiology Chapter 14

At which of the following operator sites must the lac repressor bind to ensure transcription inhibition? Multiple choice question. 01 O4 O2 O3

01

At which of the following operator sites must the lac repressor bind to ensure transcription inhibition? Multiple choice question. O4 01 O2 O3

01

When lactose catabolism is not required, the lac repressor binds to one of ___________ different lac operators.

3

When lactose catabolism is not required, the lac repressor binds to one of _____________ different lac operators.

3

Which of the following is the inducer of the lac operon? Multiple choice question. Lactose Galactose Maltose Allolactose

Allolactose

Transcription of the trp operon is regulated at the level of initiation by the trp repressor, and at the level of elongation by a process called _________________.

Blank 1: attenuation

In E.coli regulatory pathways, which molecule functions to ensure that glucose is used as the preferred carbon and energy source? Multiple choice question. CPA CAP GDP ATP

CAP

Which two proteins are regulators of the lac operon? Multiple select question. RNA polymerase Catabolite activator protein lac repressor lac transcriptase Lactose permease

Catabolite activator protein lac repressor

Which of the following is NOT a component of bacterial operons? Multiple choice question. Enhancer Structural genes Operator Promoter

Enhancer

Which of the following is NOT a component of bacterial operons? Multiple choice question. Promoter Enhancer Operator Structural genes

Enhancer

Which of the following is NOT a component of bacterial operons? Multiple choice question. Structural genes Operator Enhancer Promoter

Enhancer

True or false: The trp operon is an example of a positive control system. True false question.TrueFalse

False

Which two of the following conditions must exist to fully induce the lac operon? Multiple select question. Lack of preferred carbon and energy source Shortage of tryptophan Excess of preferred carbon and energy source Lactose present in the medium Excess of tryptophan Glucose present in the medium

Lack of preferred carbon and energy source Lactose present in the medium

Which three of the following are components of a bacterial operon? Multiple select question. Inducer RNA polymerase Operator Repressor Promoter Structural genes

Operator Promoter Structural genes

Which statement about the trp operon is true? Multiple choice question. Operon is functional whether tryptophan is present or absent. Operon is functional when tryptophan is absent. Operon is repressed when tryptophan is absent.

Operon is functional when tryptophan is absent.

Which three of the following are components of a bacterial operon? Multiple select question. RNA polymerase Repressor Promoter Structural genes Operator Inducer

Promoter Structural genes Operator

In the regulation of the trp operon of E. coli, when translation does not occur, which of the following happens? Multiple choice question. The ribosome stalls while translating the leader peptide, and translation becomes uncoupled to transcription. Transcription stops before the RNA polymerase reaches the gene encoding the leader peptide. The antiterminator loop forms and transcription stops before RNA polymerase reaches the structural genes of the operon. The pause and terminator loops form and transcription stops before RNA polymerase reaches the structural genes of the operon.

The pause and terminator loops form and transcription stops before RNA polymerase reaches the structural genes of the operon.

The trpL operon encodes the leader peptide and ____________ sequences.

attenuator

The trpL operon encodes the leader peptide and ________________ sequences.

attenuator

The lac repressor protein inhibits transcription by ____. Multiple choice question. bending DNA in the promoter region digestion of polycistronic message blocking lactose transport into cell allosteric regulation of RNA polymerase

bending DNA in the promoter region

The lac repressor protein inhibits transcription by ____. Multiple choice question. digestion of polycistronic message blocking lactose transport into cell bending DNA in the promoter region allosteric regulation of RNA polymerase

bending DNA in the promoter region

DNA-bound repressor proteins inhibit the initiation of transcription by either ____. Multiple select question. blocking the binding of RNA polymerase removing RNA polymerase from promoter facilitating the binding of RNA polymerase preventing the movement of RNA polymerase

blocking the binding of RNA polymerase preventing the movement of RNA polymerase

The binding of _____________ to the catabolite activator protein causes it to change to the active form.

cAMP

The catabolite activator protein functions in a regulatory network that allows E. coli to preferentially use ____________________ over all other carbon and energy sources. Listen to the complete question

glucose

The level of some enzymes, such as β-galactosidase, increase significantly in the presence of a small effector molecule called a(n) ________________________ .

inducer

Small effector molecules whose presence increases the level of specific enzymes are called ____. Multiple choice question. inducers regulators cofactors repressors

inducers

_______________________ genes encode enzymes whose level is increased by the presence of small effector molecules.

inducible

Lactose is transported into the E. coli cell by ____. Multiple choice question. β-galactosidase lactose repressor lactose transacetylase lactose permease

lactose permease

The trpL operon encodes the ________ peptide and attenuator sequences.

