Epigenetics

Question 1

What is epigenetics?

Answer 1

Heritable changes in gene function, without changes to the BASE sequence of DNA

Question 2

Heritable meaning

Answer 2

This can be inherited by offspring

Question 3

What causes epigenetics?

Answer 3

Changes in the environment that inhibit transcription of specific genes (by increased methylation of DNA and decreased acetylation of histone proteins)

Question 4

What is the consequence of epigenetic changes?

Answer 4

Changes to phenotype of an organism because transcription of specific genes is INHIBITED SO will not express this gene in the phenotype if a polypeptide cant be translated without the mRNA produced

Question 5

What are the 2 factors that will inhibit transcription?

Answer 5

Increased methylation of DNA
Decreased acetylation of histone proteins associated with DNA

Question 6

Why does increased methylation of DNA inhibit transcription?

Answer 6

RNA polymerase will struggle to bind to DNA with more methyl groups so cannot transcribe it
And if methyl groups bind to promoter, this prevents transcription factor binding so RNA not stimulated to transcribe gene in the first place

Question 7

If methyl groups are removed from DNA then?

Answer 7

The gene can be transcribed:)
Because promoter can have transcription factor bind to it and RNA polymerase can actually bind = RNA polymerase activated to transcribe

Question 8

Why does decreased acetylation of associated histone proteins inhibit transcription?

Answer 8

LESS ACETYLATION = DNA IS WRAPPED TIGHTER AROUND HISTONES
So promoter is not accessible for transcription factors to bind to it so RNA not stimulated to transcribe the gene
And RNA polymerase cant bind to DNA to transcribe anyway

Question 9

If acetyl groups are added to histone groups? (increased acetylation)

Answer 9

DNA wrapped looser around histone proteins so transcription factor can actually bind to promoter ( BECAUSE ITS ACCESSIBLE) and RNA polymerase can actually bind to gene
RNA polymerase can transcribe gene

Question 10

Source of acetyl groups

Answer 10

From acetyl co enzyme A from link reaction of respiration

Question 11

Memory tool for epigenetics

Answer 11

InT IMDNA DAH
Inhibit transcription by increased methylation of DNA and decreased acetylation of histone proteins