Epigenetic control of gene expression

Question 1

What is epigenetics ?

Answer 1

That environmental factors can cause heritable changes in gene function without changing the base sequence of DNA.

Question 2

What is the Epigenome?

Answer 2

DNA and and histones are covered in chemicals, sometimes called tags. these chemicals tags form a second layer known as the epigenome.

Question 3

What are histones?

Answer 3

Proteins that the DNA is wrapped around.

Question 4

What is the importance of the epigenome?

Answer 4

It determines the shape of the DNA histone complex.

It keeps genes that are inactive in a tight packed arrangement and unwraps active genes.

Question 5

Effect of tight packed arrangement?

Answer 5

TF cannot access the DNA / binding sites so genes cannot be read keeping them switched of.
Known as epigenetic silencing.

Question 6

Effect of loose arrangement?

Answer 6

DNA is exposed and can be easily reached by TF

Question 7

The epigenome is flexible, what factors can influence it?

Answer 7

Chemical tags respond to environmental changes such as

• diet
• stress

Question 8

What is the epigenome of a cell formed from?

Answer 8

The accumulation of the signals it has received during its lifetime, it acts like a cellular membrane.

Question 9

Where can epigenetic signals come from?

Answer 9

• as a fetus signals can come from the mother

- as signals within fetus cells

Question 10

What is acetylation?

Answer 10

The addition of a acetyl group to a histone protein to decrease the positive charge of the protein and make the DNA looser.

Question 11

What is the affect of de-acetylation PT.1?

Answer 11

1. Increases the positive charge of the histone protein

2. increasing attraction to negatively charged phosphate groups on DNA

Question 12

What is the affect of de-acetylation PT.2?

Answer 12

3. increases association of DNA with histones
4. TF cannot access DNA and initiate transcription.
5. switches gene of

Question 13

What is methylation?

Answer 13

Addition of methyl group to cytosine on DNA strand.

Question 14

How does methylation affect transcription PT.1?

Answer 14

Changes shape of DNA preventing binding of transcriptional factors to DNA.

Question 15

How does methylation affect transcription PT.2?

Answer 15

Attracting proteins that condense the DNA-histone complex (by inducing deacetylation of the histones) making DNA inaccessible to TF