W5: Intro to regulation of gene expression

Question 1

Definitions:
- Epigenetic
- Gene expression
- Post-transcriptional
- Post-translational

Answer 1

Epigenetic
- Heritable changes that do not involve changes in the DNA sequence

Gene expression
- Processes that control the turning on or off of a gene

Post-transcriptional
- Control of gene expression after the RNA molecule has been created but before translation into a protein

Post-translational
- Control of gene expression after a protein has been created

Question 2

What are the 3 stages of gene regulation?

Answer 2

Transcriptional
Post-transcriptional
Translational

Question 3

Epigenetics definition:

Answer 3

EPIGENETICS
Process of turning genes on or off i.e. up or down-regulation.
Mechanism that selectively activate or silence genes without modifying their DNA sequence

Chemical modification
of chromatin
…via histones

Acetylation
De-Acetylation
Methylation

…via DNA
Methylation

Question 4

Where are methyl groups gained from that contribute to DNA methylation?

Answer 4

Our diet

Question 5

Methylation of histones

Answer 5

1+ methyl group= Gene expression
2+ methyl groups= Histone locked tight, no expression

Question 6

When a CpG site is methylated:

Answer 6

No room for transcription factors to bind to promoter region
So no gene expression

Question 7

Methylation of DNA=

Answer 7

No gene expression

Question 8

What does histone acetylation and deacetylation do?

Answer 8

Acetylation- Opens histones and unwinds section of DNA. So transcription can occur.

Deacetylation- Closes histones

Question 9

What happens during Post-transcriptional modification?

Answer 9

Spliceosomes carry out splicing (removal of introns) and RNA editing

Question 10

How to prevent Exonucleases from ‘eating’ mRNA.

Answer 10

Add a 7 methyl guanine to one side and a poly A tail (around 250 As) to the other
(Capping at 5’ and 3’ ends)

Question 11

What happens during RNA editing?

Answer 11

Adenosine changes to Inosine
Cytosine changes to Uracil

Question 11

What happens during RNA editing?

Answer 11

Adenosine changes to Inosine
Cytosine changes to Uracil

Question 12

How does epigenetics help us in pharmacy?

Answer 12

It will help us to understand adverse drug reactions

Question 13

Define epigenetic regulation

Answer 13

• Heritable changes that do not involve changes in the DNA sequence