What is Genetics? Genetics: Study of heredity Heredity: passing of traits from parent to child Patterns of relatedness can help predict offspring characteristics Autosomal recessive & dominance Sex-Linked Incomplete dominance Codominance

Famous for pea plant studies Mendel studied seven pea plant traits Gregor Mendel “Father of Genetics” Famous for pea plant studies Mendel studied seven pea plant traits Color, shape, texture, height, etc… Results shaped our understanding of genetics

P Generation F1 Generation 100% purple

Gone Forever?

F1 Generation F2 Generation 3 purple: 1 white ratio 75% purple

Mendel's Conclusions Organisms inherit 2 copies of each gene 1 from each parent inside the gametes 1 form of a gene may prevent the expression of the other

Chromosomes and Genes Genes are located on chromosomes Traits are determined by the genes we possess (from mom and dad) Allele: Alternative forms of a gene Letters used to abbreviate alleles Dominant Allele = Capital letter Recessive Allele = Lowercase letter Dominant alleles hide recessive alleles

Common Definitions Phenotype: Actual appearance of a gene Ex: Purple flowers Genotype: Genetic makeup of an organism Ex: 2 dominant alleles (PP) Genotype determines phenotype

Common Definitions Homozygous: Combination of two same alleles PP (homozygous dominant) pp (homozygous recessive) Heterozygous: Combination of 2 different alleles one dominant; one recessive allele Pp (heterozygous dominant)

Quick Review Mendel started work in genetics by studying peas Each trait is determined by two alleles (one from each parent) Dominant alleles hide recessive alleles