Genetics Chapter 15 Practice Qs (Midterm 3)

Mechanisms of quorum sensing in Vibrio fischeri. 1). Luxl synthesizes and releases autoinducer 2). Autoinducer enters the ell 3). autoinducer reaches a threshold 4). Autoinducer binds LuxR 5). Biolominescence operon is transcribed

1). Luxl synthesizes and releases autoinducer 2). Autoinducer enters the ell 3). autoinducer reaches a threshold 4). Autoinducer binds LuxR 5). Biolominescence operon is transcribed

Prokaryotes regulate gene expression by activating, inhibiting, increasing, or decreasing the blank1 of specific genes, and/or interfering with the blank2 of the mRNAs of those genes.

1). Transcription 2). Translation

Because it was easy to measure the levels of blank-1, the lacZ gene which encodes this enzyme can be used as a(n) blank-2 gene to detect the amount of transcription that occurs in response to any specific regulatory element.

1). beta-galactosidase 2). reporter

How many lac operator sites are there?

3

The ribosome-binding site is a special initiation site located at the

5' end of the open reading frame

The lac operon genes are transcribed together in what order?

5'lacZ-lacY-lacA-3'

The transport of glucose into a bacterial cell causes the intracellular level of cAMP to fall because the enzyme blank blank is inhibited

Adenylyl cyclase

The binding of the blank, to the repressor causes an allosteric effects that abolishes the repressor's ability to bind to the operator

Allolactose

How does an effector molecule influence gene expression?

Effector molecule binds to a regulatory protein and affects its ability to bind DNA

the phenomenon in which the level of gene expression in prokaryotes can vary under different conditions is termed prokaryotic blank blank

Gene Regulation

The synthesis of RNAs and proteins according to the instructions encoded in dNA is a process called. -Gene transformation, regulation, expression, or induction.

Gene expression

The E. coli complete RNA polymerase blank consist of the core enzyme plus the sigma factor. -alloenzyme, autoenzyme, haloenzyme, heteroenzyme, and homoenzyme.

Haloenzyme

A catabolic pathway is turned on only in the presence of the molecules to be broken down. This is termed bank regulation.

Inducible

The lacA gene encodes a transacetylase, enzyme that covalently modifies -the promoter, RNA polymerase, lactose, beta-galactosidase, or lactose permease.

Lactose

When the tryptophan level in the cell is high/low, the ribosome pauses in region one of the trpL mRNA, causing region 2 to bind to region 3 and transcription to continue.

Low

Which of the following are regulatory DNA elements of the lac operon? -operator, activator, promoter, repressor, inducer.

Operator and Promoter

A(n) blank is a group of two or more genes under transcriptional control of a single promoter.

Operon

To initiate translation, ribosomes attach to the mRNA at a site called the what site?

Ribosome-binding

Blank are allosteric RNA leaders that bind small effector molecules to control gene expression. -Attenuators, Riboswitches, Antiterminators, and Regulons.

Riboswitches

In attenuation, the level of an amino acid governs the conformation of the leader indirectly. However, leaders that act as blank, change conformation by binding a particular effector directly

Riboswitches

the lac operon is produced by the block located where? Which element does it bind to?

Right in front. The one right before the frame. Or skip one.

In bacteria, the most common way to regulate gene expression is by influencing?

The rate of transcription initiation

A protein that can diffuse through the cytoplasm and act at DNA target sites elsewhere in the genome is called a blank-acting element.

Trans

The base sequence of the RNAs that a cell produces under a particular set of conditions Is known as the

Transcriptome

In attenutation, transcription a). is stopped prematurely b). proceeds half-way through the operon c). never starts d). continues to the transcription site

a). Is stopped prematurely

Which of the following mechanisms are possible for anitsense RNAs? a). inhibition of mRNA transcription b). degradation of mRNA c). activation of mRNA translation d). inhibition of mRNA translation

a). inhibition of mRNA transcription b). degradation of mRNA d). inhibition of mRNA translation

The product of the lacA gene adds blank groups to the lactose and other sugars

acetyl

The transport of glucose into a bacterial cell causes the intracellular level oc cyclic-AMp to fall because the enzyme blank blank is inhibited.

adenylyl cyclase

Antisense RNA is an RNA strand that is blank to an mRNA molecule

complementary

The small nucleotide blank blank blank (cAMP) binds to a protein called CRP, and the complex can positively regulate the lac operon.

