RNA interferences and tumour supressor genes Flashcards
what is RNA interference
controlling gene expression by preventing transLATION
siRNA key point:
describe how siRNA prevents translation
small interfering RNA
- double stranded
- combines with a proteins to form an siRNA-protein complex
- becomes single stranded by breaking its H-bonds
- has complementary bases to target mRNA
- siRNA-protein complex breaks down mRNA into pieces
- preventing translation
describe how microRNA prevent translation? (3)
what can microRNA do that siRNA cant?
- microRNA combines with protein –> microRNA-protein complex
- binds to mRNA by complementary base pairing
- translation is prevented by stopping the ribosome attaching
- it is less specific than siRNA so works on more than 1 mRNA
what is the function of a tumour supressor gene?
what can a mutation in a tumour supressor gene lead to?
they MAKE PROTEINS which slow down rate of mitosis/speed up apoptosis (cell death)
- a non functional protein
(go through the whole lot - 1’,2’,3’)
the function of a proto-oncogene is to make?
what can a mutation to a proto-oncogene lead to what forming? what can happen next?
proto-oncogenes make proteins that increase the rate of mitosis
- an oncogene forms, oncogenes can be overexpressed
what does hypermethylation affect?
what is the result?
- affects tumour suppressor genes
- the proteins which slow down mitosis/ increase apoptosis are not transcribed
- so uncontrolled cell division occurs
what does hypomethylation affect?
what is the result?
(less methylation)
- affects proto-oncogenes
- so more proteins transcribed
- so uncontrolled cell division occurs
Explain how can oestrogen affect cell division? (5)
- oestrogen can bind to proteins forming transcription factor (oestrogen-oestrogen receptor complex)
- leads to increase in rate of cell division
- so increased DNA replication
- so increased mutation
- so greater possibility of cancer
