Class Notes

DNA Repair and Recombination

Dr. H. Flores-Rozas, Medical College of Georgia
Biochemistry, Lecture 23
November 1st, 2005

  1. Why is DNA Repaired?
  2. Common Types of DNA Damage and Spontaneous Alterations
  3. DNA Damage, Repair, and Consequences
  4. Common Features of Excision-Type Repair Pathways
  5. DNA Recombination
  6. Repair of DSBs by Non-Homologous End Joining (NHEJ)
  7. Translesion Synthesis
  8. Know

Why is DNA Repaired?

Common Types of DNA Damage and Spontaneous Alterations

DNA Damage, Repair, and Consequences

Cellular Response to DNA Damage

DNA Repair Pathologies

Reversal of Damage

Photoreactivation

Aberrant Methylation

Common Features of Excision-Type Repair Pathways

Base-Excision Repair (BER)

  1. DNA glycosylase recognizes the damaged base and removes it, generating an AP (apurinic, apyramidinic) site.
  2. AP endonuclease cleaves the phosphodiester bond, generating a single-strand break with a 5'-terminal deoxyribophosphate moiety.
  3. The 5'-deoxyribophosphate is excised by action of a DNA phosphodiesterase.
  4. The resulting single-nucleotide gap is repaired by DNA polymerase β (beta).
  5. The resulting nick is sealed by DNA ligase.

Nucleotide-Excision Repair (NER)

Mammalian NER Pathways

DNA Mismatch Repair (MMR)

DNA Recombination

Types of Homologous Recombination

Holliday Model for Homologous Recombination

Szostak Model for Recombination

Differences Between the Two Models

Factors Involved in Each Recombination Step

Repair of DSBs by Non-Homologous End Joining (NHEJ)

Translesion Synthesis

Mutagenic Repair of DSBs

Know

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