Epigenetic control of gene expression Flashcards
What does epigenetic control do?
Determines whether a genes is switched on/off and whether it is expressed
What type of cells does epigenetic control happen in?
Eukaryotes
How does epigenetic control work?
It works through the attachment or removal of chemical groups to or from the DNA or histone proteins.
What doe the epigenetic marks do?
Alter how easy it is for the enzyme and other proteins needed for transcription to interact with and transcribe the DNA.
What happens if the epigenetic marks on the DNA are passed onto offspring?
The expression of some genes in the offspring can be affected by environmental changes that affected their parents or grandparents
What does increased methylation of a gene do?
Switches off a gene.
It changes the DNA structure so that the transcriptional machinery can’t interact with the gene. The gene isn’t expressed
Explain the process of methylenation of DNA
A methyl group is attached to the DNA coding for a gene. The group always attaches at a CpG site where there is a cytosine and guanine base next to each other.
Explain the process of decreased acetylation of histones
- histones can be epigenetically modified by the addition or removal of acetyl groups.
- when histones are acetylated the chromatin is less condensed. This means that the transcriptional machinery can access the DNA allowing genes to be transcribed.
- when acetyl groups are removed from the histones, the chromatin becomes highly condensed and genes in the DNA can’t be transcribed because the transcriptional machinery can’t physically access them.
- histone deacetylase (HDAC) enzymes are responsible for removing acetyl groups
Why is it good that epigenetic changes are reversible?
It makes them good targets for new drugs to combat new diseases they cause
What are the drugs designed to do?
Counteract the epigenetic changes that cause the diseases
