Gene Regulation

Question 1

Can transcription be positively or negatively regulated?

Answer 1

It can be both with regulator binding

Question 2

What are the two types of transcription regulators?

Answer 2

Activators and Repressors

Question 3

Activator

Answer 3

Causes transcription to go/happen

Question 4

Repressor

Answer 4

Binds to an operator and stops transcription

Question 5

What enzymes does E. coli use to uptake & catabolise lactose?

Answer 5

Lac permease and b galactosidase

Question 6

Where can the genes for lactose catabolism be found?

Answer 6

Lac Operon

Question 7

What is the Lac Operon?

Answer 7

It is an inducible operon that is controlled by a repressor/negative regulator

Question 8

What pathways are glucose and galactose found in?

Answer 8

Glycolysis, ED, EMP, PPP

Question 9

What does CRP bound to cyclic AMP do?

Answer 9

Positively regulates the weak Lac promoter and high levels of expression

Question 10

What is the state of the Lac operon in high lactose environments?

Answer 10

Induced (on)

Question 11

What is the state of the Lac operon in low/no lactose environments?

Answer 11

Repressed (off)

Question 12

What affects the levels of cAMP in a cell?

Answer 12

The presence or absence of glucose
Low glucose; High cAMP

Question 13

What effect does cAMP-CRP have on DNA?

Answer 13

When it is bound it creates a bend and interactions with RNA polymerase assist with the initiation of transcription

Question 14

What binds to the Lac regulatory region (w/ a specific DNA sequence)?

Answer 14

RNA polymerase, cAMP-CRP and Lac repressor

Question 15

T/F - Binding of the Lac repressor & cAMP-CRP around the promoter determine operon transcription?

Answer 15

True

Question 16

If given the choice of lactose & glucose what do cells use up first? Why?

Answer 16

Glucose b/c the uptake of glucose blocks lactose uptake - Inducer exclusion

Question 17

What is the Ara operon for?

Answer 17

Arabinose catabolism

Question 18

How is the ara operon controlled?

Answer 18

It is an inducible operon that is controlled with a protein that is both an inducer and a repressor

Question 19

araC

Answer 19

Dimer that is a positive & negative regulator of the ara operon

Question 20

How is araC both an inducer & repressor?

Answer 20

Arabinose binds directly to the structure and causes a change within the molecule that dictates how it interacts with the operon

Question 21

Without arabinose is the ara operon induced or repressed?

Answer 21

Repressed

Question 22

With arabinose is the ara operon induced or repressed?

Answer 22

Induced