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DNA Mutations

DNA Mutations. What Are Mutations?. Changes in the nucleotide sequence of DNA. May occur in somatic cells & aren’t passed to offspring May occur in gametes (eggs & sperm) and be passed to offspring. Mutations happen regularly (its very common)

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DNA Mutations

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  1. DNAMutations

  2. What Are Mutations? Changes in the nucleotide sequence of DNA

  3. May occur in somatic cells & aren’t passed to offspring • May occur in gametes (eggs & sperm) and be passed to offspring

  4. Mutations happen regularly (its very common) • Almost all mutations are neutral (doesn’t harm organism)

  5. Chemicals & UV radiation cause mutations – skin cancer

  6. Many mutations are repaired by enzymes

  7. Some type of skin cancers and leukemia result from somatic mutations • Can you “catch” cancer from someone? NO!

  8. Some mutations may improve an organism’s survival (beneficial)

  9. Types of Mutations • Chromosomal • Gene

  10. Chromosomal Mutations • May Involve: • Changing the structureof a chromosome • Theloss or gainof part of a chromosome

  11. Chromosomal Mutations • Five types exist: • Deletion • Inversion • Duplication • Translocation • Nondisjunction

  12. Deletion • Due to breakage • A piece of a chromosome is lost

  13. Inversion • Chromosome segment breaks off • Segment flips around backwards andreattaches

  14. Duplication • Occurs when a gene sequence is repeated

  15. Translocation • Involves two chromosomes that aren’t homologous (similar) • Part of one chromosome is transferred to another chromosomes

  16. Nondisjunction • Failure of chromosomes to separate during meiosis (making of sperm or egg) • Causes gamete to have too many or too few chromosomes

  17. Chromosome Mutation Animation http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter11/animation_quiz_4.html

  18. Disorders caused by nondisjunction: • DownSyndrome • Turner Syndrome • Klinefelter’s Syndrome

  19. Normal Female Karyotype 2n = 46

  20. 2n = 46 Normal Male Karyotype

  21. Female Down’s Syndrome 2n = 47

  22. 2n = 47 Male, Trisomy 21 (Down’s)

  23. 2n = 45 Turner’s Syndrome

  24. 2n = 47 Klinefelter’s Syndrome

  25. http://www.dailymail.co.uk/health/article-1082293/The-XYY-Factor-How-rare-chromosome-disorder-brought-son-world-pain.htmlhttp://www.dailymail.co.uk/health/article-1082293/The-XYY-Factor-How-rare-chromosome-disorder-brought-son-world-pain.html

  26. Gene Mutations • Change in the nucleotide sequence of a gene • May only involve a single nucleotide • May be due to copying errors, chemicals, viruses, etc.

  27. Types of Gene Mutations • Include: • Point Mutations • Substitutions • Insertions • Deletions • Frameshift Mutations

  28. Point Mutation • Change of a single nucleotide • Includes the deletion, insertion, or substitution of ONE nucleotide in a gene

  29. Point Mutation • Sickle Cell disease is the result of one nucleotide substitution • Occurs in the hemoglobin gene

  30. Deletion

  31. Substitution • a single nucleotide is substituted with (or exchanged for) a different nucleotide that may result in an altered sequence of amino acid

  32. Insertion • Nucleotides are inserted into sequence altering codon pattern

  33. Frameshift Mutation • Inserting or deleting one or more nucleotides • Changes the “reading frame” like changing a sentence • Proteins built incorrectly

  34. Frameshift Mutation • Original: • The fat cat ate the wee rat. • Frame Shift (“a” added): • The fat caa tet hew eer at.

  35. Gene Mutation Animation

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