Chapter 14

Front 1

What processes are controlled in the regulation of gene expression?

Back 1

transcription and translation

Front 2

What are genes that encode proteins that function throughout most of the life cycle of an organism?

Back 2

housekeeping genes

Front 3

What is a small molecule that stimulates the synthesis of an inducible enzyme?

Back 3

inducer

Front 4

What is a gene whose expression level can be increased by a regulatory molecule?

Back 4

inducible gene

Front 5

What is a gene that encodes a protein whose level drops in the presence of a small molecule?

Back 5

repressible gene

Front 6

What occurs when the binding of a regulatory protein to DNA inhibits the initiation of transcription? What is that protein called?

Back 6

negative transcription control

repressor

Front 7

What occurs when the binding of a protein to DNA promotes transcription initiation? What is that protein called?

Back 7

positive transcriptional control

activator

Front 8

Where are activator-binding sites often located?

Back 8

upstream of the promoter

Front 9

What generally facilitates RNA polymerase binding?

Back 9

activator

Front 10

How are repressors and activators controlled?

Back 10

small effector molecules bind noncovalently (allosteric regulation)

Front 11

What is the inactive form of a repressor protein? When does it become active?

Back 11

aporepressor

when the corepressor binds to it

Front 12

What are the genes that code for nonregulatory polypeptides?

Back 12

structural genes

Front 13

What are often lined up together on DNA and a single, polycistronic mRNA carries all the messages?

Back 13

structural genes

Front 14

When is the lac repressor responsible for inhibiting transcription?

Back 14

lactose

Front 15

What are small effector molecules whose presence increases the level of specific enzymes?

Back 15

inducers

Front 16

What are genes that are turned "off" until turned "on?"

Back 16

inducible genes

Front 17

What are genes that are "on" until turned "off?"

Back 17

repressible genes

Front 18

Is the lac operon an inducible or repressible gene?

Back 18

inducible

Front 19

How does the lac repressor inhibit transcription?

Back 19

binds to O1 and one additional lac operator site and bends the DNA in the promoter region

Front 20

What is the segment of DNA in an operon to which the repressor protein binds?

Back 20

operator

Front 21

Where are operators usually located?

Back 21

overlaps or is downstream of the promoter

Front 22

Why are many promoters of regulated genes and operons considered "leaky?"

Back 22

there is always some low, basal level of transcription

Front 23

What is the sequence of bases in DNA that contains a promoter and one or more structural genes and often an operator or activator-binding site that controls their expression?

Back 23

operon

Front 24

What do the three genes of the lac operon code for?

Back 24

Beta-galactosidase
Beta-galactoside permease
Beta-galactoside transacetylase (unknown function)

Front 25

When is the lac operon expressed at high levels?

Back 25

in the presence of lactose but not glucose

Front 26

What reaction does Beta-galactosidase catalyze?

Back 26

lactose to allolactose

Front 27

What is the inducer of the lac operon?

Back 27

allolactose

Front 28

What functions in a global regulatory network that allows E. coli to use glucose preferentially over all other carbon and energy sources by a mechanism called catabolite repression?

Back 28

catabolite activator protein (CAP)

Front 29

What regulates the lac operon in response to the presence or absence of glucose?

Back 29

CAP

Front 30

What is the tryptophan operon regulated by?

Back 30

trp repressor

Front 31

When does the tryptophan operon function and why?

Back 31

When tryptophan is not present and must be made de novo from precursor molecules.

Front 32

What is the function of tryptophan when tryptophan levels increase?

Back 32

corepressor, binding the repressor and activating it

Front 33

What does the repressor-corepressor complex attach to, blocking transcription initiation?

Back 33

operator

Front 34

What is the ara operon regulated by?

Back 34

AraC

Front 35

What is the function of AraC when arabinose is not present?

Back 35

one molecule binds aral and another binds araO2, the two interact and cause DNA to bend, blocking transcription

Front 36

What is the function of AraC when arabinose is available?

Back 36

activator

Front 37

Is the trp operon an example of positive or negative transcriptional control?

Back 37

negative

Front 38

Is the ara operon an example of positive or negative transcriptional control?

Back 38

both

Front 39

Are most biosynthetic enzymes inducible or repressible?

Back 39

repressible

Front 40

What are two common motifs of the DNA-binding domains of regulatory proteins?

Back 40

helix-turn-helix

zinc fingers

Front 41

How do DNA-bound repressor proteins inhibit the initiation of transcription?

Back 41

by either blocking the binding or preventing the movement of DNA polymerase

Front 42

Are enhancers components of bacterial operons?

Back 42

no

Front 43

What is the domain of each subunit of the lac repressor protein?

Back 43

helix-turn-helix