7.2.2 - The spliceosome and epigenetics Flashcards
What does the term epigenetics mean?
Epigenetics is the idea that there can be a changes in gene expression and phenotype involving the genome but not in terms of the order of bases in our DNA
What is splicing?
The removal of introns from pre-mRNA
Converts pre-mRNA to mRNA
What is epigenetic control?
Determining whether genes are switched on or off
This is done by the attachment or removal of chemical groups from DNA or histone (epigenetic marks)
These marks do not alter the DNA but they do alter how easy it is for enzymes to interact with the DNA and for transcription to take place
What is the epigenome?
In a cell it’s an accumulation of all the signals it has received in a lifetime and so acts a bit like cellular memory
What are 2 ways in which gene expression can be reduced (controlled)?
Increased methylation of DNA
Decreased acetylation of DNA
What are histones?
Proteins which DNA is wound around to form chromatin
Chromatin can be condensed or less condensed
What is acetylation?
Acetyl is added to lysine
This opens up the structure and activates the chromatin.
Therefore able to be transcribed.
Removing acetyl groups forms heterochromatin again.
What is methylation in epigenetic control?
A methyl group is added to lysine.
Methylation will silence a gene
Preventing transcription
What is demethylation?
Removal of a methyl group enables a gene to become active so they can be transcribed.
