DNA repair mechanism
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Transcript of DNA repair mechanism
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DNA REPAIR MECHANISM
BHARATESHA.S 7TH SEM 2014-15GUIDED BY:
CHANDRAKANTH.RMOLECULAR BIOLOGY DEPT.
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CONTENTS
• Introduction• Mismatch repair• Base excision repair• Nucleotide excision repair • Transcription coupled DNA repair • Double Strand Break repair• Photo reactivation • Conclusion• References• Acknowledgement
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INTRODUCTION
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Mismatch repair removes errors that escape proofreading
★Increase the accuracy of DNA by an additional 2-3 orders of magnitude
★Two challenges: ● Scan the genome rapidly● Correct the mismatch accurately ( that is it must recognize the newly synthesized strand)
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MutS scans the DNA,recognizing the mismatch from the distortion they cause in the DNA backbone
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Base excision repair enzymes remove damaged bases by a base-flipping mechanism
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Nucleotide excision repair enzymes cleave damaged DNA on either side of the lesion
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Transcription coupled DNA repair Nucleotide excision repair system is capable of
rescuing RNA polymerase that has been arrested by the presence of lesions in the DNA template
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Double Strand Break repair model for homologous recombination
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Photo reactivation (the enzyme DNA photolyase captures energy from light )
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Conclusion
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REFERENCES
I. James D.Watson, (2013) Molecular biology of the gene 7th edition, Cold Spring Harbour Laboratory Press, New york- 313-324pp.
II. David L.Nelson, Michael M.Cox, (2011) Principles of Biochemistry 5th edition , W.H.Freeman and Company, New york- 993-999pp.
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ACKNOWLEDGEMENT
I would like to thank my guide Chandrakanth.R for his valuable guidance and our course coordinator Dr.N.S.Devaki madam for providing me this opportunity.
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THANK YOU