Chapter 11.1 notes


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Chapter 11.1 notes

  1. 1. Chpt. 11.1 Basic Patterns of Human Inheritance
  2. 2. Pedigrees <ul><li>Pedigree – a diagram that traces the inheritance of a particular trait through several generations. </li></ul><ul><li>Carrier – heterozygous individual. They carry the trait but don't express the trait. </li></ul>
  3. 3. Reading a Pedigree
  4. 4. Inheritance of Human Traits
  5. 5. Dominant Genetic Disorders
  6. 6. Dominant Genetic Disorders <ul><li>Caused by DOMINANT alleles </li></ul><ul><li>Such as RR or Rr </li></ul>
  7. 7. Huntington’s Disease <ul><li>Rare but lethal genetic disorder (1/10,000) </li></ul><ul><li>Onset between 30-50 years of age </li></ul><ul><li>Caused by a rare autosomal (not sex chromosome) dominant allele </li></ul><ul><li>Lethal disorder – a disease that causes death in most of the individuals who are affected </li></ul><ul><li>The nervous system undergoes progressive degeneration, resulting in uncontrolled, jerky movements of the head and limbs and mental deterioration </li></ul><ul><li>No cure or treatment </li></ul>
  8. 8. Huntington disease, a disease of the nervous system, is caused by an autosomal dominant gene.
  9. 9. Pedigree for Huntington’s Disease
  10. 10. Achondroplasia <ul><li>Affects bone growth of individuals (1/25,000) </li></ul><ul><li>Causes small body size and limbs that are short with large head. </li></ul><ul><li>Most common form of dwarfism </li></ul><ul><li>Adult height of 4 feet with normal life expectancy. </li></ul><ul><li>No cure or treatment </li></ul>
  11. 11. Recessive Genetic Disorders
  12. 13. Cystic Fibrosis <ul><li>The most common lethal genetic disorder among white Americans (1/3,500) </li></ul><ul><li>1 in 20 white Americans is a carrier </li></ul><ul><li>1 in 2000 children born to white Americans inherits the disorder </li></ul><ul><li>Kills about 500 children/young adults each year </li></ul><ul><li>Affects the mucus-producing glands, digestive enzymes, and sweat glands </li></ul><ul><li>Chloride ions are not absorbed into the cells but are excreted in the sweat. Without sufficient chloride ions in the cells, a thick mucus is secreted. </li></ul>
  13. 14. Cystic Fibrosis Symptoms <ul><li>Mucus in lungs & digestive tract is thick </li></ul><ul><li>Breathing is difficult </li></ul><ul><li>Lung infections are frequent </li></ul><ul><li>Mucus slows secretion of some digestive enzymes, prevents proper digestion </li></ul><ul><li>Physical therapy, special diets, & new drugs have raised the average life expectancy </li></ul><ul><li>No cure </li></ul>
  14. 15. Albinism <ul><li>Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes </li></ul><ul><li>-White hair </li></ul><ul><li>-Very pale skin </li></ul><ul><li>-Pink pupils </li></ul><ul><li>Occurs 1 in 17,000 </li></ul><ul><li>No cure </li></ul>
  15. 16. Tay-Sachs Disease <ul><li>Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides </li></ul><ul><li>Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration. </li></ul><ul><li>Identified by cherry-red spot in back of the eye. </li></ul><ul><li>Found on chromosome 15 </li></ul><ul><li>Affects people of Jewish descent (1/2,500) </li></ul><ul><li>Death by age 5 </li></ul><ul><li>No cure or treatment </li></ul>
  16. 18. Galactosemia <ul><li>Characterized by the inability of the body to digest galactose. </li></ul><ul><li>Lactose (from milk) breaks down into galactose and glucose. Galactose is broken down by the enzyme GALT. People with galactosemia lack or have a defective GALT. </li></ul><ul><li>Will result in mental disabilities, enlarged liver and kidney failure. </li></ul><ul><li>Occurs in 1/50,000-70,000 </li></ul><ul><li>No cure but must restrict lactose/galactose I diet. </li></ul>