PEDIGREES (12.3) * a chart that shows how a trait and the genes that control it are inherited within a family. Symbols: female male mate/ marriage offspring

USES helpful in determining carriers (an individual who carries a recessive trait that is not expressed). to determine whether a trait is dominant or recessive. to determine whether a trait is heterozygous or homozygous dominant to determine whether a trait is sex-linked

Examples of recessive traits Tay-Sachs disease Cystic fibrosis Albinism *The allele is preserved in the population because the carriers are NOT affected.

Examples of dominant traits Freckles Widow’s peak Polydactyly Huntington’s disease *In many cases, a person who has inherited a dominant allele that produces a fatal disorder is likely to result in an early death…why is this important?