3.8.2 Gene Expression is controlled by a number of features. Flashcards
1
Q
How do alterations to tumour
suppressor genes lead to
cancer. (4)
A
- Increased methylation (of tumour suppressor genes);
- Mutation (in tumour suppressor genes);
- Tumour suppressor genes are not transcribed/expressed/mRNA not produced OR Amino acid sequenceor
different amino acid/primary or tertiary structure altered; - (Results in) rapid/uncontrollable cell division/cell division not regulated;
2
Q
What is a Transcription Factor? (3)
A
- (Protein/molecule) that moves from cytoplasm to DNA;
- (TF) binds to specific gene/genes/ to specific part of/site on DNA/ binds to promoter/RNA polymerase;
- Leads to/blocks (pre)mRNA production / allows/blocks binding of RNA polymerase
3
Q
How does oestrogen stimulate
Transcription? (6)
A
- Oestrogen diffuses through the cell membrane;
- attaches to receptor;
- receptor changes shape;
- receptor leaves protein complex which inhibited its action;
- oestrogen receptor binds to promoter region;
- enables RNA polymerase to transcribe target gene
4
Q
Describe RNA Interference. (3)
A
- MicroRNA/siRNA binds to cell’s mRNA by specific base pairing;
- (So) prevents mRNA being read by ribosomes;
- prevents translation/production of proteins
5
Q
Define Epigenetics. (2)
A
- Heritable changes in gene function;
- Without changes to the base sequence of DNA;
6
Q
Describe how methylation
leads to cancer. (3)
A
- Methyl groups (could be) added to (both copies of) a tumour suppressor gene;
- The transcription of tumour suppressor genes is inhibited;
- Leading to uncontrolled cell division/mitosis;