BIO 326 Exam 3 - Questions

promoter binding site

RNA polymerase

a regulatory protein that binds to DNA and increases the rate of transcription is an

activator

cyclic-AMP is a small effector molecule produced by the enzyme

adenylyl cyclase

constitutive genes encode proteins that the cell needs

all the time

a conformational change that prevents the repressor from binding to the lac operator occurs when ___ binds to the lac repressor

allolactose

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

allolactose

the small effector molecule that prevents the lac repressor from binding to the operator site is

allolactose

in the absence of lactose, the lac repressor

allows very small amounts of lac operon enzymes to be made

in the chi operon in B. subtitles, when levels of TPP are low, the 5' end of the mRNA forms a stem-loop structure called an ___ that allows transcription to continue

antiterminator

constitutive genes

are unregulated

the trp operon is regulated by a repressor protein and by ___ in which transcription is stopped prematurely

attentuation

a regulatory element that functions in the forward or reverse direction is said to be

bidirectional

the mRNA made from the trpL gene has four regions that can

bind repressor protein

an effector molecule exerts its effects by

binding to a repressor or activator

the lac repressor protein binds to the operator and

blocks transcription

when the lac repressor is bound to the operator, rna polymerase ___ the lacZ, lacY, or lacA genes

cannot transcribe

CAP site binding site

catabolite activator protein

term for how transcriptional regulation is influenced by glucose

catabolite repression

processes that are regulated at the genetic level

cell division response to the environment metabolism

a dna segment that must be adjacent to the gene it regulates is a

cis acting element

which are the functions of the enzyme B-galactosidase?

cleaves lactose into glucose and galactose coverts lactose into allolactose

transcription may be difficult or impossible if chromatin is in a

closed conformation

a protein that increases the rate of transcription but does not directly bind to the DNA is called a

coactivator

the phenomenon in which the combination of many factors determines the expression of a given gene is known as

combinatorial control

antisense RNA is an RNA strand that is ___ to an mRNA molecule

complementary

if a strain of E. coli has a mutation in the lacl gene such that the operon is expressed even in the absence of lactose, the expression is called ___

constitutive

post translational regulation refers to

control of proteins already in the cell

the binding of the lac repressor to the operator shuts down transcription from the lac operon when lactose is ___ the environment

depleted from

the sequential use of sugars by a bacterial cell is called

diauxic growth

the normal lacl gene on the f' factor could rescue the lacl mutants because the product of the lacl gene encodes a

diffusible protein

a glucocorticoid response element functions as an

enhancer

the binding of a regulatory transcription factor to an ___ can stimulate transcription 10- to 1000- fold, which is called ___ regulation

enhancer; up

activators bind to

enhancers

the genes in the trp operon encode ___

enzymes used in tryptophan biosynthesis

Monod, Jacob, and padre learned about the lac operon using bacterial strains called merozygotes. since lacl encodes a diffusible protein, in a merozygote, the gene on the ___ could supply the mutant cell with functional repressor protein.

f' factor

the transport of ___ into a cell causes a ___ in the concentration of cAMP by inhibiting adenylyl cyclase

glucose; decrease

when both lactose and glucose are absent from bacterial cells, concentrations of cAMP are

high

when tryptophan levels in the cell are ___, translation of the trpL mRNA continues to its stop codon, which terminates further transcription of the operon

high

in the trpL sequence, the 3-4 stem loop together with the U-rich attenuator sequence acts as an

intrinsic terminator

the ___ gene encodes a repressor protein

lacL

the enzyme B-galactosidase is encoded by which gene?

lacZ

the three protein-encoding genes in the lac operon are

lacZ lacY lacA

when only ___ is present in bacterial cells, cAMP levels are high

lactose

lacY gene encodes

lactose permeate---a membrane protein

when tryptophan levels in the cell are ___, the ribosome pauses in the trpL mRNA, allowing transcription of the rest of the operon

low

when tryptophan levels in the cell are ___, the trp repressor cannot bind to the ___ site. this allows RNA polymerase to transcribe the genes required for the synthesis of ___

low; operator; tryptophan

a repressor may stop ___ from allowing RNA polymerase to proceed to the ___ phase of transcription

mediator; elongation

a strain of bacteria containing f' factor genes is called a ___ or partial diploid

merozygote

plants and animals require a greater level of gene regulation that single-celled eukaryotes because of

mutlicellularity developmental stages more complex cell structure different tissue types

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

negative

a loss-of-function mutation in a gene encoding a repressor protein has the same effect as a mutation in the

operator site

a group of two or more genes under the transcriptional control of a single promoter is called an

operon

activator proteins stimulate mediator to regulate which modification of rna polymerase II?

phosphorylation

a repressor interacting with mediator prevents

phosphorylation of RNA polymerase

an operon encodes a ___ mRNA, an RNA that contains the sequence of two or more genes

polycistronic

control of proteins already present in the cell is called

posttranslational regulation

if gene regulation acts to prevent translation, which molecule will not be produced?

protein

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

rate of transcription initiation

DNA sequences in eukaryotes that can be bound by regulatory transcription factors, which then affect the ability of RNA polymerase to transcribe a particular gene are called ___

regulatory elements regulatory sequences control elements

DNA sequences that are analogous to the operator sites found near bacterial promoters are called ___ elements

regulatory or control

a regulatory protein that binds to DNA and inhibits transcription is called a

repressor

operator binding site

repressor

an inducer could bind to a ___ an prevent it from binding to the DNA, or it could bind to an ___ and cause it to bind to the DNA

repressor; activator

transcription factors that affect the ability of RNA polymerase to begin the transcription process may work by

resulting the binding of the transcriptional complex to the core promoter controlling the switch from the initiation to the elongation stage of transcription

the CAP site and the operator site are ___ that function in gene regulation

short DNA segments

repressors bind to

silencers

enzyme adaptation results from the synthesis of

specific proteins in response to lactose in the environment

a translational represor protein may bind to the mRNA and

stabilize a secondary structure that prevents translation

the mRNA from the trpL gene has four regions that are complementary to each other and cause the mRNA to form

stem loops

how does an effector molecule influence gene expression?

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

the product of the lacY gene is required for

the transport of lactose into the bacterial cell

the mRNA made from the trpL gene contains codons for 14 amino acids that form

the trp leader peptide

would a rescue of a mutation using a merozygote better indicate regulation of a gene by a trans-acting factor or a cis-acting element?

trans-acting factor

a protein that influences the ability of RNA polymerase to transcribe DNA into RNA is called a

transcription factor

gene regulation can occur in

translation posttranslational modification RNA processing transcription

which genes in the trp operon encode enzymes involved in tryptophan biosynthesis?

trp A, B, C, D, E

when attenuation occurs, the mRNA from the trp operon is made as a short piece that terminates shortly past the ___ gene

trpL

a gene showing a constant level of expression in all conditions over time is an

unregulated gene