Genetics I Gregor Mendel A He carried out

Genetics

I. Gregor Mendel A. He carried out the first study of heredity - the passing on of characteristics from parents to offspring B. Genetics - the branch of biology that studies heredity 1. Traits characteristics that are inherited

Why study pea plant? ► Things to consider: § Reproduction § Growth § What you can observe § What you can manipulate § What makes your job easier

C. Mendel studied pea plants to study heredity. WHY? ? 1. Easy to grow 2. Definite sex organs 3. 7 distinguishable traits

SEED SHAPE SEED COLOR POD SHAPE FLOWER COLOR FLOWER LOCATION PLANT SIZE 5

II. Terminology A. Phenotype - physical or observable quality (hair color, height, finger #) B. Genotype - genetic make-up called genes (hair can be brown, red, black, blond…) *Gentoype determines the phenotype GENOTYPE = gg PHENOTYPE = white

C. Alleles - the alternative forms of a gene D. Homozygous - two alleles for the trait are the same (AA or aa) E. Heterozygous - two alleles for a trait differ from one another (Aa)

III. Mendel’s results Law of Independent assortment - genes for different characteristics are distributed to gametes independently. (Gene for eye color does NOT affect gene for hair type) 1. Principle of dominance and recessiveness each organism has two factors a. Dominant - a trait that dominates or masks another trait (A) b. Recessive - trait does not appear (a) Law of segregation – when an individual produces gametes, the copies of a gene separate, so each gamete only receives 1 copy.

IV. Mendel - Father of Genetics ► He didn’t know about chromosomes, genes, or meiosis ► His principles are still true today