Epigenetic control of gene expression

Question 1

The epigenome

Answer 1

-DNA is wrapped around histones
-These are covered in chemical tabs which form the epigenome
-Tightly pack genes=inactive
-Unwrapped DNA is exposed so expressed

Question 2

DNA methylation

Answer 2

A methyl group binds to cytosines which suppresses transcription
Added from
-Exercise
-Stress
-Smoking

Question 3

DNA acetylation

Answer 3

-Acetyl groups bind to histones
-Weakens the attraction between histones and DNA
-Making it easier for RNA polymerase to bind
-Stimulating transcription

Question 4

Influence of mothers on epigenome

Answer 4

-Nutrition from mother to fetus shapes the epigenome, hormones also affect it
-A woman who smokes while pregnant induces epigenetics in; her self, unborn daughter, and her daughter’s reproductive cells

Question 5

Implications of epigenetics on cancer

Answer 5

• Mitosis is controlled by 2 gene groups
  -Proto-oncogenes control cell division
  -Tumour suppressor genes slow cell division + promote apoptosis in cells with DNA damage
  -When proto-oncogene is mutated it results in cells dividing too quickly
  -If a tumor suppressor gene is mutated it is inactivated, so cell division increases.

Question 6

Mylnation and cancer cells

Answer 6

When tumor suppressor genes are hyper-methylated, they become inactivated, so can’t:
-Keep cell growth in check
-repair damaged DN
-Initiate apoptosis

Question 6

Too little myelination causes

Answer 6

-Activation of oncogenes that promote cell growth
-Chromosome instability: highly active DNA is more likely to be duplicated, deleted, and moved