Gene expression Flashcards
How does epigenome modifcations affect gene expression
Methylation – attachment of a methyl group to the promotor inhibits gene expression as it prevents transcription
Histone modification chemical groups are added to the histone tail addition of an acetyl group changing the interaction and how tightly between histone and DNA in winded, Increases gene expression.
How can factors that cause changes in our epigenome
Diet/pollution/ lifestyle/smoking/ alcohol/chemical exposure.
This may cause a chemical signal to which cause DNA to be wrapped around the histone tightly causing a main gene to be switched off and inactivated, preventing transcription to mRNA, stopping gene making key protein.
How may Histone modification affect epigenome
The binding of epigenetic markers to histone tails determines how tightly DNA winds around histone proteins. If very tight, gene is inactive because transcription to mRNA cannot occur so gene cannot make protien and is switched off.
How may DNA methylation affect epigenome
Methyl and acetyl groups such as cytosine attaches to DNA, preventing RNA polymerase binding, preventing trabnscription, so gene is switched off and is not expressed.
Describe the structre of DNA
DNA is so long it must be packaged/ organised. - It does this by coiling around protein structures called histones
How is a gene switched on (lac operon model) in prokaryoktes etc. E coli , when lactose is avaible?
E coli produced B-galactosidase, breaking down carbohydrates lactose to glucose and galactose.
When lactose is available lactose binds repressor molecule and repressor is prevented form binding to DNA and B glactose gene is expressed.
Therefore mRNA is transcriped and translation produces the enzyme
What happens if lactose isn’t avalible when gene is switched on?
Lactose repressor molecule binds to DNBA and transcripition of B galactodase is prevented, preventing the B galactose gen form being expressed
How are genes switched on and off in eukaryotes?
RNA polyermase binds to the gene that is going to be transcribed on the promoter region. gene remains switched off until RNA polyermase binds to promotor region successifully. Allows for transcription to mRNA to occur….
How can trancuiptions of a gene be prevent
This can happen by protein repressor molecules attaching to promotor DNA region blocking site or repressor molecules could attach to proteins and gene is switched off and not transcribed in cell.
Whats FOP ?
One of the genes in the white blood cells aren’t switched off.
This is a problem because when damage to tissue cells, white blood cells produce a protein which diffuse into surrounding muscle cells which cause the muscle cells to start expressing other genes, turning them into bone cells.
How do you know which chromosome has a wekaer linkage
The one thats furthest apart as more likely tk be seperated during crossing over
