《分子生物学》课程教学课件（PPT讲稿）Chapter 4 DNA Damage and Repair

Moleculaogy Course CHAPTER 4:DNA damage and repair(DNA损伤与修复) Help l!my DNA is broken teaching hours 2025/5/15

2025/5/15 2 CHAPTER 4: DNA damage and repair（DNA损伤与修复） •Molecular Biology Course 4 teaching hours

Outline: Section 1:The types and causes of DNA damage(DNA损伤的类型及原因) Section 2:The repair mechanisms of DNA damage(DNA损伤的修复机制) 2025/5/15 3

2025/5/15 3 Outline: Section 1：The types and causes of DNA damage (DNA损伤的类型及原因) Section 2: The repair mechanisms of DNA damage (DNA损伤的修复机制)

■Key points(重点掌握)： The types and causes of DNA damage (DNA损伤的类型及原因) The repair mechanisms of DNA damage (DNA损伤的修复机制) 2025/5/15 4

2025/5/15 4 ◼ Key points (重点掌握)： The types and causes of DNA damage (DNA损伤的类型及原因) The repair mechanisms of DNA damage (DNA损伤的修复机制)

The consequence of high rates of mutation Mutation in germ cell(生殖细胞)would destroy the species ■Mutation in somatic cell(体细胞)would destroy the individual. Maintenance of the correctness of the DNA sequence is definitely crucial for living organisms. 2025/5/15 5

2025/5/15 5 The consequence of high rates of mutation ◼ Mutation in germ cell (生殖细胞) would destroy the species ◼ Mutation in somatic cell (体细胞) would destroy the individual. Maintenance of the correctness of the DNA sequence is definitely crucial for living organisms

Two important sources for mutation (unavoidable) Inaccuracy in DNA replication-Errors (错误) ■ Chemical and radiant damage to the genetic material(environment) 2025/5/15 6

2025/5/15 6 Two important sources for mutation (unavoidable) ◼ Inaccuracy in DNA replication- Errors (错误) ◼ Chemical and radiant damage to the genetic material (environment)

To repair an error or damage First,Detect the errors or damage Second,Mend/repair the errors or lesions in a way to restore the original DNA sequence. 2025/5/15 7

2025/5/15 7 To repair an error or damage First, Detect the errors or damage Second, Mend/repair the errors or lesions in a way to restore the original DNA sequence

Questions to be addressed 1.How is the DNA mended rapidly enough to prevent errors from becoming set in the genetic material as mutation 2.How does the cell distinguish the parental strand from the daughter strand in repairing replication errors 2025/5/15

2025/5/15 8 Questions to be addressed 1. How is the DNA mended rapidly enough to prevent errors from becoming set in the genetic material as mutation 2. How does the cell distinguish the parental strand from the daughter strand in repairing replication errors

3.How does the cell restore the proper DNA sequence when the original sequence can no longer be read? 4.How does the cell deal with lesions that block replication? 2025/5/15 9

2025/5/15 9 3. How does the cell restore the proper DNA sequence when the original sequence can no longer be read? 4. How does the cell deal with lesions that block replication?

Section 1: The types and causes of DNA damage 2025/5/15 10

2025/5/15 10 Section 1: The types and causes of DNA damage

1.1 DNA undergoes damage spontaneously (自发的)from hydrolysis(水解)and deamination(脱氨基) Resulted from the action of water 2025/5/15 11

2025/5/15 11 1.1 DNA undergoes damage spontaneously (自发的) from hydrolysis (水解) and deamination (脱氨基) Resulted from the action of water