Human Inheritance

1. Human Inheritance Chromosomes = contain the GENES = estimated approximately 50,000 genes/set of chromosomes *Genotype provides the POTENTIAL for development. *Phenotype is also a result of environmental factors!!!!!!!! (diet, climate, education, etc.)

2. Human Inheritance (cont’d) Sex-Linked Traits = traits linked to the sex chromosomes or a particular sex. 1. Sex – limited traits = genes expressed in only 1 sex ex; heavy beard mammary glands

4. Human Inheritance (cont’d) 2. Sex – Influenced Traits = traits dominant in one sex, and recessive in the other. ex; baldness - gene is dominant in males - gene is recessive in females

7. Human Inheritance (cont’d) 3. X-linked traits = traits linked to the X chromosome ex; Hemophilia - lack of blood clotting factor = arthritis due to bleeding into the joints = uncontrollable internal bleeding

8. Human Inheritance (cont’d) ex; Duchennes Muscular Dystrophy = lack of muscle protein (dystrophen) - causes muscle deterioration - death by early adulthood - males with DMD don’t reproduce - 1/3500 affected/year - ALL MALES

10. Human Inheritance (cont’d) ex; Soft Tooth enamel - teeth deteriorate/fall out.

11. Human Inheritance (cont’d) 4. Y-Linked Trait = Trait linked to the Y chromosome - passed on only from father to son ex; Testis Determining Factor - gene that brings about male characteristics at maturity. - lack of = female phenotype.

13. Human Inheritance (cont’d) ex; Hairy Pinnae = hairy ears

14. Human Inheritance (cont’d) 5. Other sex-linked traits (nondisjunction) Turners Syndrome = Missing Y chromosome = genotype XO - girl appears normal, as they age they are shorter/stockier than normal, sex organs and breasts don’t develop.

15. Turner’s Syndrome

17. Human Inheritance (cont’d) Klinefelters Syndrome - male with XXY genotype - develop enlarged breasts, high pitched voices, sterile and below normal intelligence.

19. Human Inheritance (cont’d) Other genetic diseases; AUTOSOMAL 1. Recessive a. Sickle Cell Disease (SCD) - 1/400 births/year (mainly blacks) - effects Red Blood Cells (RBC’s)

20. Human Inheritance (cont’d) - normal = disc shaped - carries hemoglobin which carries O2 to body. - mutated gene = RBC’s sickle shaped - fragile/break easily = anemia – lack of RBC’s. = greater risk of infections

22. Human Inheritance (cont’d) b. Cystic Fibrosis (CF) = most common genetic disorder among caucasians - 1/20 whites are a carrier for CF. = ? Children/year ? = increase mucous production = increase in RTI’s. ( ) - usually cause of death in 20’s

23. Human Inheritance (cont’d) c. Phenylketonuria (PKU) - 1/10,000 births = inability to break down common amino acid PHENYLALANINE (PHE). - too much PHE = damage to the CNS = severe retardation ** every newborn is tested before 1 week old…if positive, put on diet low in PHE until brain is fully developed

24. Human Inheritance (cont’d) d. Tay-Sachs Disease (TSD) - 1/3600 births = at age of 1, begin with deterioration of the CNS, leading to severe retardation and blindness. - death by the age of 4.

25. Human Inheritance (cont’d) 2. Dominant a. Huntington’s Disease (HD) - 1/15,000 births = results in mental deterioration and personality changes, may have spasmatic muscle movements ** average age of onset = 38

26. Human Inheritance (cont’d) b. Familial Hypocholesterolemia (FH) - due to Incomplete Dominance f = normal F = FH ff = normal cholesterol level Ff = 2x the cholesterol level - heart attack by 30’s FF = 6x the cholesterol level - heart attack by preschool

27. Human Inheritance (cont’d) 3. Nondisjunction = when chromosomes don’t separate correctly during Meiosis. - extra/missing chromosomes

28. Human Inheritance (cont’d) a. Down Syndrome - trisomy 21 = extra chromosome in the 21st position. = mental retardation, almond shaped eyes, short limbs, thick tongues

29. Human Inheritance (cont’d) Pedigree = a chart used to show the inheritance of a trait through a family. male female male/carrier female/carri. male/affected female/affec.

30. Human Inheritance (cont’d) T= normal, t = tay-sachs • Tt x Tt • Offspring of I; A.- male – tt B.- female – Tt - marries male TT C.- male – TT – marries female Tt • Couple B has 2 boys one is Tt, the other TT Couple C has 1 girl with genotype of Tt

31. Human Inheritance (cont’d) Detecting disorders before birth: by examining the FETUS = developing offspring inside the mother • Ultrasound = use of high frequency sound waves reflected off of the fetus - picture produced on screen - shows size/position of fetus - can detect some physical abnormalities

32. Human Inheritance (cont’d) 2. Fetoscopy = using a slender tube with a light/camera attached to get a close up view of the fetus inside the mother. - 5%

33. Human Inheritance (cont’d) 3. Amniocentesis = Use a needle to remove a small amount of amniotic fluid from around the fetus. - fluid contains fetal cells that are used to make a karyotype -- shows abnormal, missing or extra chromosomes and sex of fetus. -- can be done after the 4th month -- ½ %

35. Human Inheritance (cont’d) 4. Chorionic Villus Sampling (CVS) = remove a small piece of the chorionic membrane from around the fetus. - make a karyotype - done after 9 weeks - 1.5%