The Process of Restoring DNA After Damage. Genomes Are Subject to Damage by Chemical and Physical Agents in the Environment (e.g. Uv and Ionizing Radiations Chemical Mutagens Fungal and Bacterial Toxins Etc.) and by Free Radicals or Alkylating Agents Endogenously Generated in Metabolism. DNA Is Also Damaged Because of Errors During Its Replication. a Variety of Different DNA Repair Pathways Have Been Reported That Include Direct Reversal Base Excision Repair Nucleotide Excision Repair Photoreactivation Bypass Double Strand Break Repair Pathway and Mismatch Repair Pathway.
In Base Excision Repair an Altered Base Is Removed by a DNA Glycosylase Enzyme Followed by Excision of the Resulting Sugar Phosphate. the Small Gap Left in the DNA Helix Is Filled in by the Sequential Action of DNA Polymerase and DNA Ligase.
Any Process That Results in a Change in State or Activity of a Cell (in Terms of Movement Secretion Enzyme Production Gene Expression Etc.) As a Result of a Stimulus Indicating Damage to Its DNA From Environmental Insults or Errors During Metabolism.
The Chemical Reactions and Pathways Including Anabolism and Catabolism by Which Living Organisms Transform Chemical Substances. Metabolic Processes Typically Transform Small Molecules But Also Include Macromolecular Processes Such As DNA Repair and Replication and Protein Synthesis and Degradation.
Catalysis of the Cleavage of the N C1' Glycosidic Bond Between the Damaged DNA Base and the Deoxyribose Sugar Releasing a Free Base and Leaving an Apyrimidinic (ap) Site. Enzymes with This Activity Recognize and Remove Uracil Bases in DNA That Result From the Deamination of Cytosine or the Misincorporation of Dutp Opposite an Adenine.