Chapter 12.1: Human Traits

Genetic Family Tree Maps only one trait at a time

Pedigrees

Circle = Female Square = Male Shaded = has trait Unshaded = doesn’t show trait Half-shaded = Heterozygous Horizontal line between male and female =

parents Vertical line = parents to kids Each row = generation

How to Read a Pedigree

Most disorders are recessive Cystic Fibrosis Most common in white Americans Defective protein in cells Thick mucus in lungs and stomach Treatment = physical therapy, special diets

and medications

Recessive Disorders

Tay-Sach’s Disease Affects brain and spinal cord Lacking an enzyme that breaks down lipids Lipids accumulate in brain and spinal cord Common in Jewish-Americans and Amish

Recessive cont…

Phenylketonuria (PKU) Phenylalanine (amino acid) accumulates in body Causes severe damage to brain Americans from Norway or Sweden Born normal Infant drinks mom’s milk, which is high in

phenylalanine Causes mental retardation PKU test given to all newborns Treatment = special diet until brain is fully

developed (early 20s)

Recessive cont…

Only need to inherit disease from one parent

Huntingtons Disease Lethal Brain breaks down No treatment Doesn’t show up until 30-50

Dominant Disorders