Exam 2 Chapter 14

What happens when levels of allolactose rise inside an E. coli cell?

Allolactose binds to the lac repressor and prevents it from binding to the operator.

The enzyme β-galactosidase is encoded by which gene? Multiple choice question. LacO LacY LacA LacZ

LacZ

The enzyme β-galactosidase is encoded by which gene? Multiple choice question. LacZ LacY LacO LacA

LacZ

What is the name for a strain of bacteria containing an F' factor? Multiple choice question. Diploid Heterodimer Mutant Merozygote

Merozygote

The enzyme beta-galactosidase cleaves the sugar lactose into ....... and ........

Blank 1: glucose Blank 2: galactose

When four molecules of allolactose are bound to lac repressor, and repressor can no longer bind to operator, and RNA polymerase is free to transcribe the operon, the operon has been .......

induced

As levels of allolactose increase within an E. coli cell, allolactose binds to the lac ...... , promoting a conformational change that prevents binding to the ....... site on the DNA.

Blank 1: repressor Blank 2: operator

True or false: Effector molecules influence gene expression by binding to DNA. True false question. True False

False

True or false: The lac repressor does not completely inhibit transcription of the lacZ, lacY, and lacA genes. True false question. True False

True

Constitutive genes ______. Multiple choice question. are unregulated. respond to lactose levels in the cell. are regulated by glucose levels. respond to amino acid levels in the cell.

are unregulated.

Constitutive genes ______. Multiple choice question. respond to lactose levels in the cell. respond to amino acid levels in the cell. are unregulated. are regulated by glucose levels.

are unregulated.

When four molecules of allolactose are bound to the lac repressor, the lac operon is induced, and RNA polymerase ______. Multiple choice question. binds to operator is blocked from transcribing any genes transcribes the operon transcribes more slowly

transcribes the operon

How does an effector molecule influence gene expression?

The effector molecule binds to a regulatory protein and affects its ability to bind DNA.

An operon is a group of two or more genes under the transcriptional control of ______.

a single promoter

A regulatory protein that increases the rate of transcription is a(n) .......

activator

Constitutive genes encode proteins the cell needs ______. Multiple choice question. occasionally when certain nutrients are in the environment all the time to make amino acids

all the time

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

allolactose

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

allolactose

The Lac repressor protein binds to the operator and ______. Multiple choice question. stops transport of lactose blocks transcription prevents translation aids RNA polymerase

blocks transcription

When the lac repressor is bound to the operator, RNA polymerase ______ the lacZ, lacY, or lacA genes. Multiple choice question. increases transcription of cannot transcribe transcribes one of

cannot transcribe

When lactose is depleted from the environment, the ______.

intracellular concentration of allolactose falls

The ______ gene encodes a repressor protein. Multiple choice question. lacO lacI lacZ lacP lacA

lacI

A protein such as a repressor that inhibits transcription is exerting ....... control of transcription.

negative

A polycistronic mRNA contains the sequence(s) ______. Multiple choice question. of two or more genes for genes from different operons for only one gene for several genes and control regions

of two or more genes

When the lac repressor binds to the lac ..... site, RNA polymerase cannot transcribe the lacZ, lacY or lacA genes

operator

Transcription regulation by an activator protein is considered to be ______ control. Multiple choice question. positive negative

positive

Allolactose is a small effector molecule that binds to the lac repressor and ______. Multiple choice question. prevents repressor from binding to DNA prevents repressor from binding to RNA polymerase increases the affinity of repressor for CAP facilitates repressor binding to DNA

prevents repressor from binding to DNA

In bacteria, the most common way to regulate gene expression is by influencing ______. Multiple choice question. the rate of translation initiation the rate of transcription initiation the frequency of cell division the rate of transcription elongation

the rate of transcription initiation

The product of the lacY gene is required for ______. Multiple choice question. the transport of lactose into the bacterial cell cleaving lactose into glucose and galactose converting a small amount of lactose into allolactose covalently modifying lactose and lactose analogs

the transport of lactose into the bacterial cell

The research of Jacob and Monod provided ______. Multiple choice question. our initial understanding of how transformation occurs our initial understanding of gene regulation understanding of the process of translation understanding of the process of DNA replication the details pertaining to the structure of DNA

our initial understanding of gene regulation

The lacY gene encodes lactose ....... , a membrane protein.

permease

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

polycistronic

In an operon, the ______ signals the beginning of transcription. Multiple choice question. origin terminator promoter ribosome binding site

promoter

The phenomenon in which the level of gene expression can vary under different conditions is gene .....,..

regulation

A regulatory protein that binds to DNA and inhibits transcription is a(n) ......

repressor

A regulatory protein that binds to DNA and inhibits transcription is a(n) .......

repressor

The intracellular concentration of the inducer ...... remains high as long as lactose is available in the environment.

allolactose

Unregulated genes are also called ....... genes.

constitutive

The research of Monod and Jacob that led to the initial understanding of gene regulation stemmed from an interest in ______.

enzyme adaptation

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

operon

The three protein-encoding genes in the lac operon are ....... ....... .......

Blank 1: lacZ Blank 2: lacY Blank 3: lacA

True or false: Gene expression is always the same. True false question.TrueFalse

False

True or false: Gene regulation is constant. True false question.TrueFalse

False

The research of Monod and Jacob that led to the initial understanding of gene regulation stemmed from an interest in ______. Multiple choice question. enzyme adaptation the amino acid tryptophan the sugar lactose

enzyme adaptation

The research of Jacob and Monod provided ______.

our initial understanding of gene regulation

The operon is flanked by a ....... that signals the beginning of transcription and a ....... that signals the end of transcription.

Blank 1: promoter Blank 2: terminator

The three protein-encoding genes in the lac operon are ...... ...... ......

Blank 1: lacZ Blank 2: lacY Blank 3: lacA

True or false: The rate of transcription initiation rarely influences overall gene expression. True false question.TrueFalse

False

What type of genes encode proteins the bacterial cell needs all the time? Multiple choice question. Repressor genes Constitutive genes Activator genes Riboswitches

Constitutive genes

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

allolactose

When bound to operator, the lac repressor ______.

allows very small amounts of the lac enzymes to be made

Unregulated genes have ______ Multiple choice question. constant levels of expression. variable levels of expression. constant or variable levels of expression depending on the gene.

constant levels of expression.

Unregulated genes have ______ Multiple choice question. constant or variable levels of expression depending on the gene. constant levels of expression. variable levels of expression.

constant levels of expression.

The binding of ______ to the lac repressor promotes a conformational change that prevents the repressor from binding to the lac operator. Multiple choice question. allolactose β-galactosidase lactose Lac permease

allolactose

Select all of the following that are protein-encoding genes in the lac operon. Multiple select question. lacY lacA lacZ lacO lacX

lacY lacA lacZ