leader

For most transcriptional riboswitches, there are two configurations of the mRNA leader region. The configuration is determined by effector binding to the _____. Multiple choice question. gene promoter mRNA leader RNA polymerase ribosome

mRNA leader

Bacterial repressor proteins bind to a DNA sequence called the ___________________ .

operator

In bacteria, repressor proteins bind to a specific DNA sequence called the ____. Multiple choice question. operator terminator enhancer promoter

operator

A(n) ____________ protein is a DNA-binding protein that inhibits transcription initiation.

repressor

When _____________ proteins bind to the operator they block the binding of RNA polymerase or inhibit its movement.

repressor

Proteins that inhibit transcription initiation by binding to DNA are called _____. Multiple choice question. repressor proteins binding proteins activator proteins termination proteins

repressor proteins

In the trp operon of E. coli, when charged tRNA-Trp is abundant in the cell, the terminator loop forms in the transcript because _____. Multiple choice question. the ribosome follows RNA polymerase and efficiently synthesizes the TrpL peptide RNA polymerase follows the ribosome and efficiently transcribes the trpL gene the UGA stop codon results in the formation of the antiterminator loop in the transcript

the ribosome follows RNA polymerase and efficiently synthesizes the TrpL peptide

As a general rule, Gram-negative bacteria use riboswitches to regulate the _____________ of mRNA, and Gram-positive bacteria use riboswitches to regulate ___________ termination.

translation, transcription

The nucleotide sequence that encodes the leader sequence of the trp operon is ____. Multiple choice question. trpL trpR trpA trpY

trpL

Which two of the following statements about the inhibition of transcription by the lac repressor protein are true? Multiple select question. Binds to the O2 and O3 lac operator sites Bends the DNA in the promoter region Binds and inhibits RNA polymerase Degrades the polycistronic message Binds to O1 and one additional lac operator site

Bends the DNA in the promoter region Binds to O1 and one additional lac operator site

Which two of the following statements about the interaction between the lac repressor and inducer are true? Multiple select question. Inducer binds covalently to the lac repressor. Inducer binding changes the repressor shape. Inducer binding recruits the repressor to the operator. Inducer binding causes repressor to lose ability to bind to the operator sites.

Inducer binding changes the repressor shape. Inducer binding causes repressor to lose ability to bind to the operator sites.

The sugar _____________________________ is the inducer of the lac operon.

allolactase

A regulatory process that results in transcription termination within a leader sequence that precedes the structural genes is termed _________________ . Listen to the complete question

attenuation

Termination of transcription elongation before RNA polymerase enters the first structural gene of an operon is called ____. Multiple choice question. polymeric repression reverse transcription attenuation alternative splicing

attenuation

Transcription initiation of the trp operon is regulated by both ____. Multiple select question. attenuation ara repressor alternation trp repressor trp activator

attenuation trp repressor

In E. coli, the proteins necessary to utilize lactose as an energy and carbon source will not be expressed, even when lactose is present, unless the __________ _____________ protein is activated by the absence of glucose in the cell.

catabolite activator

The lac operon is under the regulatory control of the lac repressor protein, and the ___________ _____________ protein or CAP.

catabolite activator

The global control of operons encoding enzymes for the catabolism of carbohydrates that must be modified prior to entering glycolysis is referred to as ____. Multiple choice question. competitive inhibition catabolite repression feedback inhibition carbohydrate repression

catabolite repression

______________ genes are continuously expressed.

constitutive

Genes that are continuously expressed

constitutive genes

gram positive bacteria

control of transcription

Regulation of transcription initiation for the trp operon is accomplished at two levels, 1: transcription initiation by the trp repressor and 2: transcription ___________________ by the process called attenuation.

elongation

DNA-bound activator proteins promote transcription initiation by ____. Multiple choice question. facilitating RNA polymerase binding preventing the movement of RNA polymerase blocking the binding of RNA polymerase removing RNA polymerase from promoter

facilitating RNA polymerase binding

True or false: The trp operon is an example of a positive control system. True false question. True False

false

The binding of inducer to the lac repressor protein does NOT result in which of the following? Multiple choice question. lac repressor is inactivated lac repressor binds to operator lac repressor changes shape

lac repressor binds to operator

The trp operon is best described as an example of the ______. Multiple choice question. negative transcriptional control of repressible genes negative transcriptional control of inducible genes positive transcriptional control of inducible genes positive transcriptional control of repressible genes

negative transcriptional control of repressible genes

Genes that are expressed only when the enzymes they encode are needed are said to be ____. Multiple choice question. structural repressible constitutive regulated

regulated

The nucleotide sequence that includes the attenuator sequences of the trp operon is ____. Multiple choice question. trpR trpY trpL trpA

trpL

In this image of the trp operon, the repressor protein is indicated by the letter R. What is the co-repressor molecule (circled) needed for the repressor protein to be able to bind to DNA? Multiple choice question. cAMP lactose tryptophan glucose

tryptophan

Lactose is converted to allolactose in the E. coli cell by ____. Multiple choice question. lactose transacetylase lactose repressor β-galactosidase lactose permease

