Mendelian Genetics Part II

Dihybrid Crosses A cross involving 2 traits. Law of Independent Assortment: Genes for different traits can segregate independently during the formation of gametes. Independent Assortment accounts for the many variations in organisms.

Summary of Mendel’s Principles Genes are passed from parent to offspring. Some forms of alleles are dominant and some are recessive. Each person receives 2 copies of each gene, these genes separate when gametes are formed. Alleles for different traits segregate independently.

Beyond Simple Dominance Incomplete Dominance: the heterozygous is an intermediate between the two homozygous. Ex. Red and white makes pink.

Beyond Simple Dominance Codominance: The two homozygous traits are expressed equally in the heterozgyous. Ex. Black and white chickens the heterozygous have both black and white feathers.

Beyond Simple Dominance Multiple Alleles: genes with more than 2 alleles. Ex. Blood type

Beyond Simple Dominance Polygenic Traits: Traits are controlled by two or more genes. Ex. Skin color

Beyond Simple Dominace Sex-Linked Inheritance: genes that are normally found on the X- chromosome. Therefore they are more common in males. Ex. Colorblindness, hemophilia, duchenne Muscular Dystrophy

Used to determine genotypes In order to do a test cross You always cross an unknown Genotype with a known Homozygous recessive individual

Nature vs. Nurture Characteristics are determined by genes and environment. Genes provide the plan for development, how it unfolds depends on the environment.