Heredity Why we look the way we do.

Who is this man? Why does he matter?

Gregor Mendel Austrian Monk – well educated Father of genetics! Published his work in 1866 but was not (rediscovered until 1900 Researched pea plants – found mathematical relationship

Genetics : the scientific study of heredity – How genes (traits) are expressed – How genes (traits) are passed from one generation to the next.

Mendel’s Laws Traits come in pairs (1 Maternal, 1 Paternal) Some traits are dominant, while others are recessive. Law of Independent Assortment: traits sort themselves independently. (Metaphase I) Law of Segregation: traits separate during the formation of gametes. (Anaphase II)

Genetics Terms Alleles: one or more alternate forms of a trait. Example: Hitchhiker vs. Straight Thumbs, Straight Hair Line vs. Widow’s Peak Homozygous : a pair of alleles that are identical. – Purebred Heterozygous: a pair of alleles that are different. – Hybrid

Dominant: alleles that are always expressed. – Symbolize with CAPITAL LETTERS Recessive: alleles that are only expressed when paired with another recessive allele. – Symbolize with lowercase letters Allele Description

Genotype: describing an organism in terms of the individual’s genes. – Symbolized with letters Phenotype: describing an organism in terms of physical characteristics. – Actual description of what you would see

Complete Dominance

A cross of two individuals that only focuses on one trait. Monohybrid Cross

Probability: the likelihood that something will occur. Punnett Square: a diagram that helps visualize the possible offspring from a cross of two individuals.

Punnett Squares Reginald Crundall Punnet – British Mathematician – Wrote the first popular science book – Mendelism – Created the Punnett Square