CH 11 Introduction to Genetics 11-1 The Work of Gregor Mendel

Gregor Mendel Austrian monk born 1822 Austrian monk born 1822 Worked at a monastery as a priest, teacher, and was in charge of gardening Worked at a monastery as a priest, teacher, and was in charge of gardening Studied the genetics of ordinary pea plants Studied the genetics of ordinary pea plants Genetics - scientific study of heredity Genetics - scientific study of heredity

Fertilization During sexual reproduction, male and female reproductive cells join During sexual reproduction, male and female reproductive cells join Gametes – sex cells Gametes – sex cells True-breeding – produce offspring identical to parents when self-pollinate True-breeding – produce offspring identical to parents when self-pollinate Mendel was interested in cross-pollinating plants with different traits Mendel was interested in cross-pollinating plants with different traits

Genes and Dominance Trait – a specific characteristic Trait – a specific characteristic Mendel studied 7 traits in pea plants Mendel studied 7 traits in pea plants Hybrid – offspring of parents with different traits Hybrid – offspring of parents with different traits Genes – chemical factors that determine traits Genes – chemical factors that determine traits

Alleles Different forms of a gene (e.g. height can be tall or short) Different forms of a gene (e.g. height can be tall or short) Some alleles are dominant and others are recessive Some alleles are dominant and others are recessive

Names of Generations P generation – parents P generation – parents F1 – first filial, first generation of offspring F1 – first filial, first generation of offspring F2 – second filial, second generation of offspring F2 – second filial, second generation of offspring

Segregation Separation of alleles Separation of alleles Mendel – “do recessive alleles disappear when P generations produce offspring?” Mendel – “do recessive alleles disappear when P generations produce offspring?” No - when F1 offspring are crossed recessive alleles reappear in the F2 generation (25% show it) No - when F1 offspring are crossed recessive alleles reappear in the F2 generation (25% show it)