Epigenetics

Question 1

Epigenetics

Answer 1

It refers to stable heritable traits not explained by changes in the DNA sequence

Question 2

Chromosome modifications

Answer 2

-Histones, DNA methylation
-Essential for normal development
-Can be modified by the environment
-Can be disrupted in disease

Question 3

DNA methylation

Answer 3

-Human genome contains 30,000, 000 CpGs (1%)
-CpGs are not evenly spaced across the genome
-tend to be present in clusters called CpG islands
-CpG methylation is spatially correlated
-Prevents promoters and enhancers from binding to DNA to reduce expression

Question 4

Methylation differeneces uses

Answer 4

-Determine cell type ( regulatory T cell vs Naive T Cell)
-Disrupted by disease (Cancer vs Normal)
-Affected by environment (smokers vs Non-smokers)

Question 5

EWAS

Answer 5

Epigenome-wide associated studies
-Compare lots of cases to lots of controls (often looking for small effects, eg. complex disease or environmental effects)
-Need lots of samples
-100s or 1000s of cases and controls

Question 6

How to measure methylation

Answer 6

-Bisulphite conversion
-Enrichment of methylated DNA
-Single nucleotide resolution
-Regional resolution

Question 7

Bisulphite conversion

Answer 7

A methylated site treated with bisulphite does not change (Cs protected) while an unmethylated site will cause Cs to be converted to Ts
-Creates SNP
-Chemical process
-Comparing intensity of C/T gives the proportion of methylation at single CpG

Question 8

Enrichment of methylated DNA

Answer 8

restriction enzymes
affinity

Question 9

Single necleotuide resolution

Answer 9

Array
Sequencing

Question 10

regional resolution

Answer 10

Array
sequencing