5. Regulation of gene expression Flashcards
what are epigenomes?
they are chemical tags, which determine the shape of the histone DNA complex, and help control the transcription of genes
define epigenetics?
the study of inheritable changes in gene function that have not changed the base sequence of DNA
epigenetics can control what?
gene expression
name the two ways that epigenetics can control gene expression?
- Methylation of DNA
- Acetylation of histones
where do methyl groups attach to?
cytosine
which enzyme attaches methyl groups to cytosine?
DNA methyltransferase
when there is more methyl groups genes are turned ___
off
what does increasing methylation of DNA do?
it alters the DNA structure preventing transcription factors and enzymes binding to it
when histones are acylated, DNA ______ loosens, turning the gene __ as transcription factors and enzymes can bind to the DNA
loosens
on
when acetyl groups are _____, histones condense, meaning there is no access to DNA preventing _____
removed
transcription
name the enzyme responsible for attaching and detaching acetyl groups
histone deacetylase (HDAC)
what does hypermethylation of tumour suppressor genes cause?
prevents them from being transcribed, proteins which slow cell division will not be made, leading to possible tumours
what does hypomethylation of proto-onco genes cause?
causes them to act as oncogenes, which produce proteins which encourage cell division, stimulating cells to divide uncontrollably and form tumours
