Chapter 11 Genetic Disorders Biology Chapter 11 Genetic Disorders

Human Genetic Disorders Cystic Fibrosis Most common in whites 1 in 20 people are a carrier Mucus clogs lungs Failure of chloride ion transport protein Recessive

Human Genetic Disorders Huntington’s Disease Dominant Symptoms usually do not appear until later in life Brain cells deteriorate

Human Genetic Disorders Sickle Cell Anemia Mostly in African Americans; 1 in 500 Caused by a single amino acid change in the 574 aa protein. Instead of glutamine, there is valine This disorder prevents hemoglobin (carrier of oxygen) to work properly

Human Genetic Disorders Hemophilia Sex-linked recessive (on the X chromosome) Failure of blood to clot Missing a clotting factor in the blood

Human Genetic Disorders Color Blindness Sex-linked recessive Inability to distinguish between colors (red and green look brown) Missing a receptor to code for the colors

Human Genetic Disorders Trisomy – Presence of three of one kind of chromosome Karyotype – Map (picture) of human chromosomes

Human Genetic Disorders Down Syndrome Recessive Have extra copy of 21st chromosome Caused by nondisjunction (failure of chromosomes to separate during meiosis) or by part breaking off and fusing to # 14

Human Genetic Disorders Prevention Genetic counseling – Amniocentesis: Sample of the fluid surrounding a fetus is extracted and examined. Can obtain a karyotype

Human Genetic Disorders Prevention Usually need an ultra sound before amniocentesis (after 14th week) Chorionic Villus Biopsy: Can be performed in 9th week. Take cells from the chorion, tissue where fetus is linked to mother. Can analyze and determine a karyotype