Mutations

1. Mutations

2. 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

3. Are Mutations Helpful or Harmful? Mutations happen regularly Almost all mutations are neutral Chemicals & UV radiation cause mutations Many mutations are repaired by enzymes

4. Are Mutations Helpful or Harmful? Some type of skin cancers and leukemia result from somatic mutations Some mutations may improve an organism’s survival (beneficial)

5. Types of Mutations

6. Chromosome Mutations May Involve: Changing thestructureof a chromosome Theloss orgainof part of a chromosome

7. Chromosome Mutations Five types exist: Deletion Inversion Translocation Nondisjunction Duplication

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

9. Chromosome Mutations • Cri-du-chat • Deletion of material on 5th chromosome • Characterized by the cat-like cry made by cri-du-chat babies • Varied levels of metal handicaps

10. Inversion Chromosome segment breaks off Segment flips around backwards Segment reattaches

11. Duplication Occurs when a gene sequence is repeated

12. Translocation Involves two chromosomesthat aren’t homologous Part of one chromosome is transferred to another chromosomes

13. Translocation

14. Nondisjunction • Failure of chromosomes to separate during meiosis • Causes gamete to have too manyortoo fewchromosomes • Disorders: • DownSyndrome – three 21st chromosomes • Turner Syndrome – single X chromosome • Klinefelter’s Syndrome – XXY chromosomes

17. Chromosome Mutation Animation

18. Gene Mutations Change in the nucleotide sequenceof a gene May only involve a single nucleotide May be due to copying errors, chemicals, viruses, etc.

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

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

21. Point Mutation Sickle Cell diseaseis the result of one nucleotide substitution Occurs in the hemoglobin gene

22. Frameshift Mutation Inserting or deletingone or more nucleotides Changes the “reading frame” like changing a sentence Proteins built incorrectly

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

24. Amino Acid Sequence Changed

25. Gene Mutation Animation

26. HOX GENES • A series of genes that control the differentiation of cells and tissues in the embryo. • Hox genes determine an animal’s basic body plan

28. POLYDACTYLE

29. FYI

30. Normal Male 2n = 46 30

31. Normal Female 2n = 46 31

32. Male, Trisomy 21 (Down’s) 2n = 47 32

33. Female Down’s Syndrome 2n = 47 33

34. Female with Down’s Syndrome

35. Klinefelter’s Syndrome 2n = 47 35

36. Sex Chromosome Abnormalities • Klinefelter’s Syndrome • XXY, XXYY, XXXY • Male • Sterility • Small testicles • Breast enlargement

37. XYY SYNDROME

38. Sex Chromosome Abnormalities • XYY Syndrome • Normal male traits • Often tall and thin • Associated with antisocial and behavioral problems

39. Turner’s Syndrome 2n = 45 39

40. Sex Chromosome Mutations • Turner’s Syndrome • X0 • Female • sex organs don't mature at adolescence • sterility • short stature • sterility • short stature

41. Sex Chromosome Mutations • XXX • Trisomy X • Female • Little or no visible differences • tall stature • learning disabilities • limited fertility