Week 6: Epigenetics Flashcards
Epigenetics
the mechanism by which changing the inherited gene expression without the change in DNA sequence
Euchromatin
prevalent in cells that are active in the transcription of many of their genes
Heterochromatin
most prevalent in cells that are less active or not active at all
When is a gene silenced?
when a gene in embedded in a highly condensed chromatin
When is a gene transcribed?
when the chromatin is more open
Epigenetic marks
Features that are not directly dictated by the genetic code, which influenced the way genes are expressed
Examples of Epigenetic marks
DNA Methylation and Modifications of Histone Proteins
DNA methylation
a covalent modification of DNA that is vital for mammalian development
What happens to transcription in highly methylated regions of chromatin?
Transcription is SUPPRESSED
What is DNA methylation mediated by?
DNA methyltransferase (DNMT) S-adenosylmethionine (SAM)
Where does DNA methylation occur in?
CpG islands
What does Histone Deacetylation do?
It causes the nucleosomes to pack tightly, which causes the genes to not be expressed; its done by histone deacetylase (HDAC) enzymes
What does Histone Acetylation do?
It causes the loose packing of nucleosomes, which causes the genes to be expressed; its done by histone acetyl transferase (HATs) enzyme
ncRNAs in epigenetic regulation
they recruit specific chromatin modifying protein complexes which leads to gene silencing
Genomic Imprinting
A parent dependent epigenetic marking; depending on the gene, either the copy from mom or the copy from dad is epigenetically silenced
Epimutations
An abnormal hereditable change that causes in abnormal epigenetic regulation
Primary Epimutation
- Occurs in the germ line and present in all the tissues of an individual
- its a direct alteration of the methylation pattern
Secondary Epimutation
- Occurs in cells in a somatic tissue
- A DNA alteration at imprinting center (IC) indirectly alters the methylation pattern
What type of inheritance of epigenetic marks might cause transcriptional dysregulation?
Transgenerational inheritance
How can acquired epigenetic disorders be obtained?
Inherited across generations
