DNA Damage and Repair

A series of flashcards covering key vocabulary and concepts related to DNA damage and repair mechanisms.

Genotoxicants

Chemicals that damage DNA, causing genotoxicity.

Direct DNA Damage Types

Base damage and sugar-phosphate backbone damage.

8-hydroxyguanosine

An oxidized guanine caused by hydroxyl radicals or superoxide.

DNA Adduct

A chemical modification where a toxicant binds covalently to DNA bases.

Most Susceptible Base to Adduct Formation

Guanine.

Bay Region in PAHs

Necessary structure for adduct formation that forms a diol epoxide.

Types of Crosslinking in DNA Damage

Intrastrand, interstrand, and DNA-protein crosslinks.

Consequences of DNA Damage in a Cell

Apoptosis, mutations, cell cycle delay, and telomere shortening.

Enzyme that Adds Nucleotides to Telomeres

Telomerase.

Mutations from Misrepair of Double-Strand Breaks

Translocations, deletions, duplications, and inversions.

Difference between Apoptosis and Necrosis

Apoptosis is programmed cell death; necrosis is disordered cell death.

Types of Base Excision Repair (BER)

Short patch and long patch.

Key Feature of Nucleotide Excision Repair (NER)

Removes a long stretch (30-50 nucleotides) and repairs bulky adducts.

Proteins Involved in Transcription-Coupled NER

CSA and CSB.

Inhibitors of BER and NER

Arsenic, even without external DNA damage.

Common Source of Endogenous DNA Damage

Reactive oxygen species (ROS) and genotoxic steroid metabolites.

Organismal Impact of Unrepaired DNA Damage

Cancer, premature aging, birth defects, immunotoxicity, and infertility.

NHEJ vs. Homologous Recombination Repair

NHEJ joins broken DNA ends without a template, often causing deletions.

Error-Prone Polymerases

Replaced normal DNA polymerase when stalled at bulky adducts.

AP Sites in DNA

Locations where a base has been lost, often containing reactive aldehydes.