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Genetic Disorders

Genetic Disorders. Genetic Disorders Can Result from. INHERITANCE. MUTATIONS. The inheritance of a dominant or recessive trait. The inheritance of a sex-linked trait. Exposure to outside factors. Mistakes during meiosis. Mutations. Changes in genes.

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Genetic Disorders

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  1. Genetic Disorders

  2. Genetic Disorders Can Result from INHERITANCE MUTATIONS The inheritance of a dominant or recessive trait The inheritance of a sex-linked trait Exposure to outside factors Mistakes during meiosis

  3. Mutations • Changes in genes. • Sometimes result in traits that are expressed differently. • Can be harmful or helpful.

  4. Environmental Factors UV-RAYS X-RAYS RADIOACTIVESUBSTANCES CHEMICALS

  5. On April 26, 1986 at the Chernobyl Nuclear Power Plant in the Ukraine a sudden power outage caused series of nuclear explosions. The worst nuclear power plant accident in history caused mutations in the population that have been passed down to the children of Chernobyl.

  6. MUTATIONS Exposure to outside factors Mistakes during meiosis X-rays UV-rays Chemicals Radioactive Substances Children of Chernobyl

  7. Chromosome Disorders MUTATIONS • Mistakes during meiosis can result in an organism having too many or too few chromosomes. • A change in the total number of human chromosomes is usually fatal to the unborn embryo or fetus, or the baby may die soon after birth. • Disorders occur when the incorrect number of chromosomes is inherited. • Example: • Down’s Syndrome- occurs when three copies of chromosome 21 are produced in the female egg. Mistakes during meiosis Too Many or Too Few Chromosomes Example: Down’s Syndrome

  8. Down’s Syndrome • Shorter than average • Over-sized tongue • Poor muscle tone • Almond-shaped eyes • Exhibit learning disabilities • Have heart problems • Can live normal lives if they have no severe health complications. 3 copies of chromosome 21

  9. Dominant Genetic Disorders INHERITANCE • Only one mutated copy of a gene is necessary for a person to be affected by a dominant genetic disorder. • Examples include: • Huntington’s Disease (Hh or HH) • Marfan’s Syndrome (Mm or MM) • Ahondroplasia (Dwarfism) (Dd or DD) Inheritance of a dominant or recessive trait Dominant Genetic Disorders Huntington’s Disease (Hh or HH) Marfan’s Syndrome (Mm or MM) Dwarfism (Dd or DD)

  10. Huntington’s Disease • A progressive brain disorder that causes involuntary, rapid, jerky movements and mental deterioration.

  11. Marfan’s Syndrome • A disorder of the body’s connective tissue. • Affected people often have extra long limbs and stooped shoulders. Their eyeballs have a blueish tint.

  12. Ahondroplasia (Dwarfism) • Body size is extremely smaller than normal. • Limbs are very short but the body’s trunk is almost normal in size. • Have normal intelligence and can lead healthy lives.

  13. Genetics Problem 1 Dwarfism (D) is a dominant trait in humans. Suppose Snowhite(dd) mates with Grumpy(Dd). What is the probability that their child will have the disorder?

  14. dd x Dd d d 50% D Dd dd d Dd dd

  15. Recessive Genetic Disorders INHERITANCE • Caused when both parents supply a recessive gene to an offspring. • Some tend to affect people of one particular ethnic background at a higher rate than the rest of the population. • Examples include: • Cystic Fibrosis (cc) • Tay-Sachs Syndrome (tt) • Sickle-Cell Anemia (ss) Inheritance of a dominant or recessive trait Recessive Genetic Disorders Cystic Fibrosis (cc) Tay –Sachs (tt) Sickle- Cell Anemia (ss)

  16. Cystic Fibrosis • Most common recessive disorder. • 5% of Caucasians are carriers of the disease. • Causes excessive secretion of unusually thick mucus that clogs the lungs. • People with the disease usually die before the age of 20.

  17. Sickle-Cell Anemia • A blood disorder that affects hemoglobin, the protein found in red blood cells, that helps carry oxygen throughout the body. • Characterized by “sickle-shaped” red blood cells. • Symptoms include: jaundice, fatigue, and severe pain throughout body parts.

  18. Tay-Sachs Syndrome • A fatal disorder in which harmful quantities of a fatty substance build up in the brain. • Infants appear to develop normally for the first months of life. • As nerve tissues are destroyed, the baby becomes blind, deaf, and unable to swallow. Thereafter, the infant becomes paralyzed and dies within 4 years.

  19. Genetics Problem 2 Popeye and Olive Oil have a baby who develops TaySach’s Syndrome at the age of 2 months. If the baby has a genotype of (tt) for the disorder, what are the genotypes of the parents?

  20. Both parents are heterozygous Mother: Tt Father: Tt

  21. Sex-Linked Genetic Disorders INHERITANCE • Inherited through one of the sex chromosomes – X or Y. • Females carry the disorder if it is on one X chromosome and they are affected by the disorder if it is on both X chromosomes. • If a male has the disorder on his X or Y chromosome, he is affected by the disorder. • Examples of sex-linked genetic disorders: • Y-chromosome Infertility (XYi) • Hemophilia (XhXh or XhY) • Colorblindness (XcXc or XcY) The inheritance of a sex-linked trait X-chromosome Genetic Disorders Y-chromosome Genetic Disorders Hemophilia Affected: (XhXh or XhY) Carrier: XhX Y- Chromosome Infertility (XYi) Colorblindness Affected: (XcXc or XcY) Carrier: XcX

  22. Y Chromosome Infertility • Caused by deletions that occur on the Y chromosome. • Affects the production of sperm, making it difficult or impossible for a male to father children. • The mutation will be inherited on the y chromosome of any son that an affected male fathers.

  23. Hemophilia • An inherited bleeding disorder in which blood does not clot normally. • The defective gene is found on the x chromosome and is recessive. • Women may have the disease or carry the disease. • If the defective gene is found on a man’s x chromosome, he will have the disorder. Queen Victoria’s “Curse”

  24. Colorblindness • Inability to perceive difference between some colors. • The defective gene is found on the x chromosome and is recessive. • Women may have the disease or carry the disease. • XX- normal female • XcX- carrier female • XcXc- colorblind female • If the defective gene is found on a man’s x chromosome, he will have the disorder. • XY- normal male • XcY-colorblind male

  25. Genetics Problem 3 Wilma is colorblind(xcxc) and Fred is normal (xy). What is the probability that Pebbles is colorblind?

  26. XcXc x XY xc xc x xcx xcx y xcy xcy O% Females would be carriers

  27. Genetics Problem 4 Queen Victoria is a carrier for hemophilia (xhx). She married Prince Albert (xy).The royal couple’s eighth child, Leopold, had hemophilia and suffered from frequent hemorrhages. What is the probability that Leopald’s sister was a hemophiliac?

  28. XhX x XY xh x x xhx xx O% Females would be carriers or normal y xhy xy

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