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Human Genetic Traits

Human Genetic Traits. Importance of genetics. Understanding hereditary diseases and to develop new treatments Organ donor matches Paternity Forensics Evolution. Genes - genetic material on a chromosome that codes for a specific trait

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Human Genetic Traits

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  1. Human Genetic Traits

  2. Importance of genetics • Understanding hereditary diseases and to develop new treatments • Organ donor matches • Paternity • Forensics • Evolution

  3. Genes- genetic material on a chromosome that codes for a specific trait Genotype- the genetic makeup of the organism for a trait Phenotype- the physically expressed trait (what you look like) Allele- alternative forms of a gene (comes in dominant & recessive)

  4. Gregor Mendel’s Law of Complete Dominance • Two alleles are carried for each trait • In true-breeding individuals, both alleles are the same (homozygous). • Hybrids, on the other hand, have one of each kind of allele (heterozygous). • The dominant allele form covers the recessive allele form

  5. Genetic Information • Genes produce proteins • Proteins (brown eye pigment, hair shape) • Trait (how you look; phenotype)

  6. Homologous Chromosomes- pair of chromosomes that contain the same genes (one from mom/one dad)

  7. Allele Example • Gene = “eye color” • Alleles (gene forms possible) • brown • blue • green • lavender

  8. Allele Examples appearance eye color:Homozygous (both alleles same)

  9. Allele Examples appearance eye color:Heterozygous (Bb), Two different alleles (brown dominant over blue)

  10. Genotype vs Phenotype genotype phenotype homozygous(dominant) heterozygous homozygous (recessive)

  11. STOP HERE

  12. Punnett Square If male & female are heterozygous for eye color male female X brown: 3/4 offspring blue: 1/4 offspring

  13. PKU Each parent carries one gene for PKU. P p P P P P p P p X P p P p p p p Possible genotypes: 1PP 2Pp 1pp Possible phenotypes:no PKU PKU

  14. Compare this to what would have happened if one parent was homozygous for sickle cell. HbA HbA HbA HbA HbS HbA HbA HbS HbS X HbA HbA HbS HbS HbS HbS HbS all offspring are carriers of sickle cell trait

  15. Autosomes and Sex Chromosomes

  16. Red-Green Color Blindness Sex-linked trait XC Y XC Y XC XC XC Normal male XC Y X XC Xc XC Xc Xc Xc Y Normal female recessive gene Possible outcomes: XCXC XCXc XCY XcY Normal female Normal Female (carrier) Normal male Color-blind male

  17. Dominance Most traits show complete dominance Blending unexpected

  18. allele gene E unconnected earlobe e connected earlobe unconnected P EE x ee connected E e gametes F1 Ee

  19. F1 Ee x Ee 1/2 E 1/2 e1/2 E 1/2 e gametes E e E EE Ee PunnettSquare e Ee ee F2 1 EE 2 Ee 1 ee

  20. generation genotypes unconnected E:e P EE, ee 50% 1:1 F1 Ee 100% 1:1 F2 EE, 2 Ee, ee 75% 1:1 phenotypes ratio of alleles in the population Basis of the Castle-Hardy-Weinberg Law

  21. Genotypes Phenotypes Experiment to determinedominant vs. recessive

  22. Genetic Sleuthing My eye color phenotype is brown. What is my genotype?

  23. Pedigree phenotypes infer genotypes Alternative: look directly at the DNA

  24. Complexities • Multiple genes for one trait • Example: eye color • Blended traits (“incomplete dominance”) • Influence of the environment

  25. Disorders Down’s Syndrome (chrom 21) Alzheimer’s (chrom 1, 10, 14, 19, 21) Huntington’s (chrom 4)

  26. Human Genetic Traits

  27. Tongue Roller R = Tongue Rollerr = Unable to Roll Tongue

  28. Widow’s Peak W = Widows Peakw = Lack of Widow’s Peak

  29. Free Ear Lobe Attached Ear Lobe E = Free Ear Lobee = Attached Ear Lobe

  30. Hitchhiker’s Thumb Hi = Straight Thumbhi = Hitchhiker’s Thumb

  31. Bent Little Finger Bf = Bent Little Fingerbf = Straight Little Finger

  32. Mid-digital Hair M = Mid-Digital Hairm = Absence of Mid-Digital Hair

  33. Dimples D = Dimplesd = Absence of Dimples

  34. Short Hallux Ha = Short Halluxha = Long Hallux

  35. Short Index Finger Ss = Short Index FingerS1 = Long Index Finger *Sex-Influenced Trait

  36. Kiss me, you fool. Pttttthhhhhhhtttt! Presentation created by J. Kenyon

  37. Genetic Testing • Would you want to know? • Ethical concerns • Cost • Insurance companies • see GATTACA

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