Epigenetics

Question 1

3 main forms of epigenetics?

Answer 1

1. Methylation of hydroxymethylation of C
2. Inherited changes in chromatin structure (in eukaryotes)
3. Non-coding (nc) RNA that stably assoc w/ chromatin

Question 2

Most common dyad that is methylated?

Answer 2

5’-CpG-3’

Question 3

What are some inherited changes in chromatin structure? (3)

Answer 3

• mod of chromatin proteins
• alterations in histone content
• changes in which proteins are stably incorporated into chromatin

Question 4

Relationship b/w methylation and cancer?

Answer 4

• abnormal methylation patters in DNA are a big contributor to cancer

Question 5

In what tissue are there high amt’s of 5hmC in DNA?

Answer 5

• Purkinje fibers

- important for neural function

Question 6

T/F: CpG almost always methylated/unmethylated on both strands

Answer 6

True

Question 7

When are most DNA methylation patterns est?

Answer 7

During embrogenesis

Question 8

When does the methylation rxn usually happen?

Answer 8

Soon after DNA synth

Question 9

What is de novo methylation?

Answer 9

Methylation of a previously unmethylated CpG pair

Question 10

What is maintenance methylation?

Answer 10

• methylate a CpG pair in which one strand is already methylated

Question 11

What 3 genes encode mammalian DNA methyltransferases (DNMTs)? Roles?

Answer 11

1. DNMT1 = main enzyme for maintenance
2. DNMT3A = de novo methylation
3. DNMT3B = de novo methylation

Question 12

What leads to myeloid neoplasms?

Answer 12

Loss of much DNA 5hmC

Question 13

T/F: methylated sites are protective against mutation

Answer 13

False, they are hotspots for mutation

Question 14

First disease linked to abnormal methylation?

Answer 14

• Immunodeficiency, Centromeric region instability, Facial anomalies syndrome (ICF)
• freq anomalies in chromo 1/16 lymphoid metaphases