Understanding Mutations: Types, Effects & Chromosomal Abnormalities

1. MUTATIONS

2. DNA TACGCACATTTACGTACG aa aa aa aa aa aa aa mRNA AUGCGUGUAAAUGCAUGC protein trait Mutations • Changes to DNA are called mutations • change the DNA • changes the mRNA • may change protein • may change trait

3. What Causes Mutations? • There are two ways in which DNA can become mutated: • Mutations can be inherited. • Parent to child • Mutations can be acquired. • Environmental damage • Mistakes when DNA is copied

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

5. 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)

6. Types of Chromosomal Mutations

7. Chromosome Mutations • May Involve: • Changing the structure of a chromosome • Changing the number

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

9. Deletion • Due to breakage • A piece of a chromosome is lost ABCD-EFGH ABCD-EF

10. Inversion • Chromosome segment breaks off • Segment flips around backwards • Segment reattaches ABCD-EFGH ABDC-EFGH

11. Duplication • Occurs when a gene sequence is repeated ABCD-EFGH ABCDBCD-EFGH

12. Translocation • Involves two chromosomes that aren’t homologous • Part of one chromosome is transferred to another chromosomes ABCD-EFGH WXY-Z  ABCD-EF WXY-ZGH

13. Translocation

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

16. Chromosome Mutation Animation

17. Chromosome Mutations • Down Syndrome • Chromosome 21 does not separate correctly. Trisomy 21 • They have 47 chromosomes in stead of 46. • Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of intelligence. • Similar facial features

18. 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 mental handicaps

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

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

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

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

23. KARYOTYPE ANALYSIS

24. Karyotype Pictures of paired human chromosomes arranged by size, used to identify abnormalities in fetuses Cells from an amniotic fluid sample are cultured, stained & photographed

26. 1) Autosomes all the chromosomes except the sex chromosomes (in humans, there are 22 pair) 2) Sex chromosomes The sex-determining chromosomes, the X & Y

28. Normal Male 2n = 46

29. Normal Female 2n = 46

30. Male, Trisomy 21 (Down’s) 2n = 47

31. Female Down’s Syndrome 2n = 47

32. Klinefelter’s Syndrome 2n = 47

33. Turner’s Syndrome 2n = 45