Mutagens and repair mechanisms Flashcards
What is the definition of a mutagen?
A chemical or physical agent that causes a lesion (damage) to the genetic material
What is the DNA damage?
Chemical alteration of the DNA
What is DNA repair?
The removal of damage from DNA
How are mutations produced?
1) Spontaneous: -replication errors
2) Induced - Mutagens, Lesions and DNA damage
3) DNA damage is unavoidable
4) Categorising DNA Damage
What is the definition of a lesion?
An alteration to the chemical structure of one of the components of DNA
What are the categories of DNA damage?
Single strand:
- adduct
- nick (short gap)
- mismatch
Double strand:
- replicated adduct
- chromosome break
- cross-link
How do cells repair DNA damage?
- Direct Repair
- DNA excision repair
These aren’t the only mechanisms there are several others
What is direct repair?
A reversal of the chemical reaction causing a lesion
-eg, methyltransferase (methylating agents react with DNA to produce methyl-guanine, methyltransferase removes the methyl group to form guanine nucleotide)
What is DNA excision repair?
Removal and resynthesis of a damaged DNA section
eg. UvrABCD system in bacteria
