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