Regulating Gene Expression and Mutation

Question 0

At what 4 levels can protein synthesis be regulated?

Answer 0

Translational
Post translational
Transcriptional
Post transcriptional

Question 1

What does an operon consist of?

Answer 1

An operator, promoter and a gene

Question 2

How do prokaryotes regulate the expression of genes

Answer 2

An operon

Question 3

What does the operator do?

Answer 3

It regulates whether or not RNA polymerase can pass through and transcribe the gene

Question 4

What is inducing gene regulation and what is an example?

Answer 4

Inducing gene regulation is where a gene is only expressed when a certain substance is present. An example would be the lac operon.

Question 5

What is the promoter?

Answer 5

The binding site for RNA polymerase

Question 6

What is an example of repressive gene regulation?

Answer 6

The trp operon (tryptophan)

Question 7

What is repressive gene regulation?

Answer 7

Repressive gene regulation is when a gene is normally active but is repressed or inactivated when that substance builds up.

Question 8

Why is gene regulation/expression so important?

Answer 8

Protein synthesis requires time, energy, and resources. The cell must manage these resources to meet the demands of the cell and maintain homeostasis.

Question 9

What role does a regulatory gene play?

Answer 9

Regulatory genes will bind to the operator in either their active or inactive form. If they bind to the operator, RNA polymerase cannot continue and transcription is stopped.

Question 10

Give an example of transcriptional regulation in eukaryotes.

Answer 10

• methyl groups can be added to silence particular genes

- histones can be tightened or loosened to affect the rate of transcription

Question 11

Give an example of post-transcriptional regulation in eukaryotes.

Answer 11

• Alternative splicing of introns
• masking protiens
• rate of degradation

Question 12

Give an example of translational regulation in eukaryotes.

Answer 12

• variation of the poly(A) tail

Question 13

Give an example of post-translational regulation in eukaryotes.

Answer 13

• polypeptide needs to be activated
• presence of hormones may alter its active state
• Ubiquitin-tagged proteins are degraded

Question 14

What is more dangerous, a frameshift or substition mutation? Why

Answer 14

Frameshift - it affects each triplet code after the point of the mutation, effectively changing every amino acid.

Question 15

What are the 3 different types of substition mutations? Describe.

Answer 15

Silent - no change in amino acid
Missense - changes the amino acid
Nonsense - results in a premature stop codon

Question 16

What is a spontaneous mutation? Give an example

Answer 16

A mutation that arises through DNA replication. An example would be DNA polymerase II not finding a mismatch base pair.

Question 17

What is an induced mutation? Give an example

Answer 17

A mutation that is caused by an environmental agent. Examples - UV, X-rays, chemicals