Every living organisms consists of one or more cells The cell is the structural and functional unit of life. All living cells arise by division of preexisting cells. Cells contain hereditary material, which they pass on to their offspring during division.

the study of heredity – how traits are passed down to offspring a characteristic that varies among individuals in a population a segment of DNA that codes for specific traits different forms of the same trait ex. hair color ex. brunette, blonde, red, black, brown

an Austrian monk in the 1800’s who contributed much to our understanding of genetics

There is variation in pea plants: round vs wrinkled seeds, green vs yellow peas, tall vs short plants Traits are passed down from parent to offspring Purpose: to study patterns of inheritance

1. True Breeding: breed pea plants through self-fertilization over many generations until they all had the same trait Mendel created a population of only yellow peas and a separate population of only green peas.

2. Cross-Pollination: remove the stamen (containing pollen) from one flower; use a brush to transfer pollen from another flower 3. Cross-pollinate a (P) yellow pea plant with a (P) green pea plant

Parents First-generation offspring Second-generation offspring Third-generation offspring

(P) Pure Yellow Pea Plant x (P) Pure Green Pea Plant 100% Yellow Pea Plant Offspring

4. Using flowers from the first generation of offspring, cross- pollinate a (F1) yellow pea plant with a (F1) yellow pea plant

(F1) Hybrid Yellow Pea Plant x (F1) Hybrid Yellow Pea Plant 75% Yellow Pea Plants and 25% Green Pea Plants

Because yellow peas x green peas yielded only yellow offspring, yellow coloring is dominant to green coloring. Because 1 st generation hybrids yielded both yellow and green offspring, some genetic material from green pea parent was still passed down to the offspring.

Some alleles are dominant (T) and others are recessive (t) An organism with a dominant allele for a trait will always exhibit that form of the trait. An organism with a recessive alleles for a trait will only exhibit that form when the dominant allele is absent.

having both dominant alleles ex. BB having both recessive alleles ex. bb having both dominant and recessive alleles ex. Bb

the genetic make-upthe physical appearance of a genotype Widow’s Peak