1. Patterns of Heredity and Human Genetics
Chapter 12

2. Pedigree A graphic representation of genetic inheritance
Circle = female
Square = male
Shaded = exhibits trait
Half-shaded = carrier of trait
Carrier – heterozygous individual

3. Horizontal line = parents or mates
Vertical line = offspring
Each row = a generation

4. Simple Recessive Heredity
Most genetic disorders are caused by recessive alleles
Cystic fibrosis – formation and accumulation of thick mucus in lungs and digestive tract
Tay-Sachs Disease – deterioration of mental abilities because of accumulation of lipids in nervous system
Phenylketonuria – damage to nervous system due to phenylalanine

5. Simple Dominant Heredity
Examples
Cleft chin
Widow’s peak
Hitchhikers thumb
Almond-shaped eyes
Huntington’s disease – results in break down of certain areas of the brain

6. Complex Patterns of Inheritance
Incomplete dominance – get intermediates (blending)
Codominance – both alleles are expressed
Multiple alleles-ABO blood type