Gene Expression- Epigenetics Flashcards
What can epigenetic control determine in eukaryotes?
Whether a gene is switched on or off (whether a gene is expressed or not)
How does epigenetic control work?
Through the attachment or removal of chemical groups to or from DNA or histone proteins
Do epigenetic marks alter the base sequence of DNA?
No, they alter how easy it is for enzymes and other proteins needed for transcription to interact with and transcribe the DNA
What roles do epigenetic changes to gene expression play?
A role in lots of normal cellular processes and can also occur in response to changes in the environment
How do organisms inherit their DNA base sequence?
From their parents
How are epigenetic marks involved in inheritance?
Most epigenetic marks on the DNA are removed between generations, but some escape the removal process and are passed on to offspring
What does inheriting epigenetic marks mean?
Expression of some genes in the offspring can be affected by environmental changes that affected their parents or grandparents
What is methylation?
When a methyl group is attached to the DNA coding for a gene
Where does the methyl group attach in methylation?
At a CpG site, which is where a cytosine and guanine base are next to each other in the DNA
How is methylation involved in epigenetic control?
Increased methylation changes the DNA structure so that the transcriptional machinery can’t interact with the gene so that the gene is not expressed
What are histones?
Proteins that DNA wraps around to form chromatin, which makes up chromosomes
What can chromatin be?
Highly condensed or less condensed
What is the effect of how condensed chromatin is?
Affects the accessibility of the DNA and whether or not it can be transcribed
How can histones be epigenetically modified?
By the addition or removal of acetyl groups
What is the state of the chromatin when histones are acetylated and what does this mean?
Less condensed which means that transcriptional machinery can access the DNA, allowing genes to be transcribed
