DNA methylation

Question 1

DNA methylation: two pathways

Answer 1

DNMT3: de novo - methyl of 5º carbon of cytosine (5-methylcytosine)

DNMT1: maintenance (cell division)

Question 2

Where? Consequences?

Answer 2

gene promoter: transcriptional factors can´t bind and access DNA - no trancription (not all of them)

body: proteins bind to methylated DNA and repress transcription and lower efficiency promoters (more efficiency and expression)

Question 3

X- chr inactivation

Answer 3

Xist coats the inactivated X
repressive histone modifications and hypermethylation of CpG promoter regions

Question 4

development

Answer 4

2 methylations and 2 demethylations

Question 5

DNA demethylation

Answer 5

ten-eleven translocation (TET) - transforms 5-methylcytosine in 5-hydroxymethylcytosine (active demethylation (abasic site - normal cytosine)
-90% DNMT activity and maintenance

Question 6

environmental links

Answer 6

cell memory = present and past exposures - long lasting epigenic changrd (transgenerational inheritance)
mal nutrition, heavy metals, pesticides

Question 7

Bisulfite treatment

Answer 7

promotes deamination of cytosine to uracil whereas methylated cytosines do not react with bisulfite and are therefore resistant to deamination. during PCR or direct short-read sequencing, uracil
will be converted to thymine.