Epigenetics

Question 1

Housekeeping genes

Answer 1

Some genes need to be on in every cell, they are known as housekeeping

Eg
ATP for respiration

Question 2

What is a chromosome

Answer 2

Long linear DNA associated with histones

Question 3

Euchromatin ands heterochromatin

Answer 3

Loosely and tightly coiled

Question 4

Epigenetics

Answer 4

Heritable change in gene function without changing base sequence

Question 5

Factors affecting epigenetics

Answer 5

-diet
-disease exposure
- toxic chemicals
-socioeconomic background
-psychology state

Question 6

Epigenome

Answer 6

Tags:chemicals covering DNA and histones
They determine the shape of histone DNA complex

Answer 7

Tags cause DNA to cool tightly or loosely
Inactive genes can be wrapped tightly

Question 8

Decreased acetylation

Answer 8

-Histone Deacetylase removes acetyl groups from histones
-Increases the positive charges on histones
-Increases their attraction to the negative phosphate groups.
-Association between histone and DNA is stronger
-Tighter coiling
-Therefore, transcription of gene less likely

Question 9

Epigenetics model answer

Answer 9

• Histone Deacetylase removes acetyl groups from histones
. Increases the positive charges on histones
• Increases their attraction to the negative phosphate groups.
• Association between histone and DNA is stronger so Tighter coiling
• Transcription factors and RNA
Polymerase can’t bind as easily
Transcription of gene less likely and gene is switched off

Question 10

Increased methylation

Answer 10

• Methylation is addition of methyl group to molecules to cytosine bases of DNA
• DNA coils more tightly
• Transcription factors cannot bind easily
• Transcription of gene less likely
Le. gene is switched off

Question 11

How would increased methylation cause a problem for tumour suppressor genes?

Answer 11

-tumour expression gene can’t be expressed
-no transcription of it
-can’t regulate mitosis
-tumour

Question 12

Increased methylation model answer

Answer 12

Increased Methylation
• Methylation is addition of methyl group to cytosine bases of DNA
• DNA colls more tightly
• Transcription factors and RNA
Polymerase can’t bind as easily
• Transcription of gene less likely and gene is switched off
Epigenetics often impacts tumour suppressor genes by turning them off leading to uncontrolled cell division