Flashcards in DNA Repair Deck (22):
How is DNA damaged?
Exogenous- ionising radiation, alkylating agents, UV light, anti-cancer agents
Endogenous- DNA replication errors, V(D)J recombination, free radicals
What is the response to DNA damage in the body?
Cell cycle transition
What is the signalling cascade of DNA damage?
Where and what are cell cycle checkpoints?
After G1 before S
After G2 before mitosis
Temporary arrest (time for DNA damage to be repaired)
What is senescence?
Permanent cell cycle arrest
What is apoptosis?
What is the repair if there is a single strand break?
Base excision repair
What is the repair of there is a CPD?
Nucleotide excision repair
What repair occurs if there is a double strand break?
What repair occurs if there is insertion or deletion due to mismatch between AG?
What is a base excision repair?
DNA glucosylase removes incorrect nucleotide
AP endonuclease and deoxyribosephosphodiesterase allow space so correct nucleotide can be added using DNA polymerase and ligase
What is a mismatch repair?
Endonuclease and exonuclease is used to remove short strand of incorrect DNA
DNA polymerase and ligase then synthesise DNA again correctly
What is nucleotide excision repair?
Damaged area is cut
Repair is synthesised
How is a double strand break repaired?
Proteins recruited to protect ends
Proteins recruited to remove DNA damaged components
Ligase sticks the two broken ends back together
What is cancer?
Uncontrollable cell growth
What allows cancer to develop?
Suppression or alteration of DNA damage response
What syndromes are caused by mismatch repair?
Why is p53 important?
Mutated in many cancers
What can develop within a tumour?
What is a heterogenous tumour?
A tumour with sub-clones making it more difficult to treat as may be therapy resistance and lead to clonal expansion
What is the basis of cancer killing?
DNA damage e.g. Camptothecin