Lecture 16 P1

Question 1

helix-turn-helix motif

Answer 1

found in bacterial regulatory proteins

has two alpha helixes

Question 2

zinc-finger motif

Answer 2

found in eukaryotic regulatory proteins

has loop of amino acids with zinc at base

Question 3

leucine-zipper motif

Answer 3

found in eukaryotic transcription factors

Question 4

operon

Answer 4

a group of structural genes plus sequences that control transcription

Question 5

regulator gene

Answer 5

has its own promoter and encodes a regulator protein

Question 6

regulator protein

Answer 6

may bind to the operator site to regulate the transcription of mRNA

Question 7

regulatory mechanisms

Answer 7

DNA binding proteins (repressors, activators, lac operon)

attenuation

Question 8

what increases when lactose is added

Answer 8

beta galactosidase

Question 9

function of an inducer

Answer 9

prevents repressor from binding to the operator, allowing for transcription to occur

Question 10

function of a corepressor

Answer 10

binds to the repressor to allow it to bind to the operator, blocking transcription

Question 11

function of activator protein

Answer 11

inducer binds to the activator protein, allowing it to bind to the activator binding site.
transcription occurs

Question 12

two types of operons

Answer 12

sugar (lac) and amino acid (trp/arg)

Question 13

sugar operon

Answer 13

lac

is turned on when sugar is present

Question 14

amino acid operon

Answer 14

trp / arg

is turned off when amino acid is present

Question 15

negative inducible operon

Answer 15

has an active repressor that binds to the operon and halts transcription
substrate can make the repressor inactive, allowing for transcription

Question 16

positive inducible operon

Answer 16

has an inactive activator that doesn’t bind so transcription does not occur
substrate makes the activator active, transcription will occur

Question 17

negative repressor operon

Answer 17

has an inactive repressor

product in the environment makes the repressor active, halting transcription

Question 18

positive repressor operon

Answer 18

has an active activator that allows for transcription

product makes the activator inactive, halting transcription

Question 19

structure of lac operon

Answer 19

the operator overlaps the promoter and 5’ end
the operator is covered by the lac repressor
promoter includes the -10 & -35 consensus sequences until hitting the transcription start site

Question 20

absence of lactose from the environment

Answer 20

active repressor binds to the operon and halts transcription
binds at the lacO

Question 21

lacO

Answer 21

operator site for the operon

Question 22

presence of lactose in the environment

Answer 22

allolactose molecule helps induce operon to perform transcription by binding to the active repressor. this makes it inactive and unable to bind to the operon

Question 23

lacZ+ produces…

Answer 23

a functional beta galactosidase

Question 24

lacZ- produces…

Answer 24

a nonfunctional enzyme

transcription will still occur

Question 25

super repressors

Answer 25

bind to the operon no matter what

lacLs encodes SR and no transcription occurs

Question 26

mutations in lacO

Answer 26

will always block the repressor from binding to the operon

Question 27

consumptino of glucose

Answer 27

first consumed by the organism

when low, lactose will start to be produced

Question 28

CAP

Answer 28

catabolite activator protein

Question 29

CRP

Answer 29

cAMP receptor protein, binds to CAP

aids in regulating lac operon

Question 30

when glucose is low and cAMP is high

Answer 30

RNA will bind to the operon and transcription occurs

Question 31

when glucose is high and cAMP is low

Answer 31

there will be no binding to the operon