Genetic Diseases Disorders Biology n Huntingtons diseaselethal genetic

Genetic Diseases & Disorders Biology

n 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

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

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

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

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

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

n n 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

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

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

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

Spleen infected with sickle cells

Genetic Disorders n 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

Genetic Disorders n Hemophilia— a recessive, sex-linked trait located on the X chromosome that causes problems with blood clotting n 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? _______

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

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

Downs Syndrome: n n n 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=To. NWquo. X q. JI