cyclic adenosine monophosphate

A polycistronic mRNA a). contains the sequence for only one gene b). contins the sequences for several genes and control regions c). contains the sequences for genes from different operons d). contains the sequences of two or more genes

d). contains the sequences of two or more genes

During the initiation step of transcription, DNA is unwound by the action of the enzyme. a). RNase b). DNA helicase c). DNase e). RNA polymerase

e). RNA polymerase

cAMP is a(n) a). effector molecule that helps in the negative control of the lac operon b). Source of energy used in transport of lactose c). effector molecule that helps in the positive control of the lac operon d). source of energy used in the breakdown of lactose

effector molecule that helps in the positive control of the lac operon

The process by which a specific molecule stimulates synthesis of a given protein is called

induction

The blank gene encodes a repressor protein lac...Z, A, P, O, or I(capital i)

lacI Lac+capital i

Select all of the following that are protein-encoding genes in the lac operon. -lac O, Y, X, A, and Z

lacY, lacA, lacZ

Which Vibrio fischeri genes encode the quorum-sensing proteins? lux R, B, I(capital i), A, or C

luxR and luxI

When the lac repressor binds the blank, RNA polymerase cannot transcribe the lacZ, lacY, and lacA genes (yaz).

operator

In the lac operon, some of the nucleotides of the operator are also part of the -promoter, terminator, activator, repressor, or inducer.

promotor

An RNA molecule that can exist in two different secondary conformations and thereby affect gene regulation is known as a(n)

riboswitch

Select the genes in the trip operon

trp...BCADE

The small effector molecule blank prevents the lac repressor from binding to operator.

Allolactose

Regulatory RNAs that are transcribed from the opposite DNA strand to that of the mRNA are called blank RNAs

Antisense

The trp operon is regulated by a repressor protein and by blank I which transcription is stopped prematurely.

Attenuation

Transcription begins but terminated before the entire mRNA is made during

Attenuation

Which two mechanisms control expression of the trp operon in E. coli? -Induction, transformation, attenuation, and repression.

Attenuation, and Repression.

An effector is a small molecule that binds to what an then?

Binds to a protein and changes its conformation

An operon encodes a blank mRNA, an RNA that contains the sequences of two or more genes.

Polycistronic

Transcription in prokaryotes begins when the RNA pol holoenzyme binds to specific DNA sequences in a region called blank

Promoter

In the lac operon, the two main regulatory DNA elements are the blank and the blank.

Promoter, and Operator

Which of the following proteins may function as a dimer or tetramer? a). Beta-galactosidase b). transacetylase c. lac repressor d). lac permease

c).Lac repressor

The positive regulator of the lac operon is the blank blank protein (CRP)

cAMP Receptor

Match the gene of the lac peron to its correct product a). lacZ b). lacY c). lacA d). Beta-galactosidase e). Transacetylase f). Lac permease

a). lacZ-Beta-galactosidase b). lacY-Lac permease c). lacA-transacetylase

Constitutive mutants a). synthesize certain proteins all the time b). lac the ability to synthesize proteins c). synthesize certain proteins occasionally d). synthesize only one category of proteins

a). synthesize certain proteins all the Tim

The entire set of RNAs produced by a cell is called its a). transcriptome b). microbiome c). proteome d). genome

a). transcriptome

In the trip operon, tryptophan acts as a a). an activator b). a core repressor c). a lone repressor d). an enzyme

b). Core repressor

The conversion of a riboswitch from one conformation to another is due to a). the presence of a CAP b). the covalent modification of the final product c). the binding of a small molecule d). a corerepressor

b). The binding of a small nucleotide

Which of the following statements about antisense RNAs are true? a). The have no promoters b). The can be complementary to the entire mRNA c). They can be complementary to only part of the mRNA d). They range in size from 1000-5000 nucleotides

b). The can be complementary to the entire mRNA c). They can be complementary to only part of the mRNA

The genes in the trp operon encode a). enzymes used to metabolize tryptophan in the environment, the proteins encoded by the top operon are used to produce the amino acid tryptophan b). only the subunits of the trp repressor protein c). enzymes used in tryptophan biosynthesis d). regulatory proteins only

c). enzymes used in tryptophan biosynthesis

An inducer is a small effectormolecule that causes transcription to a). remain constant b). decrease c). increase

c). increase

Blank is a bacterial communication system that allows them to adjust their behavior according to their population density. a). signal transduction b). catabolite repression c). quorum sensing d). Autonomous specification e). chemotactic signaling

c). quorum sensing

Allolactose is a blank of the lac operon a). a DNA region b). a product c). the inducer d). the repressor

c). the inducer

Small RNA (sRNA) molecules regulate a). transcription in trans by base-pairing with DNA b). transcription in cis by base-pairing with DNA c). translation in trans by base-pairing with mRNAs d). translation in cis by base-pairing with mRNAs

c). translation in trans by base-pairing with mRNAs

Pathways that break down complex molecules into smaller units are termed blank, while pathways that construct end product molecules from simpler units are called blank?

