gene organisation, transcription and regulation

Question 1

define gene promoter

Answer 1

DNA sequence where initiation complex is assembled; contains transcription factor binding site and TATA initiation point for RNA pol II

Question 2

gene promoter diagram

Answer 2

diagram from NAGE 3

Question 3

define transcription factor

Answer 3

DNA binding proteins which bind to promoter to regulate primary level of gene transcription; activate/repress expression leading to specialisation

Question 4

effect of aspirin on IkB transcription factor

Answer 4

IkB inhibits increasing circulating cytokines; aspirin enhances this inhibition by preventing breakdown of IkB prior to transcription; therefore NFkB (which increases circulating cytokines) is unable to enter the cell’s nucleus, meaning transcription doesn’t occur

Question 5

oestrogen receptor as a transcription factor in breast cancer

Answer 5

interacts with steroid for the transcription of oestrogen regulated genes; anti-oestrogen tamoxifen reduces transcription and is used as a treatment

Question 6

define basal transcription complex

Answer 6

allows RNA pol II to be phosphorylated and transcribe RNA; if no other transcription factors bind, it is low level transcription

Question 7

basal transcription complex: TF IID binding

Answer 7

TF IID contains TBP (TATA binding protein) and TAFs (TATA binding associated factors); binds to TATA; partially unwinds DNA helix, widening minor groove; bases contact with DNA; asymmetric so unidirectional

Question 8

basal transcription complex: other transcription factors binding

Answer 8

other TFs bind, then RNA pol II binds (to TF IIB); other TFs then bind and phosphorylate enzyme to activate it or promote further unwinding

Question 9

transcription factor activity

Answer 9

cell lineage, remodel chromatin

Question 10

chromatin: hyperacetylation

Answer 10

stimilates expression; acetylated histones are open; increases transcription

Question 11

chromatin: hypoacetylation

Answer 11

stimulates repression; histones are closed; decreases transcription

Question 12

altering trancription factor activity

Answer 12

altered by cell signalling, heat, light etc. to become mutated/abnormal; inhibited by drugs e.g. aspirin