DNA damage and repair mechanism
Download as PPT, PDF17 likes9,268 views
The document discusses the structure, damage, and repair mechanisms of DNA, outlining its significance as the genetic material in various organisms. It details types of DNA damage, such as single base changes and structural changes, and illustrates their causes and effects. Furthermore, it describes DNA repair mechanisms like mismatch repair, nucleotide-excision repair, and base-excision repair as essential systems to correct DNA injuries.
More Related Content
Similar to DNA damage and repair mechanism (20)
DNA damage and repair mechanism
- 1. Submitted To: Submitted By: SOS in Biotechnology Deepti Maheshwari JIWAJI UNIVERSITY DNA DAMAGEDNA DAMAGE ANDAND REPAIR MECHANISMREPAIR MECHANISM
- 2. CONTENTS: Introduction Structure of DNA DNA Damage DNA Repair
- 3. INTRODUCTION DNA makes up the genetic material in prokaryotes, eukaryotes and some viruses also. It is the ultimate source of biological information. The shapes and activities of individual cells are, to a large extent, determined by genetic instructions contained in DNA. They carry the information in the form that can be passed from one generation to another.
- 5. It is an event that introduces a deviation from the usual double-helical structure of DNA. DNA DAMAGE: Single Base Changes Structural Changes DNA damage can lead to : •Conversion of one base to another •Affect the DNA sequence. •Does not interferes with the process of replication or transcription and translation •E.g.(a) Deamination of cytosine to uracil (b) Insertion of adenine in place of cytosine. •Change in the structure of DNA occurs. •Physical impediment to the process of replication or transcription. E.g.(a) Formation of thymine dimers. (b) Methylation of a base.
- 6. FIG: (A ) Mismatched base pairing between U and G FIG: (B ) Mismatched base pairing between A and G Cause : NITROUS ACID, causes oxidative deamination of the amino groups in cytosine. Cause: REPLICATION ERROR which inserts adenine in place of cytosine. EXAMPLES OF SINGLE BASE CHANGES IN DNA:
- 7. EXAMPLES OF STRUCTURAL CHANGES IN DNA: FIG: (A ) Dimer formation between adjacent thymine dimers FIG: (B) Addition of methyl group to guanine Cause :UV IRRADIATION causes dimers which blocks the replication process. Cause : ALKALYTING AGENTS causes methylation of guanine.
- 8. DNA REPAIR: Injury to DNA is minimized by DNA repair systems that recognize and correct the damage. In Escherichia coli , following type of DNA repair mechanisms exist: 1.) Mismatch repair mechanism 2.) Nucleotide-excision repair mechanism 3.) Base-excision repair mechanism
- 9. 1.) Mismatch repair mechanism: Fig: Early steps of methyl-directed mismatch repair.
- 10. Fig: Completing methyl-directed mismatch repair. 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’
- 11. 2.) Nucleotide-excision repair mechanism:
- 13. 3.) Base-excision repair mechanism:
- 15. REFRENCES: GENES VII by Benjamin Lewin (page no. 447-453) Principles Of Biochemistry (4th edition) by David L. Nelson and Michael M. Cox (page no. 966-975) Principles Of Genetics (6th edition) by D. Peter Snustad and Michael J. Simmons (page no. 347-350)