Genetics Introduction and Vocabulary

History of Genetics Gregor Johann Mendel is the father of genetics Modern genetics are based on Mendel’s explanations for the patterns of heredity in pea plants Mendel’s experiments involved crossing different types of pea plants Crossing means to mate or to breed

Why Pea Plants? Plants have contrasting traits Usually self-pollinates Ex: Tall vs. short, or purple vs. white Usually self-pollinates Fertilizes itself rather than another plant Fertilizing another plant is called cross-fertilization Grows easily

Mendel’s First Experiment - True breeding purple plants were crossed with true- breeding white plants. These plants are called the P generation. The resulting plants are called the F1 generation. All plants in the F1 generation had purple flowers. Two plants from the F1 generation were crossed to produce the F2 generation. ¾ of the plants in the F2 generation were purple and ¼ were white. http://go.hrw.com/resources/go_sc/interactOnline/hx/hxgen _io.swf

Mendel’s Theories Mendelian theory of heredity: Inheritance involves the passing of genes from parents to offspring. Different traits result in different versions of genes. These different versions of genes are called alleles. One allele comes from each parent Ex: Dad gives you freckles and your mom does not

Mendel’s Theories Law of segregation: During reproduction, the alleles that determine traits are separated into reproductive cells via meiosis and randomly reunite during fertilization

Mendel’s Theories Law of independent assortment: Genes located on different chromosomes will be inherited independently of each other.