Epigenetics

Question 1

What is the definition of epigenetics?

Answer 1

Heritable changes in gene expression that are not a consequence of changes in DNA sequence.

Question 2

What is the importance of epigenetics?

Answer 2

Allows daughter cells to retain identity during division.

Question 3

Why is it important to study epigenetics?

Answer 3

Can be modified, environmentally and pharmacologically.
Can prevent ageing.

Question 4

What are the 2 epigenetic marks?

Answer 4

• DNA methylation
• Histone modifications

Question 5

What is DNA methylation?

Answer 5

Addition of a methyl group.

Question 6

Where does methylation take place?

Answer 6

Only at cytosine

Question 7

Why is methylation important in epigenetics?

Answer 7

Only commonly occurring covalent modification of DNA.

Question 8

Which site on cytosine does methylation occur at?

Answer 8

5

Question 9

What enzymes are involved in methylation of cytosine?

Answer 9

DNMT 1, 3a and 3b.

Question 10

What class is DNMT1?

Answer 10

Maintenance, methylation pathways can be inherited when they divide.

Question 11

What class are DNMT 3a and b?

Answer 11

Noval, add methylation to DNA which previously wasn’t.

Question 12

What is SAM?

Answer 12

Universal methylation doner, acts as a co-factor.

Question 13

What kinds of cytosines are methylated?

Answer 13

CPG dinucleotides.

Question 14

What are CpG dinucleotide?

Answer 14

Cytosine that precedes a guanine.

Question 15

Hoe many of the CpG sites in the genome are methylated?

Answer 15

70%

Question 16

What are CpG islands?

Answer 16

Areas of the genome which have higher CpG sites.

Question 17

What is the importance of methylation in repetitive regions?

Answer 17

Keeps gene expression off.
Suppression of “invading” DNA.
Suppression of inappropriate transcription.

Question 18

What is the importance of methylation on the genome?

Answer 18

Transcription factors can’t bind so those genes are not expressed.

Question 19

How many CpGs are there within the genome?

Answer 19

Genome is very CpG poor.

Question 20

Where are CpG islands?

Answer 20

Within promotor regions.

Question 21

How many active X chromosomes do women have?

Answer 21

1

Question 22

How is the other X chromosome made inactive.

Answer 22

Methylation .

Question 23

Why is it important we have only 1 functioning X chromosome?

Answer 23

Because it prevents over expression of genes.

Question 24

What are imprinted genes?

Answer 24

Genes whose expression is determined by the parent that contributed to them.

Question 25

What is the function methylation mostly?

Answer 25

Attracts huge protein complexes which change histone position and represses gene expression because transcription factors cannot bind.

Question 26

Can methylation occur at different places?

Answer 26

Yes, CpA CpT CpC.

Question 27

What is hydroxy methylation?

Answer 27

The start of demethylation but not common as it can cause cancer.

Question 28

What kinds of histone modifications are there?

Answer 28

– Acetylation – Methylation – Phosphorylation – Ubiquitination

Question 29

Where does the histone modification take place?

Answer 29

On their funky little tails.

Question 30

What happens when acetylation occurs on the histone?

Answer 30

Activation Decompaction DNA becomes permissive

Question 31

What happens when methylation occurs on the histone? K9 – H3 and K27 – H3

Answer 31

Inactivation Compaction Non-Permissive

Question 32

What is epigenetic drift?

Answer 32

The accuracy of which is DNA is methylated is much lower than DNA replication.

Question 33

What happens to DNA methylation with age?

Answer 33

DNA methylation pattern breaks down, reduction of CpG islands which leads to incorrect cell function.

Question 34

What is frailty?

Answer 34

Can be defined as a syndrome of decreased reserve and resistance to stressors, resulting from cumulative declines across multiple physiologic systems and causing vulnerability to adverse outcomes.

Question 35

What is the importance of methylation for frailty?

Answer 35

The more methylation you have the less frailty you have.

Question 36

Can methylation be used to predict age?

Answer 36

Clear correlation gives an indication of age based on methylation. BUT only biological age.

Question 37

What can happen when you get abnormal methylation?

Answer 37

You become more prone to developing cancer.

Question 38

Why is DNA methylation important in regards to ageing?

Answer 38

If you prevent methylation you can sometimes prevent age-related diseases.

Question 39

What are HATs?

Answer 39

Histone acetyltransferase