Epigenetics Flashcards
Define “epigenome”
A multitude of chemical markers influencing which genes are transcribed in a particular cell according to environment
Define “epigenetics”
Changes to gene expression caused by environmental factors - without changing base sequence of DNA
What are the 2 ways the epigenome can be changed?
- Increased methylation of DNA
- Acetylation of histones
How does increased methylation change the epigenome? 5
- Methyl group attaches to DNA coding for gene at the CpG site
- Increased methylation changes DNA structure
- Prevents transcriptional enzymes e.g RNA polymerase binding to gene
- mRNA cannot be transcribed
- Gene not expressed
What is the CpG site?
Where C and G are next to each other in the DNA promoter region
What are histones?
Proteins DNA coils around to form chromatin which makes chromosomes
How does the addition of acetyl groups to histone tails affect the epigenome?
- Chromatin is less condensed
- Transcription factors e.g RNA polymerase bind to the gene
- mRNA is transcribed
- Gene is activated
How does the removal of acetyl groups from histone tails affect the epigenome?
- Chromatin is more condensed
- Transcription factors e.g RNA polyermase cannot bind to gene
- mRNA is not transcribed
- Gene is not activated
What triggers changes to the epigenome?
Environmental changes e.g pollution and food availability
How can epigenetic changes be passed on to the offspring? 3
- When a cell divides and replicates epigenetic changes are passed on to daughter cells
- Epigenetic changes activated/deactivated in original cell = activated/deactivated in daughter cell
- Daughter cell equipped to deal with the environment in the same way
How do cells become specialised? 7
- Correct stimulus e.g. chemical
- Cause some genes to be active and others inactive
- Only the active genes are transcribed
- mRNA made only at active genes
- Protein made
- Cell structure / function determined
- Cell permanently modified
