Topic 3C- Differentiation And Variation Flashcards
(4 cards)
What is epigenetic control?
Where chemical groups are added or removed from DNA, dictating how easy it is for the enzymes and proteins involved in transcription to interact with and transcribe genes.
This is in response to a change in environment.
What does increased methylation of DNA do?
How?
Represses a gene.
Methyl groups attach to CpG sites (where cytosine and guanine sit) and change the structure of the DNA in a way that proteins and enzymes such as RNA polymerase cannot bind to the DNA and begin transcription. This means no proteins for the DNA are produced, and the gene isn’t expressed/ is deactivated.
What does histone modification do?
What is added/removed to the histones?
Determines how condensed the chromatin in DNA is, this in turn dictates how accessible the DNA is to proteins and enzymes involved in transcription.
Acetyl groups are added/removed.
If they’re added the chromatin becomes less condensed, and the DNA is more accessible to RNA polymerase, so transcription occurs. The gene is activated.
If acetyl groups are removed, the chromatin becomes more condensed, so the DNA is less accessible to RNA polymerase, and transcription does not occur. The gene is repressed.
Can epigenetic changes be passed on?
Yes.
This way the daughter cells will have the same activated/deactivated genes, and will be better equipped to the environment subsequently.
