Gene stability and DNA repair

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Gene stability and DNA repair

  1. 1. Gene stability and DNA repair…<br />Presented by <br />Minakshisaikia<br />2nd semester, <br />23rdFebruary 2010<br />1<br />
  2. 2. “Mutation”<br />2<br />
  3. 3. Mutation…<br />Error in DNA replication.<br />Damaging effects of mutagens(chemicals and radiations).<br />CHEMICALS: Alkylating agents like nitrosoguanidine, nitrosamine, etc.<br />RADIATIONS: X-rays, U.V.rays, etc.<br />3<br />
  4. 4. 1.ERROR IN REPLICATION…<br />4<br />
  5. 5. 2.ONE POSSIBLE EFFECT OF MUTAGEN<br />5<br />
  6. 6. “DNA repair system”<br />6<br />
  7. 7. 7<br />
  8. 8. DNA repair in a nut shell…<br />8<br />
  9. 9. 1.PHOTOREACTIVATION /direct repair system…<br />As the name suggests it acts directly on damaged nucleotides, converting each one back to its original structure.<br />9<br />
  10. 10. Thymine dimerisation…<br />10<br />
  11. 11. 2.EXCISION REPAIR SYSTEM…<br />It involves excision of a segment of the polynucleotide containing a damaged site, followed by resynthesis of the correct nucleotide sequence by a DNA Polymerase.<br />11<br />
  12. 12. ‘Excision repair system’<br />12<br />
  13. 13. 3.MISMATCH REPAIR SYSTEM…<br /> It corrects errors of replication, again by excising a stretch of single-stranded DNA containing the offending nucleotide and then repairing the resulting gap.<br />13<br />
  14. 14. Methylation process…<br />14<br />
  15. 15. ‘mismatch repair system’<br />15<br />
  16. 16. 4.SOS REPAIR SYSTEM…<br />‘Save Our Souls’<br />The SOS repair system is an emergency measure for copying with a damaged genome.<br />This is error prone.<br />16<br />
  17. 17. ‘SOS repair system’<br />17<br />
  18. 18. Conclusion:<br />“A possible definition of mutation is therefore a deficiency in DNA repair…”<br />18<br />
  19. 19. Bibliography…<br />Genomes 3, T.A.Brown<br />Genes vii, Benjamin Lewin<br />Internet, Google Search<br />19<br />
  20. 20. Thankyou… for your patience!!!<br />20<br />

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