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Do Now

Do Now. Why are Traffic lights, always laid out in this manner? Red on top, Yellow in the middle, green on the bottom? For those that are Color Blind. Why is it a male dominated condition ? Write out the question and your answer. Homework.

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Do Now

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  1. Do Now • Why are Traffic lights, always laid out in this manner? Red on top, Yellow in the middle, green on the bottom? • For those that are Color Blind. • Why is it a male dominated condition? Write out the question and your answer.

  2. Homework • Due today was to read pages 395 – 397 and take notes including the following: • Sex-linked genes • X-Chromosome Inactivation • Pedigree • Due for next class (Friday) – Read pages 398 – 400 the section deals with Human Genetic Disorders

  3. Review • Colorblindness is Sex-linked inherence: • It is carried on the X chromosome. For a female to carry the recessive gene she would have to have it on both the X chromosome. Since males only have one X chromosome it cannot be cancelled out with the other sex chromosome gene since it is Y. • This is why it is far more likely to find a male with color-blindness than a female.

  4. Inbreeding • Explain the problem with continuous breeding of an individual with similar characteristics. • What is the term? • Inbreeding which is too close to one another genetically so both the good genes and the bad can remain, and be expressed. Much like the Amish where after a few generations there is very little variation.

  5. New stuff • X-Chromosome inactivation – in females since there are two X-Chromosomes, one of the X-Chromosomes typically is shut off. Sometimes they are both on, sometimes both off. • When shut off it is called inactivation. • In male cats, for example, since there is on one X-Chromosome, the cat will only have one additional color of fur.

  6. Pedigree • Looks at the pattern of inheritance. The pedigree looks at the presence or absence of a particular trait. • For example looking Sickle Cell Anemia or hemophilia. Like in the British Royal Family

  7. Human genetic Disorders • Sickle Cell Disease is most often found in people of African ancestry. • People with Sickle Cell Disease have a defective allele for beta-globin found in hemoglobin. Hemoglobin is the oxygen carrying protein in red blood cells. • The defect makes the Hemoglobin less soluble, causing Hemoglobin molecules to stick together and be less effective. • The molecules clump together giving them the half-moon shape and these get stuck in capillaries causing blood to clot.

  8. Human genetic Disorders • Cystic Fibrosis is most often found in people of European ancestry. • It develops because three bases did not form. • This is a genetic trait, many people are carriers of the disease and never know it because they have no signs of it. They must mate with someone that is also a carrier of CF. • CF effects the lungs ability breath properly.

  9. Typhoid Mary • Irish cook Mary Mallon (1869-1938) was dubbed "Typhoid Mary" by the media after she infected dozens of people with the dreaded disease. • When Mallon worked as a cook at the turn of the century, typhoid fever was a highly contagious disease and a serious threat to the public health. Mallon was the first identified person who carried and spread the disease without ever exhibiting the symptoms. At least three deaths and 53 cases of typhoid were directly linked to her, with thousands of other probable cases.

  10. Was she immune or just a carrier? • Some question as to whether she had CF in some form. Many in Europe (those most affected by CF) had developed a resistance to typhoid. The CF allele blocks the entry of bacterium typhoid. Those with a heterozygous for CF would develop an immunity.

  11. Gene therapy • Gene therapy is a technique for correcting defective genes responsible for disease development (four types) • 1. A normal gene may be inserted into a nonspecific location within the genome to replace a nonfunctional gene. • 2. An abnormal gene could be swapped for a normal gene. • 3. The abnormal gene could be repaired through selective reverse mutation, and returns it normal function

  12. Gene therapy continued • 4. The regulation (the degree to which a gene is turned on or off) of a particular gene could be altered.

  13. Human Genetic Disorders • Cystic Fibrosis- in your own words explain • 1. What does it do? • 2. How does it occur? • Sickle Cell Anemia • 1. What does it do? • 2. How does it impact?

  14. Advantage of a genetic disorder? • Cystic Fibrosis – Thought to prevent Typhoid from occurring. In old Europe typhoid was common and the body seems to have adapted to prevent it by developing CF.

  15. Sickle Cell Anemia • Remember that evidence points to higher survival rates for Africans where Malaria exists. Sickle Cell seems to have mutated and allowed Africans to survive in areas where Malaria exists

  16. Nature’s way to deal with change • Organisms that face environmental change have 3 choices • 1. Adapt to the change in environment • 2. Move away from the new condition • 3. Die

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