Lac Operon

Question 1

What is the function of Lac Z structural gene?

Answer 1

encodes b-galactosidase

hydrolyses lactose into monosaccharides glucose and galactose

Question 2

What is the function of Lac Y structural gene?

Answer 2

encodes lactose permease to allow uptake of lactose in cell

Question 3

What is the function of Lac A structural gene?

Answer 3

encodes a thiogalactosidase transacetylate used in detoxification
acetylates non metabolisable b-galactosidase anologues

Question 4

what is Lac P?

Answer 4

promoter - enables transcription - binding of RNA polymerase

Question 5

what is Lac I?

Answer 5

Lac repressor - not part of operon but present on genome

inactivated by lactose - binds to 4 sub units and changes shape - repressor cannot bind to lac O in lactose presence

Question 6

What is Lac O?

Answer 6

operator - controls expression of structural genes - binds to lac repressor (produced by LacI)

Question 7

why is the Lac genome streamlined?

Answer 7

allows faster replication