Lac Operon

Question 0

What are the 2 enzymes required to metabolise lactose?

Answer 0

B- galactosidase and lactose permease

Question 1

What is enzyme induction?

Answer 1

When bacteria produce enzymes to metabolise certain nutrients only when those nutrients are present

Question 2

What is the lac operon and what are it’s parts?

Answer 2

A section of DNA within the DNA if the bacteria which consists of:
The structural genes, the operator region and the promoter region

Question 3

What are the structural genes and what do they code for?

Answer 3

Z and Y
Z codes for B-galactosidase
Y codes for lactose permease

Question 4

What is the operator region, O, and what does it do?

Answer 4

It is a length of DNA next to the structural genes which can switch them on or off

Question 5

What is the promotor region and what does it do?

Answer 5

It is a length of DNA to which the enzyme RNA polymerase binds to begin the transcription of the structural genes, Z and Y.

Question 6

How does the lac operon work when lactose is absent from the growth medium

Answer 6

The regulator gene is expressed and the repressor protein is synthesised it has 2 binding sites, one tgat binds to lactose and one to the operator region. This also partly covers part of the promotor region so RNA polymerase cannot bind so the structural genes cannot be transcribed into mRNA and therefore B-galactosidase and lactose permease cannot be synthesised

Question 7

How does the lac operon work when lactose is added to the growth medium?

Answer 7

Lactose molecules bind to the other sure on the repressor protein this causes it to change shape so it’s other binding site can no longer bind with the operator region so it breaks away from it, leaving it unblocked so RNA polymerase can now bind to it and initiate the transcription of mRNA for Z and Y to create B-galactosidase and lactose permease. These allow the bacteria to take up lactose and convert it to glucose and galactose which can then be used in the cell