Chapter 5 Section 1

1. Chapter 5 Section 1 Mendel’s Work

2. Gregor Mendel • A priest in Europe during the 1800’s that worked in a monastery garden and taught high school. • Considered the “Father of Genetics” • Most famous for growing and studying pea plants and heredity • Heredity is the passing of physical traits from parents to offspring • Physical traits are characteristics you can see • Genetics is the study of heredity

3. Mendel’s Experiments • Crossing (Mating) Pea Plants • Mendel first created purebred pea plants • A purebred organism always produces offspring with the same trait as the parent (tall plant produces more tall plants) • These were the parent (P) plants • Mendel crossed tall purebred pea plants with short purebred plants • The offspring (F1 generation) were all (100%) tall • Mendel crossed the F1 generation plants • The offspring (F2 generation) were 75% tall 25% short

4. Dominant and Recessive Alleles • Mendel concluded that there were “factors” that control traits • These factors are now called genes • Alleles are different forms of a gene • There are two alleles for each trait. One from each parent. • A dominant allele always shows up • Shown by a upper case letter (T = allele for tall pea plant) • TT (purebred) and Tt (hybrid) will result in a tall plant • A recessive allele is hidden when a dominant is present • Shown with a lower case letter (t = allele for short pea plant) • Recessive traits only show up if there are two recessive alleles. • tt (purebred) will result in a short pea plant