Epigenetics and Gene Expression in Eukaryotes Flashcards
(14 cards)
What is epigenetics?
Changes in gene function without changes in base sequence of DNA
What may these changes in epigenetics be caused by?
Aspects of the environment
What can epigenetics do?
Increase or decrease gene expression
What two changes are included in epigenetics?
Increased methylation of DNA, decreased acetylation of associated histones
Does increased methylation of DNA mean more or less expression?
Less expression
When does increased methylation occur?
When a methyl group attaches to the DNA sequence of a gene
What does the methyl group attach to?
A cytosine when it is next to a guanine (CpG site)
What does this methylation do?
Inhibits transcription by preventing the binding of transcription factors to the promotor sequence
Does decreased acetylation of histones mean more or less expression?
More expression
What is DNA wrapped around in eukaryotes?
Histones to form chromatin
What happens when histones are more acetylated?
Chromatin is less condensed so transcription factors can more easily access DNA
Can epigenetics be reversed?
Yes
How can cancer form from hypermethylation?
Tumour suppressor genes are not transcribed
How can cancer form from hypomethylation?
Proto-oncogenes are continuously transcribed which increases proteins involved in cell division
