DNA Repair and Cancer Flashcards
Name 2 sources that can damage DNA
- Ionising Radiation (CT/X-Ray)
- Mutagenic Chemicals
- Free Radicals
- Replication Errors
Name the 4 types of DNA damage
- Apurinic Site - Loss of a base
- Deamination - RNA base instead of DNA base
- Double Strand Break
- Intercalating Agent - Chemical between a base pair
What is DNA replication stress?
Inefficient replication that leads to the replication fork slowing, stalling or breaking
Name 4 ways DNA replication stress can occur
- Replication Machinery Defects
- Inefficient Replication
- Misincorporation
- Repetitive DNA leading to fork slippage
Which disease is caused by repetitive DNA resulting in neuron death?
Huntingdon’s Disease
Describe 3 ways DNA responds to damage
Apoptosis - Cell death
Senescence - Cell cycle arrest
Proliferation - DNA repair
Which type of DNA damage can be removed by exonuclease?
Misincorporation
What are the 3 DNA repair mechanisms?
- Base excision repair
- Nucleotide excision repair
- Mismatch repair
What are the two pathways of double strand break repair and which is most favourable?
Non-Homologous End Joining - 2 half chromosomes join using enzyme
Homologous Repair - Repair uses sequencing of a sister chromatid
- Joining 2 half chromosomes is likely to result in mutation
What is Carcinogenesis?
DNA replication stress causing mutations
What is Heterogeneity in terms of a tumour?
A tumour which contains different cell types and therefore promotes tumour evolution
Name 2 ways a tumour can become insensitive to chemotherapy
Differential Sensitivity - Tumour is made up of different cells, some of these are resistant to chemotherapy and continue to expand
Chemotherapy-Induced Mutagenesis - Chemicals that are given result in unfavourable mutation
Which cancer treatment is being developed using genetics?
Targeted inhibition of DNA damage repair pathways in cancer cells
E.G. PARP inhibitor in breast cancer
