heritable changes in gene function without changes to base sequence of DNA
what does oestrogen bind to?
protein
what do methyl groups bind to?
dna
what do acetyl groups bind to
protein
epigenetic control= wether a gene is expressed or not
what does increased methylation do?
switches off a gene
example of epigenetic controls
inc methylation of DNA
decreased acetylation
explain increased methylation
methyl group attaches to CpG site
this changes the DNA structure meaning transcriptional machinery can't interact with gene so isnt expressed
How does inc acetylation affect gene function
causes chromatin to become less condensed
This makes it more accessible for gene
therefore gene activation
How does decreasing acetylation affect gene function
causes chromatin to condense
makes genes less accessible therefore represses transcription
What enzyme is responsible for removing acetyl groups?
histone deacetylase ( HDAC)
epigenetic changes are reversible
Drugs that reduce DNA methylation are used in chemotherapy for types of cancer that are caused by hypermethylation of tumour suppressor genes. Drugs which inhibit HDACs (the enzymes that remove acetyl groups from histones) are also being used to treat some types of cancer. This prevents deacetylation and allows genes to remain switched on. The problem is that it’s hard to make these drugs specifically target cancer cells while leaving other cells alone.