Catabolic, Anabolic

Inducible operons usually encode blank enzymes, and repressible operons usually encode blank enzymes. -Catabolic; anabolic -Anabolic; catabolic

Catabolic; anabolic

The enzyme that transcribes a gene's DNA into RNA is called?

RNA polymerase

This figure highlights the use of lacZ as a(n) (you need the picture) But it is right before the "STOP"

Reporter Gene

A pathway that is turned off when the cell has enough of the end product is under what type of regulation?

Repressible

The normal house keeping sigma factor is

Sigma 70

In prokaryotes, the RNA polymerase holoenzyme is composed of the core enzyme plus the blank blank

Sigma factor

The core repressor for a repressible operon may be a). the product of that operon b). the substrate of the first enzyme encoded by the operon. Often the end produce of a pathway is a regulatory molecule. c). a large sugar molecule d). the product of a gene that is not part of the operon.

a). the product of that operon

A conformational change that prevents repressor from binding to the lac operator occurs when blank binds to the lac repressor.

allolactose

How does tryptophan function in the regulation of the trp operon? a). it binds to the repressor preventing it from binding to DNA thus allowing transcription of the operon b). it bind to the repressor and only then can this complex bind to DNA thus preventing transcription of the operon c). It binds directly to DNA and inhibits its transcription of the operon d). It binds to the repressor and only then can the repressor bind to DNA allowing transcription of the operon.

b). it bind to the repressor and only then can this complex bind to DNA thus preventing transcription of the operon

Why does transcription of the top operon continue when tryptophan levels are low? a). the ribosome pauses in region 2, causing the 3-4 stem-loop to form b). the ribosome continues through the trpL mRNA, preventing the 3-4 stem-loop from forming c). The ribosome pauses in region 1, preventing the 3-4 stem-loop from forming d). the ribosome continues through the trpL mRNA, causing the 3-4 stem-loop to form

c). The ribosome pauses in region 1, preventing the 3-4 stem-loop from forming

When the lac repressor is bound to the operator, RNA polymerase blank the lacZ, lacY, or lacA genes. a). transcribes one of b). increases transcription of c). cannot transcribe

c). cannot transcribe

The product of an operon may act as a(n) blank if the operon is repressible.

Corerepressor

The somewhat imprecise term that describes how transcriptional regulation is influenced by glucose is blank blank?

Catabolite Repression

A DNA segment that must be adjacent to the gene(s) it regulates is called a blank-acting element.

Cis

A(n) blank mutant is an organism that synthesizes certain proteins all the time, regardless of environmental conditions.

Constitutive

Mutants whose genes are unregulated are called blank mutants

Constitutive

A small effector molecule that binds to a repressor protein and allows it to bind to DNA is called a(n)

Corepressor

A core repressor is a a). a protein that binds to DNA and help recruit the repressor b). small effector molecule that binds to DNA and blocks the repressor protein from biding c). small effector molecule that binds to a repressor protein and releases it from DNA d). small effector molecule that binds to a repressor protein and allows it to bind to DNA e). a protein that can substitute for a mutated repressor protein.

d). small effector molecule that binds to a repressor protein and allows it to bind to DNA

The lac operon structural genes are transcribed as a). three monocistronic mRNAs each with its own ribosome binding site b). three monocistronic mRNAs but only two of them have ribosome binding sites. c). part of a single polycistronic mRNA with only one ribosome binding site d). part of a single polycistronic mRNA with three independent ribosome binding sites

d). part of a single polycistronic mRNA with three independent ribosome binding sites

The lac repressor protein binds to the operator and a). prevents translation b). blocks transcription c). aids RNA polymerase d). stops transport of lactose

b). blocks transcription

Allolactose is a small effector molecule that binds to the lac repressor a). prevents repressor form binding to DNA b). increases the affinity of repressor for CAP c). facilitates repressor binding to DNA d). prevents repressor from binding to RNA polymerase

b). increases the affinity of repressor for CAP