DNArepair的研究方法.PDF

Research Methodology of Biotechnology DNA repair的研究方法 8/26 10:10-12:00 1 How can DNA become damaged? • Mismatched bases – Polymerase error rate about 1 in 104 (see later lectures) – Deamination of C to U leading to mismatch • Missing bases. Hydrolysis of purine-deoxyribose bond leading to AP-site. • Structural damage. Dimer formation. • Broken phosphodiester bonds. Chemicals/radiation • REPAIR MECHANISMS NECESSARY FOR SURVIVAL. 2 1 Sources of mutation • Natural polymerase error • Endogenous DNA damage oxidative damage depurination • Exogenous DNA damage radiation chemical adducts • “Error-prone” DNA repair 3 DNA的突變與修復 • DNA methylation – Can also lead to mutations • DNA repair – Types of DNA damage – Types of repair • Direct repair • Nucleotide excision repair • base excision repair • Postreplication repair • Mismatch repair 4 2 突變由數種DNA鹼基序列改變所產生 • 一個鹼基對置換(substitution) •鹼基刪除 (deletion):一或多對鹼基被刪除 •嵌入 (insertion):一或多對的鹼基嵌入DNA一股中 5 一個鹼基對置換(transition) • 一個鹼基置換另一個是最常見的突變型式。有兩種可能的 型式。 –同類置換 (transition)其為將一個嘌呤以另一種嘌呤置 換或一種嘧啶被另一種嘧啶取代 。 – 相反地 異類置換 (transversion)則以嘧啶置換嘌呤，或 以嘌呤置換嘧啶。 A T T A A T T A G C C G C G G C 同類置換(transition) 異類置換(transversion)