Complex Inheritance and Human Heredity Chapter 11 Complex Inheritance and Human Heredity

11.1 Basic patterns of human inheritance Main idea: The inheritance of a trait over several generations can be shown in a pedigree

Recessive Genetic Disorders A recessive trait is only expressed when the individual is homozygous recessive If the individual has at least 1 dominant allele will not express the recessive trait

Recessive Genetic Disorders Carrier-an individual who is heterozygous for the recessive disorder

Recessive Genetic Disorders Cystic Fibrosis- A defective gene causes a thick mucus to be produced that clogs the lungs and obstruct the pancreas Albinism- Results in the absence of the skin pigment melanin in hair and eyes

Recessive Genetic Disorders Tay-Sachs disease is a fatal genetic disorder in which harmful quantities of a fatty substance build up in tissues and the brain Galactosemia is caused by the lack of a liver enzyme required to digest galactose, a product of lactose

Dominant Genetic Disorders Some genetic disorders can be caused by dominant alleles People unaffected would be homozygous recessive

Dominant Genetic Disorders Huntingtons Disease- causes degeneration of brain cells, leads to uncontrolled movements, and loss of intellectual faculties Achondroplasia- bone growth disorder that results in short stature

Pedigree A pedigree is a diagram that traces inheritance of a trait through generations

Pedigree A pedigree uses symbols to illustrate the inheritance of a trait