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Medical Genetics

Medical Genetics. Human Anatomy and Physiology II Oklahoma City Community College. Dennis Anderson. Produces daughter cells with 46 chromosomes Used in growth and repair. Mitosis. Mitosis. DNA is duplicated Doubled chromosomes form from duplicated DNA Each cms has 2 identical chromatids.

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Medical Genetics

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  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

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