β-galactosidase

A(n) _______________ protein is a DNA-binding protein that promotes transcription initiation.

activator

When ________________ proteins bind to their transcriptional regulatory sites they facilitate the binding of RNA polymerase.

activator

Question Mode Multiple Choice Question Proteins that promote transcription initiation by binding to DNA are called ____. Multiple choice question. repair proteins binding proteins repressor proteins activator proteins

activator proteins

The enzyme β-galactosidase converts lactose to ___________________. Listen to the complete question

allolactose

Binding of an effector to one domain of a transcriptional regulatory protein changes the conformation of its DNA-binding domain. This is an example of _____. Multiple choice question. quorum sensing allosteric control transcriptional control catabolite control

allosteric control

Genes that are expressed continuously are called ____. Multiple choice question. developmental genes homeobox genes constitutive genes regulatory genes inducible genes

constitutive genes

gram negative bacteria

control of translation

Aporepressors are activated by the binding of a(n) ____. Multiple choice question. promoter operator inducer corepressor

corepressor

Question Mode Fill in the Blank Question Fill in the blanks to complete the sentence. Aporepressors are synthesized in an inactive form and are activated by the binding of small effector molecules called _____________.

corepressor

In this image of the trp operon, the repressor protein, indicated by the letter R, binds to the DNA at the _____ site. Multiple choice question. promoter Shine-Dalgarno terminator operator

operator

In the trp operon of E. coli, when there is little charged tRNA-Trp present in the cell, the antiterminator loop forms in the transcript because _____. Multiple choice question. there is no ribosome accompanying the RNA polymerase as it transcribes the trpL gene the RNA polymerase and the ribosome are both moving at maximal speeds the Shine-Dalgarno sequence of the trpL gene is sequestered in the terminator loop the ribosome stalls but the RNA polymerase keeps moving along the transcript

the ribosome stalls but the RNA polymerase keeps moving along the transcript

_____________ genes encode enzymes that have their expression levels decreased by the presence of pathway products.

Repressible

______________ genes encode enzymes that have their expression levels decreased by the presence of pathway products.

Repressible

________________ genes encode enzymes that have their expression levels decreased by the presence of pathway products.

Repressible

Which two of the following are mechanisms that can control transcription of the trp operon by way of the attenuator region? Multiple select question. Ribosome stalls in region 1 due to low tryptophan levels - antiterminator loop forms Ribosome translates at normal speed due to adequate tryptophan levels - antiterminator loop forms Ribosome stalls in region 1 due to low tryptophan levels - terminator loop forms Ribosome translates at normal rate due to adequate tryptophan levels - pause and terminator loops are formed

Ribosome stalls in region 1 due to low tryptophan levels - antiterminator loop forms Ribosome translates at normal rate due to adequate tryptophan levels - pause and terminator loops are formed

Which two of the following statements about the interaction between the lac repressor and inducer are true? Multiple select question. Inducer binds covalently to the lac repressor. Inducer binding changes the repressor shape. Inducer binding causes repressor to lose ability to bind to the operator sites. Inducer binding recruits the repressor to the operator.

Inducer binding changes the repressor shape. Inducer binding causes repressor to lose ability to bind to the operator sites.

Which condition is most likely to NOT result in attenuation of transcription of the trp operon? Multiple choice question. Slow ribosome activity due to low tryptophan levels Normal ribosome activity due to adequate tryptophan levels No ribosome activity on trp mRNA

Slow ribosome activity due to low tryptophan levels

For most transcriptional riboswitches, there are two configurations of the leader of an mRNA. What determines the configuration of the leader region? Multiple choice question. where RNA polymerase initiates transcription effector binding to the Shine-Dalgarno sequence cellular concentration of ribonucleotides effector binding to the mRNA

effector binding to the mRNA

When ____________ is present in the environment, it is transported into E. coli cells by lactose permease.

lactose

Order the following events in the regulation of the trp operon of E. coli when charged tRNA-Trp is abundant in the cell.

