If you have completed a first-year high school biology course, some of this chapter will serve as a review for the basic concepts of Mendelian genetics. For other students, this may be your first exposure to genetics. In either case, this is a chapter that should be carefully mastered. Spending some time with this chapter, especially working genetics problems, will give you a solid foundation for the extensive genetics unit in the chapters to come. | Chapter 14 Mendel and the Gene Idea Mendel’s Experimental, Quantitative Approach Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments. Advantages of pea plants for genetic study: There are many varieties with distinct heritable features, or characters (such as flower color); character variants (such as purple or white flowers) are called traits. Mating of plants can be controlled. Each pea plant has sperm-producing organs (stamens) and egg-producing organs (carpels). Cross-pollination (fertilization between different plants) can be achieved by dusting one plant with pollen from another. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Crossing pea plants TECHNIQUE RESULTS Parental generation (P) Stamens Carpel 1 2 3 4 First filial gener- ation offspring (F1) 5 Mendel chose to track only those characters that varied in an either-or manner => Clear contrasting traits. He also used varieties that were true-breeding / pure (plants that produce offspring of the same variety when they self-pollinate). Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings In a typical experiment, Mendel mated two contrasting, true-breeding (opposite pures) varieties, a process called hybridization. The true-breeding parents (opposite pures) are the P generation. The hybrid offspring of the P generation are called the F1 generation. When F1 individuals self-pollinate, the F2 generation is produced. The hybrid cross (F1 mated with another F1) produces the most variety in offspring (F2 ). Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Mendel: The Law of Dominance and the Law of Segregation Law of Dominance: When Mendel crossed contrasting, true-breeding white and purple flowered pea plants, all of the F1 hybrids were purple. Law of Segregation: When Mendel crossed the F1 hybrids, many of the F2 plants had purple . | Chapter 14 Mendel and the Gene Idea Mendel’s Experimental, Quantitative Approach Mendel discovered the basic principles of heredity by breeding garden peas in carefully planned experiments. Advantages of pea plants for genetic study: There are many varieties with distinct heritable features, or characters (such as flower color); character variants (such as purple or white flowers) are called traits. Mating of plants can be controlled. Each pea plant has sperm-producing organs (stamens) and egg-producing organs (carpels). Cross-pollination (fertilization between different plants) can be achieved by dusting one plant with pollen from another. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Crossing pea plants TECHNIQUE RESULTS Parental generation (P) Stamens Carpel 1 2 3 4 First filial gener- ation offspring (F1) 5 Mendel chose to track only those characters that varied in an either-or manner => Clear contrasting traits. He also .
