Chapter 12 - Patterns of inheritance, after studying this chapter, you should be able to accomplish the following outcomes: List the approaches to science that made Gregor Mendel's genetic experiments successful, define Mendel's law of segregation, contrast dominant alleles with recessive alleles, define genotype and phenotype,. | Patterns of Inheritance Chapter 12 Early Ideas of Heredity Before the 20th century, 2 concepts were the basis for ideas about heredity: -heredity occurs within species -traits are transmitted directly from parent to offspring This led to the belief that inheritance is a matter of blending traits from the parents. Early Ideas of Heredity Botanists in the 18th and 19th centuries produced hybrid plants. When the hybrids were crossed with each other, some of the offspring resembled the original strains, rather than the hybrid strains. This evidence contradicted the idea that traits are directly passed from parent to offspring. Early Ideas of Heredity Gregor Mendel -chose to study pea plants because: 1. other research showed that pea hybrids could be produced 2. many pea varieties were available 3. peas are small plants and easy to grow 4. peas can self-fertilize or be cross-fertilized Early Ideas of Heredity Mendel’s experimental method: 1. produce true-breeding strains for each trait he was studying 2. cross-fertilize true-breeding strains having alternate forms of a trait -perform reciprocal crosses as well 3. allow the hybrid offspring to self-fertilize and count the number of offspring showing each form of the trait Monohybrid Crosses Monohybrid cross: a cross to study only 2 variations of a single trait Mendel produced true-breeding pea strains for 7 different traits -each trait had 2 alternate forms (variations) -Mendel cross-fertilized the 2 true-breeding strains for each trait Monohybrid Crosses F1 generation (1st filial generation): offspring produced by crossing 2 true-breeding strains For every trait Mendel studied, all F1 plants resembled only 1 parent -no plants with characteristics intermediate between the 2 parents were produced Monohybrid Crosses F1 generation: offspring resulting from a cross of true-breeding parents F2 generation: offspring resulting from the self-fertilization of F1 plants dominant: the form of . | Patterns of Inheritance Chapter 12 Early Ideas of Heredity Before the 20th century, 2 concepts were the basis for ideas about heredity: -heredity occurs within species -traits are transmitted directly from parent to offspring This led to the belief that inheritance is a matter of blending traits from the parents. Early Ideas of Heredity Botanists in the 18th and 19th centuries produced hybrid plants. When the hybrids were crossed with each other, some of the offspring resembled the original strains, rather than the hybrid strains. This evidence contradicted the idea that traits are directly passed from parent to offspring. Early Ideas of Heredity Gregor Mendel -chose to study pea plants because: 1. other research showed that pea hybrids could be produced 2. many pea varieties were available 3. peas are small plants and easy to grow 4. peas can self-fertilize or be cross-fertilized Early Ideas of Heredity Mendel’s experimental method: 1. produce true-breeding strains .
