Integrated Science Ch. 7 Tracking Traits: An Introduction to Genetics to Genetics

Mendel : T he F ounder o f G enetics Heredity -the passing of traits from parent to offspring I.Genetics: -the study of heredity

A.Gregor Mendel: - father of genetics - proposed the Principles of Heredity (1880's) - Austrian monk, taught "high school biology"

B.Experimented with peas - several crops per year - don't take up much space - developed "purebreds"

- easy to control pollinate Pea Flower Stamens (male) produce pollen Pistil (female) produces eggs

- seven distinct, inherited traits Plant size Flower location Flower color Pod color Pod shape Seed shape Seed color

PF1F1

F1F1 F2F2

II.Principles of Heredity II.Principles of Heredity A.Concept of Unit Characters: - traits are controlled by "factors" (genes) which occur in pairs - one from each parent

B.Principle of Dominance and Recessiveness: - some alleles are dominant, or mask, the effect of other alleles - Allele: one of the "versions" of a gene

C.Law of Segregation: - during meiosis (production of gametes), each pair of genes separate

Cross Fertilization of Parents Purebred (Homozygous) Purple-flowered Parent Purebred (Homozygous) White-flowered Parent Cross-Fertilize All Purple-flowered (Heterozygous) Offspring Pollen PP pp P P p p Pp

F1F1 Self-Fertilize F2F2 F2F2 F2F2 F2F2 75% Purple 25% White Self-fertilization of F 2 Pp PP Pp pp

1.Gametes: - specialized, reproductive cells (sperm and egg) - have 1/2 a set of chromosomes Human Egg and Sperm Cells

1.Gametes: 2.Genotype: - genetic make-up of an organism 3.Phenotype: - physical appearance of an organism - specialized, reproductive cells (sperm, egg) - have 1/2 a set of chromosomes

4.Homozygous: - alleles in a gene pair that are identical - TT or tt TTTttt 5.Heterozygous: - alleles in a gene pair that are different - Tt

The End