2. Genetic Diseases & Disorders Biology

3. Huntington’s disease-- lethal genetic disorder resulting in a breakdown in areas of the brain. Onset occurs between the ages of 30 and 50 years of age

4. Huntington’s Disease: Dominant Lethal Affects 30-50 Uncontrolled jerky movements of head & limbs Mental deterioration Problem: have already passed it on before being diagnosed.

5. Recessive Disorders Most Genetic disorders—caused by recessive alleles Cystic fibrosis— Common among white Americans, causes the formation and accumulation of thick mucous in the lungs and digestive tract

6. Cystic Fibrosis: Recessive Lethal (late 30’s currently) White Americans Thick mucus in lungs & digestive tract making breathing difficult.

7. Tay-Sachs disease— Recessive disorder more common in among Jewish, causes a build up of lipids in the brain cells III IV 1 3 2 4 3

8. Tay- Sachs Recessive Lethal Begin at age 1, most die by age 5 Blindness Loss of movement Mental retardation Lipids accumulate in brain

9. Phenylketonuria (PKU)—Recessive disorder in which the body cannot break down amino acid phenylalanine, causes severe damage to the central nervous system and mental retardation Phenylalanine—used as a sweetener in diet soda, anyone with PKU cannot consume diet soda

10. Phenyl- Ketonuria: Recessive Treatable Norweigan, Suisse PKU accumulates in central nervous system Mental retardation Now tested for shortly after birth

11. Genetic Disorders Sickle-cell anemia— a co-dominant trait that affects the shape of red blood cells Most common in African Americans

12. Sickle Cell Anemia Hemoglobin—protein that carries oxygen in blood, makes blood red In homozygous individuals—hemoglobin is defective and makes blood cells sickle (half moon) shaped These blood cells—cause slow blood flow, block small vessels, tissue damage and pain In heterozygous individuals – both normal and sickled hemoglobin are produced They produce enough normal hemoglobin that they do not have serious health problems

13. Spleen infected with sickle cells

15. Genetic Disorders Red-green color blindness – a recessive, sex-linked trait located on the X chromosome that results in individuals being unable to see red and green colors

17. Genetic Disorders Hemophilia— a recessive, sex-linked trait located on the X chromosome that causes problems with blood clotting Cuts take a long time to stop bleeding, and bruising and internal bleeding are dangerous If a male has hemophilia, from which parent did he inherit the disorder from? ______________ If a female has hemophilia, from which parent did she inherit the disorder from? ______________

18. Hemophilia: X-linked Treatable, can be LETHAL Males Blood doesn’t Clot

19. Genetic Disorders Trisomy 21 (Down Syndrome)—when an individual has 3 copies of chromosome number 21 Causes some degree of mental retardation in affected individuals Can be identified on a karyotype

20. Downs Syndrome: 3 chromosomes on 21 pair Not lethal (shorter lifespan) Older mothers (over 40) Mental retardation Short stature Other trisomy disorders are generally fatal - https://www.youtube.com/watch?v=ToNWquoX qJI https://www.youtube.com/watch?v=ToNWquoX qJI