Mutations

Depurination

Loss of a purine base (adenine or guanine), leading to an apurinic site; can be repaired by base excision repair.

Deamination

Conversion of cytosine to uracil or adenine to hypoxanthine, causing mispairing; repaired by base excision repair.

Free Radicals/Oxidative Damage

Oxidative stress modifies bases, like turning guanine into 8-oxoguanine, which pairs incorrectly; can alter DNA and result in various mutations.

Ionizing Radiation

X-rays and gamma rays cause DNA strand breaks; repaired by non-homologous end-joining (NHEJ) or homologous recombination.

UV Light

Creates pyrimidine dimers, disrupting DNA structure; repaired by nucleotide excision repair.

Mutagens

Natural or artificial agents that induce mutations.

Base Analogs

Mimic normal bases but pair incorrectly; e.g., 5-bromouracil increases tautomeric shifts.

Alkylating Agents

Add alkyl groups to bases, causing mispairing or strand breaks; result in transition mutations.

Intercalating Agents

Insert between DNA bases, causing frameshifts and possible DNA unwinding; e.g., ethidium bromide.

Adduct-Forming Agents

Bind covalently to DNA, altering conformation and interfering with replication and repair to cause mutations.