- Slides: 8
Genetics • Genetics: the scientific study of heredity (how characteristics are passed from parents to offspring) • The principles of genetics were founded by Gregor Mendel.
Gregor Mendel • He was an Austrian monk who studied garden pea plants. • He observed seven characteristics or traits of the pea plants
Mendel’s Methods • He collected seeds from different plants, planted them, and observed the characteristics of the new pea plant generation.
Plant Pollination • Mendel controlled the pollination of his pea plants. • Pollination: when pollen grains made in male reproductive part of a flower (anthers) are transferred to the female reproductive part (stigma). • Self-pollination: when pollen from one flower is transferred to the stigma of the same flower. • Cross-pollination: when pollen from one flower is transferred to the stigma of a flower from a different plant.
Mendel’s Experiments • P 1 generation (parental generation): pure strains for each trait created by allowing the plants to self-pollinate for several generations. • ex. a plant pure for yellow pods will only produce offspring with yellow pods. • F 1 generation (first filial generation): involves a crosspollination between two P 1 generation plants pure for each contrasting trait. • ex. green pods (pure P 1) X yellow pods (pure P 1) • F 2 generation (second filial generation): involves the selfpollination of the F 1 generation.
Mendel’s Results/Conclusions • Mendel hypothesized that each trait was inherited by a separate factor. He reasoned that their must be a pair of factors that controls each trait.
Mendel’s Two Laws (1) Law of Segregation: a pair of traits is segregated, or separated, during the production of gametes. • gametes (sex cells) only have one factor of each trait pair. • when two gametes join or fertilize the offspring will have both factors that control a specific trait. (2) Law of Independent Assortment: factors for different traits are distributed to gametes independently. • dominant traits are not connected or inherited with other dominant traits. All separate traits are independent of one another.