mutations, gene expressions and cancer Flashcards
what is the promotor region
one or more base sequences found upstream of a gene that control the expression of a gene
What is a transcription factor ?
Proteins which, when activated, bind to the promoter region of a gene stimulating RNA polymerase to begin transcription of that target gene
Define epigenetics
heritable phenotypes changes that do not involve alterations in the DNA base sequence
Explain what is meant by the terms totipotent and pluripotent.
- totipotent cells can give rise to a complete human/all cell types;
- pluripotent can only give some cell types;
Explain how cells produced from stem cells can have the same genes yet be of different types.
- {not all / different} genes are switched {on / off} /active / activated ;
- correct and appropriate reference to factors /mechanisms for gene switching ;
- e.g. reference to promoters / transcription factors
Describe the mechanism by which a signal protein causes the synthesis of mRNA.
- signal protein {binds to / joins to / interacts with / activates}
- receptor on surface membrane;
- messenger molecule moves from cytoplasm and enters nucleus;
- {produces / activates} transcription factor;
- binds to promoter region;
- RNA polymerase transcribes target gene;
Explain how oestrogen enables RNA polymerase to transcribe its target gene.
- Oestrogen diffuses through the cell membrane;
- attaches to ERα receptor;
- ERα receptor changes shape;
- ERα receptor leaves protein complex which inhibited it’s action;
- oestrogen receptor binds to promoter region;
- enables RNA polymerase to transcribe target gene
Explain how the methylation of tumour suppressor genes can lead to cancer.
- Methylation prevents transcription of gene;
- Protein not produced that prevents cell division / causes cell death / apoptosis;
- No control of mitosis.
Describe what is meant by a malignant tumour.
- mass of undifferentiated / unspecialised / totipotent cells;
- uncontrolled cell division;
- (not ‘repeated’)
- metastasis / (cells break off and) form new tumours /
- spread to other parts of body;
Describe how altered DNA may lead to cancer.
- (DNA altered by) mutation;
- (mutation) changes base sequence;
- of gene controlling cell growth / oncogene / that monitors cell division;
- of tumour suppressor gene;
- change protein structure / non-functional protein / protein not formed;
- (tumour suppressor genes) produce proteins that inhibit cell division;
- mitosis;
- uncontrolled / rapid / abnormal (cell division);
- malignant tumour;
Describe how alterations to tumour suppressor genes can lead to the development of tumours.
- (Increased) methylation (of tumour suppressor genes);
- Mutation (in tumour suppressor genes);
- Tumour suppressor genes are not transcribed / expressed OR Amino acid sequence / primary structure altered;
- (Results in) rapid/uncontrollable cell division;
explain why fragments of DNA from cancer cells may be present in blood plasma
- cancer cells break open
- release DNA
Name all types of mutation
- substitution
- addition
- deletion
- chromosomal (non-disjunction)
- inversion
- duplication
- translocation (non-homologous)
what do mutagenic agents increase
the rate of spontaneous mutation
name applications of stem cells to medical research
- producing tissues for skin grafts
- research into producing organs for transplant
- research how cells be specialised
- research into cancer and other serious diseases
