Epigenetics

Question 1

Define - epigenetics

Answer 1

Study of How gene activity can be controlled without changing the DNA sequence itself

It regulates the genes without changing the DNA – turns it on or off

Behavioural and environmental factors cause these changes.

Question 2

Explain some features/ characteristics of epigenetics

Answer 2

1. Can be reversible
2. Do not change DNA sequence
3. Change how the DNA sequence is ‘read’

Question 3

What are three epigenetic factors (tags)?

Answer 3

Hereditary factors that are independent of the actual DNA sequence.
1. Chemical tags added to DNA eg. Methylation
2. Alteration of histones
3. Alteration of regulatory RNAs

Question 4

What is DNA methylation?

Answer 4

• Adding chemical group to tag the DNA
• Can tag cytosine with methyl group – change behaviour of DNA if enough it switches off DNA.
• Eg. Haemoglobin gene made by cells not methylated

Question 5

What is histones modification?

Answer 5

• Binding of epigenetic factors to histones (tails) alters extent to DNA wrapped around histones and ability of gene in to DNA to be activated
• Makes Gene more tightly bound so can not be accessed and read so switched off

Question 6

WHat are epigenetic effects? Give examples

Answer 6

Promoting or inhibiting gene activation

Toxic chemicals, diet, physiological state, microbiome, therapeutic drugs, disease, infection – viral/bacterial and exercise.

Question 7

How can TB be linked to epigenetics?

Answer 7

• Microbiome Change
• Cause changes to histones in immune cells to turn off IL-12B gene to weaken immune system and improves survival of TB.

Question 8

What can the Dutch Hunger Winter Famine be linked to epigenetics?

Answer 8

• Offspring of Pregnancy during famine famine strugglers had increased incidence of obesity, heart disease, schizophrenia, type 2 diabetes.
• They had significant levels of extra DNA methylation compared to non-famine siblings