Gregor Mendel and Genetics The Work of Mendel Genetics = scientific study of heredity Heredity = characteristics that are passed on to the next generation.
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Presentation on theme: "Gregor Mendel and Genetics The Work of Mendel Genetics = scientific study of heredity Heredity = characteristics that are passed on to the next generation."— Presentation transcript:
The Work of Mendel Genetics = scientific study of heredity Heredity = characteristics that are passed on to the next generation Gregor Mendel (1800’s) –Grew up as a peasant farmer –Austrian Monk, high school science teacher, in charge of monastery gardens. –Used garden peas for experiments
Mendel was successful because: peas are self-pollinating (inherit all characteristics from plant that bore them) Had true breeding stock = basis for experiment Can cross pollinate (uses 2 parents) Controlled experiment Kept careful records !
Traits studied Chose several traits that were true-breeding and had two distinct forms Seed shape: round vs wrinkled Seed color: Yellow vs green Gray seed coat vs white seed coat Smooth pod shape vs constricted pod Pod color = green vs yellow Flower position = axial vs terminal Height = tall vs short
Mendel’s Experiment P = parental generation, original pair, true breeding, tall x short Cross pollination: F1 generation = first filial generation results in hybrids (from parents with contrasting traits) results: all tall Self pollination: F2 generation = second filial generation ¾ tall, ¼ short
MENDEL’S CONCLUSION: “Factors” governed the expression of each trait (factors now called ?) Each trait = controlled by a pair of genes, two factors (ex. 1 for tall, 1 for short) Allele = different forms of a trait, one of the gene pair
Principle of Dominance 1 of the genes in a pair may prevent the other gene from being expressed. Dominant gene = one which masks the other in a pair Recessive gene = one which is hidden (may reappear in F2) Dominant allele = expressed by a capital letter (ex. Y = yellow) Recessive allele = lower case (ex. y = green)
Principle of Segregation Members of each pair of genes separate during gamete formation **********