Gene regulation in prokaryotes

Question 1

Constitutively expressed genes

Answer 1

expressed in most cells (DNA replication, transcription and translation)

Question 2

Regulated genes

Answer 2

are inducible or repressible

Question 3

Operon

Answer 3

genes whose products are involved in the same metabolic pathway

Question 4

Components of operon

Answer 4

repressor
effector molecule 
operator 
promoter
structural genes

Question 5

repressor

Answer 5

represses the expression of structural genes

Question 6

effector molecule

Answer 6

regualtes binding of the operon to the operator sequence

Question 7

promoter

Answer 7

controls transcription

Question 8

structural genes

Answer 8

Z, Y, A required for lactose metabolism

Question 9

regulatory gene

Answer 9

lac l codes for lac operon repressor protein

Question 10

operator

Answer 10

lac O - DNA binding site for the repressor protein

Question 11

lac Y

Answer 11

lactose permease - transport of lactose from the environment

Question 12

lac Z

Answer 12

B-galactosidase - cleave lactose into glucose and galactose - converts lactose to allolactose

Question 13

lac A

Answer 13

function unknown (maybe toxicity)

Question 14

lac l

Answer 14

encodes lac repressor

Question 15

lac O

Answer 15

lac operator -controls the lac operon through repressor binding

Question 16

allolactose

Answer 16

binds the lac repressor inducing a conformational change

Question 17

cAMP

Answer 17

regulates lac operon activity via binding to CAP (catabolite activator protein) that binds to the lac operator

Question 18

cAMP/CAP

Answer 18

helps orient RNA polymerase and exerts positive control over transcription of the lac operon

Question 19

feedback inhibition

Answer 19

the final product of a biosynthetic pathway inhibits the activity of the first enzyme in the pathway shutting it off