Chapter 16 Prokaryotic regulation

Question 1

What does Beta Galactadisadase do? Where is it located?

Answer 1

Breaks glycosidic bond, lac z

Question 2

What does beta galactoside permease do? Where is it located?

Answer 2

allows more lactose in (attaches to wall and pumps), lac y

Question 3

What does beta calactosidase trancetylase do? Where is it located?

Answer 3

transfers bgal and acetyl

Question 4

What does the repressor do? How does it inactivate and activate the lac operon?

Answer 4

binds to the operator and inactivates, when lactos binds to the repressor it releases from the operator and lac operon is acive

Question 5

How do camp and cap work? where does it bind to?

Answer 5

cap can bind to the activator site and then have camp bind to it (effector) to make RNA polymerase bind better to the promoter site, enhancing the rate of transcription

Question 6

give two examples of effectors. What does it do?

Answer 6

camp and lactose
camp enhances transcription, lactose binds to the repressor and remove it from the operator

Question 7

how does cap activate? inactivate?

Answer 7

activates when glucose is low, camp increases
deactivates when glucose is high, camp decreases

Question 8

What are inducers?

Answer 8

inactive repressors, ex lactose

Question 9

What are the three structural genes?

Answer 9

lacx, lac y, lac a

Question 10

The lac I gene encodes the ______ that is inactivated by the _______

Answer 10

repressor, inducer

Question 11

What is the I+ gene? What is the I- gene? Which is recessive and which is trans?

Answer 11

I+ normal regulation needs inducer
I- constitutive mutation, does not need inducer

Question 12

Are P- non inducible in any condition?

Answer 12

yes!

Question 13

What are 3 examples of the effect of RNA on transcription?

Answer 13

attenuation, riboswictches, sRNA

Question 14

What is attenuation?

Answer 14

termination of transcription

Question 15

What are the two different loops in attenuation?

Answer 15

antiterminator - absence of tryptophan (2-3), the inducer (tryptophan) cannot bind to the repressor and it does not attach to the operon
terminator - presence of tryptophan (3-4), the inducer (tryptophan) attaches to operon and attaches to the operon, inactivating transcription

Question 16

high tryptophan does….

Answer 16

makes ribosome translate faster, however, it moves too fast and 2 cannot pair with 3

Question 17

What do riboswitches do?

Answer 17

bidns with small ligans at site can causes second RNA domain, can cause antitermination or termination

Question 18

_______ + ________ makes a riboswitch conformational change and _______ transciption

Answer 18

ligand + ligand site, inactivate

Question 19

How does sRNA activate translation?

Answer 19

unmasks the ribose binding site after the dna has folded back on itself, can be negative when no folding back has occured bc it blocks the rbs