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12-4

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Mutations

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12-4

  1. 1. 12-4 Mutations
  2. 2. 12-4 Mutations• Changes in the genetic material• Kinds of mutation – Gene mutation • Changes in a single gene – Chromosomal mutation • Changes in whole chromosome
  3. 3. Gene mutation
  4. 4. Gene mutation• Types – Point mutation: changes in one nucleotide • Single base substitution • Single base insertion • Single base deletion – Frame shift mutation: changes in nucleotides leads to the shift of reading frame (grouping of the codons) • Insertion • Deletion
  5. 5. Normal gene Substitution GGTCACCTCACGCCA GGTCTCCTCACGCCA ↓ ↓ CCAGUGGAGUGCGGU CCAGAGGAGUGCGGU mRNA codons mRNA codons ↓ ↓ Pro-Arg-Glu-Cys-Gly Pro-Glu-Glu-Cys-Gly Amino acids Amino acids Deletion Insertion GGTGCTCCTCACGCCA GGTCCCTCACGCCA ↓ ↓ CCACGAGGAGUGCGGU CCAGGGAGUGCGGU ↓ ↓ Pro-Arg-Gly-Val-Arg Pro-Gly-Ser-Ala-Val
  6. 6. Chromosomal mutation 1.duplication Structure 2.inversion change 3.translocation 4.deletionChanges in Have one extra or onechromosomes aneuploidy less chromosome (2n+1,2n-1) Number Caused by change nondisjunction polyploidy Have three or more sets of each type of chromosome (3n, 4n)
  7. 7. Non-disjunction• Fails to separate chromosomes in meiosis 1 or 2• Gametes become n-1 or n+1 Normal X meiosis 2 l l Non-disjunction X in meiosis 2 ll XX Normal XX meiosis 2 ll ll back
  8. 8. Significance of mutation• Most are neutral• Some are harmful – Cause human genetic disorders – Cause some types of cancers• Some are beneficial – Polyploidy plants are larger and stronger – Mutations lead to evolution in living organisms
  9. 9. Example of Genetic disorder 1) Down syndrome • 47, trisomic 21
  10. 10. Example of Genetic disorder 2) Turner syndrome • 45 chromosome, xo
  11. 11. Example of Genetic disorder 3) Klinefelter syndrome – 47, XXY
  12. 12. Example of Genetic disorder 4) Jacob syndrome – 47, XYY back
  13. 13. Examples of polyploidy back
  14. 14. Examples of polyploid crops• Triploid crops(3n):apple, banana, citrus, ginger, watermelon• Tetraploid(4n) crops: apple, durum or macaroniwheat, cotton, potato, cabbage, leek, tobacco, peanut, kinnow, Pelargonium• Hexaploid crops(6n): chrysanthemum, breadwheat, triticale, oat, kiwifruit• Octaploid crops(8n): strawberry, dahlia, pansies, sugarcane, oca (Oxalis tuberosa)

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