04 mendelian genetics and humans

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04 mendelian genetics and humans

  1. 1. MENDELIAN GENETICS AND HUMANS
  2. 2. Mid-digital hair – dominant Tongue rolling – dominant Widow's peak – dominant Earlobes – dominant Hitchhiker's thumb less than 45° - dominant Relative finger length An interesting sex influenced (not sex-linked) trait relates to the relative lengths of the index and ring finger. In males, the allele for a short index finger (S) is dominant. In females, it is recessive. In rare cases each hand may be different. If one or both index fingers are greater than or equal to the length of the ring finger, the recessive genotype is present in males and the dominant present in females. MENDELIAN GENETICS AND HUMANS Human Traits
  3. 3. MENDELIAN GENETICS AND HUMANS Human Blood Groups Let the allele for blood type be represented by “I” I A = Type A (dominant) I B = Type B (dominant) i = Type O (recessive) codominant
  4. 4. MENDELIAN GENETICS AND HUMANS Human Blood Groups I A = Type A (dominant) I B = Type B (dominant) i = Type O (recessive) Anti A, Anti B Type O ii O None Type AB I A I B AB Anti-A Type B I B i or I B I B B Anti-B Type A I A i or I A I A A Antibody Antigen (phenotype) Genotype Blood Types
  5. 5. MENDELIAN GENETICS AND HUMANS Human Blood Groups What are the genotype and phenotype ratios of the offspring between a Type AB male and Type O female? Parent genotypes: I A I B x ii Therefore: F1 genotypes 1 I A i : 1 I B i F1 phenotypes 1 Type A : 1 Type B I B i I A i i I B i I A i i I B I A
  6. 6. MENDELIAN GENETICS AND HUMANS Human Blood Groups Is it possible for a Type A father and a Type B mother to produce Type O children? Let’s assume the parents are homozygous I A I A and I B I B Parent genotypes: I A I A x I B I B Parent gametes: I A I A x I B I B Therefore: F1 genotypes 100% I A I B F1 phenotypes 100% Type AB blood None of the children have O-type blood. So let’s assume the parents are both heterozygous I A I B I A I B I B I A I B I A I B I B I A I A
  7. 7. MENDELIAN GENETICS AND HUMANS Human Blood Groups Is it possible for a Type A father and a Type B mother to produce Type O children? Let’s assume the parents are heterozygous I A i and I B i Parent genotypes: I A i x I B i Parent gametes: I A i x I B i Therefore: F1 genotypes 25% I A I B 25% I A i 25% I B i 25% ii F1 phenotypes 25% Type A, 25% Type B, 25% Type AB, and 25% Type O So it IS possible!!! i i I A i i I B i I A I B I B i I A
  8. 8. MENDELIAN GENETICS AND HUMANS Inheritance Patterns Autosomal recessive: Involves a recessive allele on a non-sex chromosome Autosomal dominant: Involves a dominant allele on a non-sex chromosome X-linked recessive: Involves a recessive allele on the X-chromosome X-linked dominant: Involves a dominant allele on the X-chromosome Y-linked: Involves an allele on the Y-chromosome
  9. 9. MENDELIAN GENETICS AND HUMANS Human genetic disorders Progeria <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal dominant </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Premature aging, prematurely old </li></ul><ul><li>Few exceed 13 years old </li></ul><ul><li>90% die from complications from atherosclerosis </li></ul>
  10. 10. MENDELIAN GENETICS AND HUMANS Human genetic disorders Huntington disease <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal dominant </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Progressive brain disorder causing uncontrolled movements and loss of cognition </li></ul><ul><li>May live for 15-20 years after onset of symptoms </li></ul><ul><li>Trouble eating, swallowing, talking, etc. </li></ul>
  11. 11. MENDELIAN GENETICS AND HUMANS Human genetic disorders Tay Sachs Disease <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Nerve cells destroyed in brain and spinal cord </li></ul><ul><li>Symptoms appear 3-6 months after birth </li></ul><ul><li>Loss of motor control and atrophy of muscles, seizures </li></ul><ul><li>Death </li></ul>
  12. 12. MENDELIAN GENETICS AND HUMANS Human genetic disorders Phenylkentonuria (PKU) <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Permanent intellectual disability, seizures </li></ul><ul><li>Symptoms appear a few months after birth </li></ul><ul><li>May have a “musty” odour </li></ul>
  13. 13. MENDELIAN GENETICS AND HUMANS Human genetic disorders Albinism <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Lack of melanin in skin, hair, and/or eyes </li></ul><ul><li>May have vision problems </li></ul><ul><li>Sensitivity to UV light </li></ul>
  14. 14. MENDELIAN GENETICS AND HUMANS Human genetic disorders Familial hypercholesterolemia (FH) <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal dominant </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Very high levels of cholesterol in blood </li></ul><ul><li>Buildup of excess cholesterol in various bodily tissues </li></ul><ul><li>High risk of atherosclerosis </li></ul>
  15. 15. MENDELIAN GENETICS AND HUMANS Human genetic disorders Sickle cell anemia <ul><li>Inheritance Pattern: </li></ul><ul><li>-Autosomal recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Shortness of breath, fatigue, delayed growth and development in children </li></ul><ul><li>May experience painful episodes of anemia resulting in organ damage </li></ul>
  16. 16. MENDELIAN GENETICS AND HUMANS Human genetic disorders Hemophilia A <ul><li>Inheritance Pattern: </li></ul><ul><li>-X-linked recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Excessive bleeding from minor cuts </li></ul><ul><li>Extensive bruises </li></ul>
  17. 17. MENDELIAN GENETICS AND HUMANS Human genetic disorders Colour blindness <ul><li>Inheritance Pattern: </li></ul><ul><li>-X-linked recessive (red-green and blue colour defects) </li></ul><ul><li>- Autosomal recessive (blue-yellow) </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Inability to perceive various colours </li></ul>
  18. 18. MENDELIAN GENETICS AND HUMANS Human genetic disorders Duchenne muscular dystrophy <ul><li>Inheritance Pattern: </li></ul><ul><li>-X-linked recessive </li></ul><ul><li>Physical Effects: </li></ul><ul><li>Muscle weakness, delayed motor development in children </li></ul><ul><li>Wheelchair dependence by adolescence </li></ul><ul><li>Enlargement and weakening of the heart </li></ul>

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