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DNA Mutations and Repair

DNA Mutations and Repair. Chapter 17. Mutation: is defined as an inherited change in genetic information by cell division or individual organisms. Chernobyl, April 26th, 1986. Mutations can be classified into categories. Categories of mutations. Somatic and germ line. Achondroplasia.

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DNA Mutations and Repair

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  1. DNA Mutations and Repair Chapter 17

  2. Mutation: is defined as an inherited change in genetic information by cell division or individual organisms. Chernobyl, April 26th, 1986

  3. Mutations can be classified into categories. Categories of mutations

  4. Somatic and germ line

  5. Achondroplasia Autosomal Dominant

  6. Gene Mutations can also be classified by type of mutation • 1. Base Substitutions □2. Insertions and deletions • 3. Frameshift mutations • 4. Expanding trinuleotide repeats Lead to

  7. Gene Mutations can also be classified by type of mutation • Base Substitutions Transitions and Transversions can be

  8. PURINE TO PYRIMIDINEPYRIMIDINE TO PURINE PURINE TO PURINE

  9. Expanding trinucleotide repeats

  10. Fragile X Syndrome Pre-mutation

  11. Fragile X syndrome:FMR-1 gene

  12. Strand slippage may cause repeats

  13. Phenotypic changes and mutations

  14. Reverse mutation Forward mutation

  15. Forward versus Reverse Mutations

  16. Terms associated with PHENOTYPIC effects of mutations on protein structure

  17. Phenotypic effects can also change function Gain of Gene Function1 Loss of Gene Function2 1 Sullivan, J.P. et al., Department of Pathology, College of Veterinary Medicine, 1998 The University of Georgia, Athens, GA or Qualtek Molecularlabs Web Site

  18. Loss of Function can also occur! Typically recessive mutations!

  19. Suppressor Mutations is a genetic change that hides the effect of another mutation

  20. Intragenic Suppressor Mutations

  21. Intergenic Mutation

  22. Lethal Mutations

  23. Do you remember something about each type of mutation?

  24. This is easy!

  25. Mutation Rates and Frequency 1 to 10 mutations per million gametes Incidence within a group

  26. Causes of Mutations Spontaneous Induced

  27. Environmentally Induced DNA changes

  28. Intercalating agents • Insert and distort DNA

  29. Radiation (Techa River) Hiroshima (Aug. 6th, 1945)

  30. Thymine Dimers SOS

  31. Chemicals and Reactions Leading to Mutations

  32. alklyating Deamination Adds OH

  33. Oxidative radicals • Reactive forms of oxygen can lead to these radicals

  34. Detecting mutations with the AMES test

  35. THE AMES TEST Salmonella typimurium

  36. AMES TEST • Saccharin • Aflatoxin 2-aminofluorene

  37. Aflatoxin B1

  38. DNA Repair: general characteristics • Double stranded DNA • Redundancy of pathways

  39. Types of DNA repair • Mismatch repair • Direct Repair • Base-Excision Repair • Nucleotide Excision Repair

  40. Mismatch repair • Mut H • Recognize GATC hemi-methylation • Mut S • Mut L

  41. A closer look at mismatch repair

  42. DIRECT REVERSAL REPAIR Direct Repair

  43. BASE EXCISION REPAIR

  44. BASE EXCISION REPAIR

  45. Nucleotide Excision Repair

  46. Diseases of DNA repair!

  47. Xeroderma pigmentosum Autosomal recessive

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