L19: Epigenetics

Question 1

Define: epigenetics

Answer 1

Heritable changes in gene expression and cellular phenotype that are independent of changes in the underlying DNA sequence.

Question 2

The human genome contains approximately how many genes?

Answer 2

20,000–25,000

Question 3

What percentage of the human genome is composed of genes?

Answer 3

1-2%

Question 4

The fundamental unit of chromatin is

Answer 4

nucleosome

Question 5

Composition of nucleosome

Answer 5

146 bp DNA wrapped around octameric histone core consisting of two molecules each of H2A, H2B, H3, H4

Question 6

Heterochromatin

Answer 6

Highly condensed, inactive regions

Question 7

Euchromatin

Answer 7

Unwound open conformation, active transcription

Question 8

Trimethylated lysine 4 on histone 3 is associated with

Answer 8

transcriptionally active genes

Question 9

trimethylated lysine 9 on histone 3 is associated with

Answer 9

inactive genes

Question 10

DNA methylation mode of action

Answer 10

Methyl group attracts methyl-binding proteins, adding bulk to the DNA and therefore blocking access to transcription factors

Question 11

Acetylation of histones generally ___ transcription

Answer 11

increases