RNA polymerase initiates transcription at the promoter a ribosome initiates translation of the trpL gene the trpL peptide is synthesized effeciently the terminator loop forms in the transcript RNA polymerase falls off the template translation terminates at the UGA stop codon

In the context of transcriptional regulatory proteins, allosteric control refers to _____. Multiple choice question. an effector binding in one domain changing the conformation of another domain the need for corepressors in proteins that regulate biosynthetic pathways the conversion of lactose to allolactose to induce the lac operon binding of an amino acid to the DNA binding domain of its repressor protein

an effector binding in one domain changing the conformation of another domain

Which two proteins are regulators of the lac operon? Multiple select question. lac repressor Lactose permease Catabolite activator protein lac transcriptase RNA polymerase

lac repressor Catabolite activator protein

The binding of inducer to the lac repressor protein does NOT result in which of the following? Multiple choice question. lac repressor changes shape lac repressor binds to operator lac repressor is inactivated

lac repressor binds to operator

In this image of the lac operon, the structural genes are _____. Multiple choice question. lacI and lacY lacZ and lacY lacI, lacZ, lacY, and lacA lacZ, lacY, and lacA

lacZ, lacY, and lacA

The lac operon is expressed at high levels when the sugar ________________ is available and a preferred source of carbon and energy is lacking.

lactase

The trp operon is best described as an example of the ______. Multiple choice question. positive transcriptional control of inducible genes positive transcriptional control of repressible genes negative transcriptional control of repressible genes negative transcriptional control of inducible genes

negative transcriptional control of repressible genes

Proteins that are responsible for the induction or repression of enzyme encoding genes are referred to as ____________ proteins.

regulatory

Proteins involved in the control of gene expression in processes such as induction and repression are referred to as ____. Multiple choice question. developmental proteins regulatory proteins structural proteins transport proteins

regulatory proteins

The genes that encode enzymes that have their expression levels decrease in the presence of pathway end-products are best described as ____. Multiple choice question. constitutive genes repressible genes housekeeping genes inducible genes

repressible genes

Which of the following is the inducer of the lac operon? Multiple choice question. Maltose Allolactose Lactose Galactose

Allolactose

Which two of the following statements about the interaction between the lac repressor and inducer are true? Multiple select question. Inducer binding recruits the repressor to the operator. Inducer binding causes repressor to lose ability to bind to the operator sites. Inducer binds covalently to the lac repressor. Inducer binding changes the repressor shape.

Inducer binding causes repressor to lose ability to bind to the operator sites. Inducer binding changes the repressor shape.

The genes that encode enzymes that have their expression levels decrease in the presence of pathway end-products are best described as ____. Multiple choice question. inducible genes constitutive genes repressible genes housekeeping genes

repressible genes

The genes that encode enzymes that have their expression levels decrease in the presence of pathway end-products are best described as ____. Multiple choice question. repressible genes inducible genes constitutive genes housekeeping genes

repressible genes

In the regulation of the trp operon of E. coli, when translation does not occur, the pause and terminator loops form and transcription stops before ____ reaches the structural genes of the operon. Multiple choice question. RNA polymerase the leader peptide the ribosome

RNA polymerase

Order the following events in the regulation of the trp operon of E. coli when there is little charged tRNA-Trp present in the cell.

RNA polymerase initiates transcription at the promoter a ribosome initiates translation of the trpL gene the ribosome stalls, in need of charged tRNA-trp an antiterminator loop forms in the transcript RNA polymerase transcribes the structural genes of the trp operon the antiterminator loop forms in the transcript

genes that are only expressed when needed

regulated genes

Which two of the following statements about the inhibition of transcription by the lac repressor protein are true? Multiple select question. Binds to the O2 and O3 lac operator sites Bends the DNA in the promoter region Binds to O1 and one additional lac operator site Binds and inhibits RNA polymerase Degrades the polycistronic message

Bends the DNA in the promoter region Binds to O1 and one additional lac operator site

Transcription of the trp operon is controlled by which two of the following mechanisms? Multiple select question. Repressor protein inhibits initiation Premature termination through attenuation Activator protein enables initiation Repression of termination by the ribosome

Repressor protein inhibits initiation Premature termination through attenuation

Enzymes whose level increases in the presence of small effector molecules are encoded by ____. Multiple choice question. regulatory genes housekeeping genes inducible genes constitutive genes repressible genes

inducible genes

The trp operon is best described as an example of the ______. Multiple choice question. negative transcriptional control of inducible genes positive transcriptional control of inducible genes positive transcriptional control of repressible genes negative transcriptional control of repressible genes

negative transcriptional control of repressible genes