Pedigrees & Pattern of Gene Inheritance

Target #19- I can describe the layout & purpose of a pedigree

Many human disorders are genetic in origin Genetic disorders are medical conditions caused by alleles

inherited from the parents Diagrammed in a pedigree

Pedigree: a chart of a family’s history with regard to a particular genetic trait Males are designated as squares Females are designated as circles A line between a square and a circle represents a mating A vertical line going downward leads to a child of the mating

• Child are listed in age from left to right Generations are identified with a roman numeral

Purpose of a pedigree is to follow the inheritance pattern of a particular trait

• Affect individuals are usually shaded

Target #20- I can identify the genotypes of a pedigree

Target #21- I can differentiate between autosomal recessive and autosomal dominant disorders

Autosomal recessive disorders Can be carried by the parents, and

expressed by the child Parents are heterozygous for disorder Examples

Cystic fibrosis Tay-Sachs Sickle-cell anemia

Autosomal dominant disorders Can be expressed by parents if they

are heterozygous and not passed to the child Examples

Marfan Syndrome Huntington disease