ch 14 gene regulation in bacteria

Question 1

gene regulation

Answer 1

the phenomenon in which the level of gene expression can vary under different conditions

Question 2

constitutive gene

Answer 2

a gene that is not regulated and has essentially constant levels of expression over time

Question 3

repressor

Answer 3

a regulatory protein that binds to dna and inhibits transcription

Question 4

activator

Answer 4

a regulatory protein that binds to dna and increases the rate of transcription

Question 5

negative control

Answer 5

transcriptional regulation by a repressor protein

Question 6

positive control

Answer 6

transcriptional regulation by an activator protein

Question 7

inducer

Answer 7

a small effector molecule that binds to a repressor or activator and causes the rate or transcription to increase

Question 8

inducible gene

Answer 8

a gene that is regulated by an inducer, which is a small effector molecule that causes the rate of transcription to increase

Question 9

corepressor

Answer 9

a small effector molecule that binds to a repressor protein, thereby causing the repressor protein to bind to dna and inhibit transcription

Question 10

inhibitor

Answer 10

a small effector molecule that binds to an activator protein, preventing the protein from binding to the dna and thereby inhibiting transcription

Question 11

repressible gene

Answer 11

a gene that is regulated by a corepressor or inhibitor, which are small effector molecules that cause the rate of transcription to decrease

Question 12

enzyme adaptation

Answer 12

the phenomenon in which a particular enzyme appears within a living cell only after the cell has been exposed to the substrate for that enzyme

Question 13

operon

Answer 13

an arrangement in dna in which two or more genes are found within a regulatory unit that is under the transcriptional control of a single promoter

Question 14

polycistronic mrna

Answer 14

an mrna that is transcribed from an operon and encodes two or more proteins

Question 15

promoter

Answer 15

a sequence within a gene that initiates transcription

Question 16

terminator

Answer 16

a sequence within a gene that signals the end of transcription

Question 17

CAP site

Answer 17

a dna sequence that is recognized by the activator protein cap

Question 18

catabolite activator protein (CAP)

Answer 18

a genetic regulatory protein found in bacteria

Question 19

operator site

Answer 19

(also called operator) a sequence of nucleotides in bacterial dna that provides a binding site for a genetic regulatory protein

Question 20

lac repressor

Answer 20

a protein that binds to the operator site of the lac operon and inhibits transcription

Question 21

induced

Answer 21

refers to a gene that has been transcriptionally activated by an inducer

Question 22

allosteric regulation

Answer 22

the phenomenon in which a small effector molecule binds to a noncatalytic site on a protein and causes a conformational change that regulates the protein’s function

Question 23

allosteric site

Answer 23

the site on a protein where a small effector molecule binds to regulate the function of the protein

Question 24

merozygote

Answer 24

a partial diploid strain of bacteria containing F’ factor genes

Question 25

trans-effect

Answer 25

an effect on gene expression that occurs even though two dna segments are not physically adjacent to each other; mediated by diffusible genetic regulatory proteins

Question 26

trans-acting factor

Answer 26

a regulatory protein that binds to a regulatory element in dna and exerts a trans-effect

Question 27

cis-acting element

Answer 27

a sequence of dna, such as a regulatory element. that exerts a cis-effect

Question 28

cis-effect

Answer 28

an effect on gene expression due to a genetic sequence within the same chromosome and often immediately adjacent to the gene interest

Question 29

catabolite repression

Answer 29

the phenomenon in which a catabolite (ie glucose) represses the expression of certain genes (ie lac operon)

Question 30

diauxic growth

Answer 30

the sequential use of two sugars by a bacterium

Question 31

cyclic-amp

Answer 31

(also called cAMP) in bacteria, a small effector molecule that binds to cap; in eukaryotes, camp functions as a second messenger in a variety of intracellular signaling pathways

Question 32

attenuation

Answer 32

a mechanism of genetic regulation, seen in the trp operon, in which a short rna is made but its synthesis id terminated before rna polymerase can transcribe the rest of the operon

Question 33

trp repressor

Answer 33

a protein that binds to the operator site of the the trp operon and inhibits transcription

Question 34

attenuator sequence

Answer 34

a sequence found in certain operons (ie trp operon) in bacteria that stops transcription soon after it has begun

Question 35

posttranslational

Answer 35

describes events that occur after translation is completed

Question 36

posttranslational regulation

Answer 36

the functional control of proteins that are already present in the cell

Question 37

translational regulatory protein

Answer 37

a protein that regulates translation

Question 38

translational repressor

Answer 38

a protein that binds to an mrna and inhibits its ability to be translated

Question 39

antisense rna

Answer 39

an rna strand that is complementary to a strand of mrna

Question 40

feedback inhibition

Answer 40

the phenomenon in which the final product of a metabolic pathway inhibits an enzyme that acts early in the pathway

Question 41

allosteric enzyme

Answer 41

an enzyme that contains two binding sites: a catalytic site and a regulatory site

Question 42

posttranslational covalent modification

Answer 42

the chemical alteration of a protein or the covalent attachment of a molecule or functional group to a protein after it has been synthesized via ribosomes

Question 43

riboswitch

Answer 43

a mechanism for regulating transcription, translation, rna stability, and splicing in which an rna molecule can switch between two secondary conformations based on whether or not a small molecule (like tpp) binds to rna

Question 44

antiterminator

Answer 44

a secondary structure in rna that prevents early transcriptional termination