The role of the environment and epigenetics Flashcards
What are housekeeping genese
Genes that will be actively transcribed in all cells to produce essential proteins and enzymes required for cell life
What results in the production of a permanently differentiated cell
The genes expressed and therefore the specific proteins produced
What is a premotor regions function in initiation of transcription
Found immediately upstream of the gene this is known as the TATA box
specific sequences of DNA allowing the binding of
general transcription factors that allows for the recruitment of RNA polymerase II onto the gene to be transcribed
What is the role of regulatory regions?
Found upstream downstream or even between introns of genes
Specific transcription factors bind to specific sequences of DNA in these regions
collectively they form a committee that ultimately decide whether the RNA Polymerase II is activated or deactivated and thus whether transcription occurs or doesn’t
What the difference between premotor regions and regulatory regions
Premotor regions immediately upstream in TATA box general transcription factors recruit RNA polymerase
regulatory regions upstream downstream in introns
specific transcription factors bind to DNA sequences all sum together to form a committee that determines whether RNA polymerase II is activated
DNA packing in terms of histones
wrapped around nucleosomes twice makes the genes inaccessible
What is significant about histone tails
areas that can be chemically modified e.g. acetly groups can be added to lysine aa’s on the tail
this is done through enzymes that vary according to our diet, metabolism drugs we are taking
addition of groups can act as regulatory information that determines whether a gene is transcribed or silenced
What is histone tail modification and example of?
A direct epigenetic modification as nothing is happening to the DNA itself
Can be targeted therapeutically by drugs that lead to activation or inactivation fo genes through inhibition of enzymes
What is X inactivation?
inactivation of one female X chromosome very early on in development (blastocyst) as a form of dose compensation.
male Y chromosome is very gene poor one X (balances M and F)
What is gene dosage compensation?
it equalises gene expression males would have much fewer X chromosome products than females
give an example of a heritable epigenetic state?
X inactivation passed onto all subsequent daughter cells
