Mutagens and repair mechanisms Flashcards
Some common terminology The role of DNA replication in the fixation of mutations The relationship between mutagens and DNA damage Example mechanisms for DNA repair and mutation avoidance direct repair excision repair
What is DNA damage?
Chemical alteration of the DNA
What is DNA repair?
The removal of damage from DNA
What are the 2 generations of mutations?
Spontaneous: replication errors
Induced: mutagens, lesions and DNA damage
How does a replication error occur and what does it produce? (4)
A mistake is made
Polymerase doesn’t recognise
Cell doesn’t recognise
Mutation occurs
What is the definition of a mutagen?
Mutagens are chemical or physical agents that cause damage (allusion) to the eugenic material
What is the definition of a lesion?
A lesion is an alteration to the chemical structure of one of the components of DNA
what are the causes of physical mutagens? (4)
Heat
Acid
Radiation
UV light
What are the causes of chemical mutagens? (6)
Oxygen radicals Aflatoxin Benzopyrene Mustard gas Mitomycin C Psoralen
What are the 3 categories of single stranded DNA damage?
Adduct
Nick (short gap)
Mismatch
What are the 3 categories of double stranded DNA damage?
Replicated adduct
Chromosome break
Cross-link (most serious type)
What are the 2 types of cell repair of DNA damage?
- Direct repair (1)
2. DNA excision repair (2)
What is the definition of direct repair 1 and an example?
A reversal of the chemical reaction causing the lesion
Methyltransferase
What is a mechanism of mispairing O6-methylguanine: (3)
- Methyl-methane-sulphonate + DNA –> O and N alkylated products
- O6-methyl guanine - replication
- O6-methylguanine nucleotide + methyltransferase __> guanine nucleotide
What is the definition of DNA excision repair 2?
Removal and resynthesis of a damaged DNA section
