EPIGENETICWS Flashcards
What are epigenetic mechanisms
Regulators of gene expression that can create potentially heritable changes in gene expression without changing the nucleotide sequence e.g infectious agents, toxins
What is phenotype determined by?
Genotype and environment
What are alleles?
Different versions of the same gene
What are housekeeping genes?
Genes that are expressed in all cells and are necessary for cell function e.g histones, RNA polymerase
What is a promoter?
A 5’ regulatory sequence that controls transcription initiation
Where are enhancers found?
At a distance from the gene
How do TF influence RNA
- RNA doesn’t recognise transcription start sites which is the first base incorporated into the RNA chain
- TF recognise and bind the gene promoter to the gene
- TF recruits RNA polymerase
- This allows for a low level/ basal level of transcription
Where do gene regulatory proteins bind to?
Enhancer region
What is a nucleosome?
DNA wrapped around a protein core which is made from 8 histone proteins.
- H2A
- H2B
- H3 (x2)
- H4 (x2)
What are the three wats in which epigenetics are influenced?
- Gene expression
- acetylation and deacetylation of histone proteins
- X- inactivation
What 3 factors affect acetylation of histones?
- Environmental factors e.g diet
- Therapeutic drugs
- Cell metabolism
What are nucleosome modifications?
- Involved in turning genes on or off
What is X inactivation?
X- inactivation is random. In embryonic development one of the two X chromosomes is randomly permanently inactivated in cells other than eggs. This ensures that females, like males get one copy the X chromosome in each cell.
