Question

What is required for an autosomal recessive disorder to appear? Name four autosomal recessive disorders. What is required for an autosomal dominant disorder to appear? Name two autosomal dominant disorders. (pages \(474-77\) )

Short answer

For an autosomal recessive disorder to appear, an individual must inherit two copies of the recessive gene, one from each parent. Four examples of autosomal recessive disorders are cystic fibrosis, sickle cell anemia, Tay-Sachs disease, and phenylketonuria (PKU). An autosomal dominant disorder appears when an individual inherits just one copy of the dominant gene. Two examples of autosomal dominant disorders are Huntington's disease and Marfan syndrome.

Step-by-step solution

Conditions for an Autosomal Recessive Disorder to Appear

Autosomal recessive disorders occur when an individual inherits two copies of the recessive gene associated with the disorder, one from each parent. In order to have the autosomal recessive disorder, the person must be homozygous for the recessive gene (i.e., carry two copies of the recessive allele).

Four Autosomal Recessive Disorders

Here are four examples of autosomal recessive disorders: 1. Cystic fibrosis: a genetic disorder that affects the lungs, pancreas, and other organs, resulting in difficulty breathing and frequent lung infections 2. Sickle cell anemia: a genetic disorder that affects the shape and functionality of red blood cells, leading to anemia and other complications 3. Tay-Sachs disease: a rare and fatal genetic disorder that progressively destroys nerve cells in the brain and spinal cord 4. Phenylketonuria (PKU): a genetic disorder that prevents the body from breaking down the amino acid phenylalanine, leading to intellectual disabilities if not treated with a strict diet.

Conditions for an Autosomal Dominant Disorder to Appear

Autosomal dominant disorders occur when an individual inherits just one copy of the dominant gene associated with the disorder. If a person has one dominant allele and one recessive allele (heterozygous), they will express the dominant trait and have the autosomal dominant disorder. Thus, inheriting one copy of the abnormal gene from either parent is sufficient for the disorder to appear.

Two Autosomal Dominant Disorders

Here are two examples of autosomal dominant disorders: 1. Huntington's disease: a genetic disorder that affects the brain, leading to the progressive loss of muscle coordination and cognitive decline 2. Marfan syndrome: a genetic disorder that affects the body's connective tissue, leading to problems with the skeletal system, cardiovascular system, and eyes.