Gene Expression - Lecture 1

Question 1

What are constitutively expressed genes?

Answer 1

genes that are continuously expressed in most cells

Question 2

What kind of gene is the trp operon?

Answer 2

repressible gene

Question 3

What is an operon?

Answer 3

a group of structural genes that control transcription

Question 4

What is a regulatory gene?

Answer 4

encodes regulatory protein that can bind to the operator side to regulate mRNA transcription

Question 5

What are negative inducible operons?

Answer 5

when the regulator protein binds only to the operator which prevents RNA polymerase from transcribing

Question 6

What occurs in a negative inducible operon when there is no inducer present?

Answer 6

the operon doesn’t need to be expressed so it is shut off, regulatory protein binds to operator DNA sequence and blocks operon so transcription do not occur

Question 7

What occurs in a negative inducible operon when there is an inducer present?

Answer 7

the inducer binds to regulator so the regulator cannot bind to operator so transcription takes place

Question 8

What are negative repressible operons?

Answer 8

occurs when a regulator protein needs to be activated by a product before it can bind to the operon to prevent transcription

Question 9

What occurs in a negative inducible operon when no product U is present?

Answer 9

regulator protein does not bind to operator and transcription takes place

Question 10

What occurs in a negative inducible operon when product U is present?

Answer 10

product U binds to regulator protein so transcription cannot occur

Question 11

What is a positive control operon?

Answer 11

activator binds to DNA and helps RNA polymerase with transcription