Chpt. 11.2 complex inheritance leftovers


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Chpt. 11.2 complex inheritance leftovers

  1. 1. Complex Patterns of Inheritance
  2. 2. Sickle-cell anemia <ul><li>Autosomal recessive trait </li></ul><ul><li>1 in 12 African Americans (black Americans whose families originated in Africa) is heterozygous (carrier) </li></ul><ul><li>Common in white Americans whose families originated in the countries surrounding the Mediterranean Sea </li></ul>
  3. 3. <ul><li>Person suffers from anemia (low # rbc) </li></ul><ul><li>Abnormally shaped cells slow blood flow, block small vessels, and results in tissue damage and pain </li></ul><ul><li>Have other serious health problems because of the impaired circulation </li></ul><ul><li>Treatments – blood transfusion and drug therapy </li></ul>
  4. 5. Sex Determination <ul><li>Sex chromosomes determine an individual’s gender. </li></ul><ul><li>Humans have 23 pair (46 total) of chromosomes in each of somatic cells </li></ul><ul><li>22 are autosomes </li></ul><ul><li>The 23rd pair are sex chromosomes </li></ul><ul><ul><li>XX = female </li></ul></ul><ul><ul><li>XY = male </li></ul></ul>
  5. 6. Dosage Compensation <ul><li>The X chromosome carries a variety of genes that are necessary for the development of both females and males. </li></ul><ul><li>The Y chromosome mainly has genes that relate to the development of male characteristics. </li></ul>
  6. 7. Chromosome Inactivation <ul><li>Chromosome Inactivation- random inactivation of the X chromosome. </li></ul><ul><li>Example – calico cat </li></ul><ul><li>One X chromosome codes for orange fur and one X chromosome codes for black fur. </li></ul>
  7. 8. Sex linked traits <ul><li>Sex-linked traits (X-linked)- traits controlled by genes located on the X chromosome. </li></ul><ul><li>X-linked inheritance - passed on by the female – even if recessive, the trait is expressed because the male does not pass an X for a dominant allele. </li></ul><ul><li>Ex: Color blindness and hemophilia </li></ul>
  8. 10. Muscular dystrophy is a deadly disorder in which the muscles grow progressively weaker. The disease is caused by a recessive gene on the X chromosome
  9. 11. Polygenic Inheritance <ul><li>Polygenic Inheritance- pattern of a trait that is controlled by two or more genes </li></ul><ul><li>Genes may be on the same chromosome or different chromosome </li></ul><ul><li>All heterozygotes are intermediate in phenotype </li></ul>
  10. 12. Polygenic Inheritance <ul><li>Inheritance pattern of a trait that is controlled by two or more genes </li></ul><ul><li>Skin color, eye color </li></ul><ul><li>Will express a range of colors (intermediate) </li></ul>
  11. 13. Environmental Influences <ul><li>The environment also has an effect on phenotype. As organisms develop many factors influence how genes will be expressed </li></ul><ul><li>2 environmental influences </li></ul><ul><li>Internal environment- Male and females express traits differently due to hormones </li></ul><ul><li>-Horn size in rams, feather color in peacocks </li></ul><ul><li>-Age affects how genes function </li></ul><ul><li>External environment- Temperature, nutrition, light, chemicals, and infectious agents </li></ul>
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