Lac Operon

Question 1

What happens when there is no lactose?

Answer 1

• the lac repressor protein binds to the operator
• prevents RNA polymerase from binding
• structural genes not transcribed
• no transcription

Question 2

What are examples of structural genes?

Answer 2

• B-galactosidase
• lactose permease

Question 3

what is a regulator gene?

Answer 3

• makes transcription factors that control the expression of other genes

Question 4

what are structural genes?

Answer 4

• makes proteins that function in the cell.
• e.g. enzymes

Question 5

what happens if lactose is present?

Answer 5

• lactose binds to the receptor protein which changes shape
• removes it from the operator
• RNA polymerase can bind to the promoter
• structural genes are expressed
  ( transcribed here + translated in the cytoplasm)
• B-galactosidase + lactose permease
  are made
• structural gene are transcribed

Question 6

what are most the genes made from?

Answer 6

• nucleotides