Medical Genetics

1. Medical Genetics Human Anatomy and Physiology II Oklahoma City Community College Dennis Anderson

2. Produces daughter cells with 46 chromosomes Used in growth and repair Mitosis

3. Mitosis • DNA is duplicated • Doubled chromosomes form from duplicated DNA • Each cms has 2 identical chromatids Chromatid Chromatid

4. Mitosis Metaphase Chromosomes line up in a single row.

5. Chromosomes separate Each chromatid becomes a single chromosome

6. Reduce the chromosome number to half that of body cells Produce gametes Egg Sperm Meiosis

7. Meiosis Metaphase Chromosomes line up in a double row.

8. Chromosomes separate Each each daughter cell gets doubled chromosomes

9. Doubled Chromosomes Separate in Second Meiotic Division

10. Mitosis Metaphase Meiosis Metaphase

11. Cms 1 Cms 1 Cms 2 Cms 2 Double Filed Chromosomes • Daughter cells receive ONE of each cms pair • Daughter cells receive ONE allele for most traits • New combinations of alleles possible

12. Gene • A unit of heredity that controls the development of one trait • Made of DNA

13. Allele • Member of a paired gene • One allele comes from each parent • Represented by a single letter

14. Examples of Alleles Dwarfism = D Normal height = d DD = Dwarfism Dd = Dwarfism dd = Normal height Dwarf Band

15. Dominant & Recessive Alleles • Dominant alleles are expressed • Recessive alleles are not expressed in the presence of a dominant allele • Recessive alleles are only expressed if both recessive alleles are present

16. Homozygous • Both alleles alike • AA or aa

17. Heterozygous • Alleles are different • Aa

18. Genotype • Genetic make up • Represented by alleles • DD & Dd are genotypes for dwarfism

19. Phenotype • A trait • Genotype determines the phenotype • Dwarfism is a phenotype

20. Codominant • Two different alleles are both dominant • A = allele for type A blood • B = allele for type B blood • AB = results in type AB blood

21. Karyotype • Picture of chromosomes from an individual

22. Homologous Chromosomes • Chromosomes of the same pair • Karyotypes are usually arranged with homologous chromosomes paired together

23. Mutation • Change in a gene or chromosome • Causes an abnormal trait

24. Mutagen Cigarette smoke Pesticides X-rays Ulatraviolet light Nuclear radiation Agent that causes mutations

25. Homologous chromosomes line up in a double file in metaphase I of meiosis

26. Homologous Pairs Separate

27. Four Gametes With Single Chromosomes

28. Fertilization

29. Nondisjunction

30. Trisomy

31. Sex Chromosomes

32. Sex Chromosomes • Male have Xy • Male gametes have either X or y • Females have XX • Female gametes have X

33. Autosomes Chromosomes 1-22

34. X-Linked Traits • Alleles are on the X chromosome • Females have two alleles • Males have one allele • Only one X chromosome

35. Normal Male

36. Normal Female

37. Trisomy 21Down Syndrome

38. Down Syndrome • Large tongue • Flat face • Slanted eyes • Single crease across palm • Mental retardation • Some are not

39. Maternal Age & Down Syndrome

40. Trisomy 18Edward Syndrome

41. Edward Syndrome • Heart defects • Displaced liver • Low-set ears • Abnormal hands • Severe retardation • 98% abort • Lifespan < 1 year

42. Trisomy 13Patau Syndrome

43. Patau Syndrome • Cleft lip and palate • Extra fingers & toes • polydactylism • Defects • Heart • Brain • Kidneys • Most abort • Live span < 1 month

44. Klinefelter Syndrome

45. Klinefelter Syndrome • Breast development • Small testes • Sterile • Low intelligence • Not retarded Klinefelter Website

46. Turner Syndrome

47. Turner Syndrome • Short • Not go through pruberty • Produce little estrogen • Sterile • Extra skin on neck

48. Fetal Testing

49. Sickle Cell Anemia • RBCs sickle shaped • Anemia • Pain • Stroke • Leg ulcers • Jaundice • Gall stones • Spleen, kidneys & lungs

50. Sickle Cell Anemia • Recessive allele, s codes for hemoglobin S • Long rod-like molecules • Stretches RBC into sickle shape • Homozygous recessive, ss have sickle cell anemia • Heterozygous, Ss are carriers