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Maintenance of genomes
• Replication errors
Inserting a wrong nucleotidecausing a mismatch
Inserting or deleting nucleotidescausing helix distortion
Maintenance of genomes
• Replication errors
Inserting a wrong nucleotidecausing a mismatch
Inserting or deleting nucleotidescausing helix distortion
Maintenance of genomes
• DNA damage
Physical damage – radiation, heat
Hydrolytic damage
Chemical damage – base modifications, base analogs, intercalating agents
Figure 16.9 Genomes 3 (© Garland Science 2007)
Cyclobutyl dimers and formation of a (6-4) photoproduct caused by UV light
(results in a deletion)
In some organisms photolyases repair crosslinks
In humans the damaged region is excised and re-synthesized
Maintenance of genomes
• DNA damage
Physical damage – radiation, heat
Hydrolytic damage
Chemical damage – base modifications, base analogs, intercalating agents
Maintenance of genomes
• DNA damage
Physical damage – radiation, heat
Hydrolytic damage
Chemical damage – base modifications, base analogs, intercalating agents
Double-strand break repair(Non-homologous endjoining)
Double-strand breaks arecaused by ionizing radiation
Replication-linked repair
SOS repair in E. coli
Expression of Pol IV and Pol V isinduced by DNA damage.