DNA repair - causes of damage

Question 1

During replication, DNA polymerase δ encounters a still unrepaired 3-meA (= an alkylated adenine)

Answer 1

TLS – Translesion synthesis

Question 2

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

Answer 2

HRR - homologous recombination repair

Question 3

DNA polymerase ε erroneously synthesises a DNA strand with a deoxyadenosine opposite to a deoxycytidine

Answer 3

MMR – Mismatch repair

Question 4

Hydrolytic damage in a neuron results in a depurination event creating an apurinic site in the DNA

Answer 4

BER – Base excision repair

Question 5

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)

Answer 5

NHEJ – Non‑homologous end joining

Question 6

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

Answer 6

NER – Nucleotide excision repair

Question 7

Temozolomide, a chemotherapeutic drug, acts via alkylation of guanine at the O6 position creating O6-meG

Answer 7

DR – Direct repair