Cellular Control

Question 1

What are the three types of cellular control to regulate gene expression?

Question 2

What does it mean if a gene is expressed?

Answer 2

Transcription and translation occur

Question 3

What is a structural gene?

Answer 3

A gene which codes for a protein that has a function in the cell

Question 4

What is a regulatory gene?

Answer 4

A gene which codes for a protein that controls the structural gene expression

Question 5

What is a promoter?

Answer 5

A DNA sequence between the regulatory and first structural gene which acts as the binding site for RNA polymerase

Question 6

Roughly, how does repression occur?

Answer 6

The regulatory gene produces a transcription factor/ repressor protein which binds to the operator. This prevents RNA polymerase from binding to the promoter transcribing the structural genes.

Question 7

What does an operon contain?

Answer 7

Promoter, operator and a cluster of structural genes

It is a cluster of structural genes under the control of one promoter

Question 8

What is contained in the lac operon?

Answer 8

LacI - Lactose inhibitor gene
Promoter
LacO - LacOperon Operator
LacZ -
LacY -
LacA -

Question 9

In eukaryotic operons, they don’t contain an…

Answer 9

Operator

Transcription factors always stimulate gene expression and bind to promoters

Hormones can activate inactive transcription factors

Question 10

What are the differences between transcriptional-control of gene expression in prokaryotes and eukaryotes?

• RNA Polymerase
• Binding site of transcription factors
• Effect of transcription factors
• Name of transcription factors

Answer 10

Prokaryotes:

• Can bind to promoter without transcription factors
• Operator
• Inhibits transcription
• Repressor protein

Eukaryotes:

• Can’t bind to promoter without transcription factors
• Promoter
• Stimulates transcription
• Transcription factor