Epigenetics Flashcards
What are transcription factors?
DNA-binding proteins that recognise a short target DNA sequence and bring in other proteins to stimulate expression of a gene
What are enhancers?
Promoter-like sequences that can be located upto 1Kb away from the gene they control and can be upstream or down stream. DNA lopping brings them into contact with the promoter and mediator complex to control gene expression. Genes are often controlled by series of tissue specific enhancers. Location of enhancer Action could be investigated by cloning it upstream of a LacZ expression construct and visualising LacZ expression in mouse embryo
Which part of histones are covalently modified?
N-terminal parts of histone molecules that provide from nucleosome
Can be methylated, acetylated, phosphorylated, etc.
How is heterochromatin epigenetically characterised?
H3K9me3
What carries out DNA methylation?
DNA Methyltransferases
Only cytosine is commonly methylated - to form 5-methylcytosine
Outline the main mechanism for Epigenetic memory
DNMT1 replicates the Epigenetic markers of parental strand onto daughter strand of DNA to maintain Epigenetic pattern in daughter cells
What is X inactivation?
Dosage compensation to ensure that every cell has only one functional copy of the X chromosome. Early in embryogenesis every cell inactivates it’s X chromosomes to leave behind only one. Which is inactivated is remembered in daughter cells. Leading to mosaicism across the body depending which was turned off in the originating cell.
What is imprinting?
Paternal origin matters for a few of the 20,000 genes in the genome. Some genes from mother are epigenetically turned off and some are turned off from the father. This is reversible in offspring so the correct pattern is passed on. THe genes usually are involved in metabolism and growth and combat each other to achieve balance. Paternal encourages growth and maternal discourages growth.
