Lecture Notes

DNA Repair
Learning objectives:

1. Types of DNA repair
2. Molecular mechanisms involved in repairing DNA

DNA damage: how bad is it?

 Damage to DNA occurs continuously
 In humans approx. 500,000 modifications occur per cell per day
 It is minimised by several different DNA repair systems (>130 repair gene)

How does DNA damage occur?

 Endogenous Agents
- Formed inside the cell by normal metabolic pathways
 Exogenous Agents
- Come from the surrounding environment

,Consequence of DNA damage




DNA damage & repair mechanisms

 Which response/type of repair generally depends on the type/nature of the damage

, DNA repair mechanisms

 Direct reversal
 Excision repair (3 types)
 Recmbinatorial repair (2 types)
 Translation repair




Direct repair

 Direct repair mechanism are rare
 Involves the direct reversal or simple removal of the damage
 Repair of photodimers
 Repair of alkylated bases




Direct repair- photodimers