Understanding DNA Mutations: Types and Effects

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)

6. Chemicals & UV radiation cause mutations – skin cancer

8. Many mutations are repaired by enzymes

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

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

11. Types of Mutations • Chromosomal • Gene

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

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

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

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

18. Duplication • Occurs when a gene sequence is repeated

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

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

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

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

26. Normal Female Karyotype 2n = 46

27. 2n = 46 Normal Male Karyotype

28. Female Down’s Syndrome 2n = 47

29. 2n = 47 Male, Trisomy 21 (Down’s)

32. 2n = 45 Turner’s Syndrome

33. 2n = 47 Klinefelter’s Syndrome

34. 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

36. 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.

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

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

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

40. Deletion

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

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

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

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

50. Gene Mutation Animation