DNA repair - causes of damage Flashcards
During replication, DNA polymerase δ encounters a still unrepaired 3-meA (= an alkylated adenine)
TLS – Translesion synthesis
The chemotherapeutic drug cisplatin can crosslink DNA by binding to guanines. This happens not only in tumour cells but also in haematopoietic cells in the healthy bone marrow when exposed to the drug
HRR - homologous recombination repair
DNA polymerase ε erroneously synthesises a DNA strand with a deoxyadenosine opposite to a deoxycytidine
MMR – Mismatch repair
Hydrolytic damage in a neuron results in a depurination event creating an apurinic site in the DNA
BER – Base excision repair
Polonium is highly toxic due strong ionising effects of alpha particles. As a result, DNA double strand breaks can be induced in exposed permanent cells (e.g. brain tissue)
NHEJ – Non‑homologous end joining
The heterocyclic amine PhIP is a by-product of cooking meat and fish. During metabolic activation, an electrophilic intermediate is created that binds to guanine at C-8 position
NER – Nucleotide excision repair
Temozolomide, a chemotherapeutic drug, acts via alkylation of guanine at the O6 position creating O6-meG
DR – Direct repair