1. Copyright Pearson Prentice Hall 11-1 The Work of Gregor Mendel

2. Copyright Pearson Prentice Hall Gregor Mendel’s Peas Genetics is the scientific study of heredity. Gregor Mendel was an Austrian monk. His work was important to the understanding of heredity. Mendel carried out his work with ordinary garden peas. Gregor Mendel’s Peas

3. Copyright Pearson Prentice Hall Gregor Mendel’s Peas During sexual reproduction, sperm and egg cells join in a process called fertilization. Fertilization produces a new cell called a zygote.

4. Copyright Pearson Prentice Hall Genes and Dominance A trait is a specific characteristic that varies from one individual to another. Mendel studied seven pea plant traits, each with two contrasting characteristics.

5. Genes and Dominance The 7 traits of pea plants:

6. Copyright Pearson Prentice Hall Genes and Dominance Each original pair of plants is the P (parental) generation. The offspring are called the F1, or “first filial,” generation. parent plant x parent plant (P generation) offspring (F1 generation) The offspring of crosses between parents with different traits are called hybrids.

7. Copyright Pearson Prentice Hall Genes and Dominance Mendel’s 2 Laws  1. Law of Dominance Mendel's first conclusion was that biological inheritance is determined by “factors” that are passed from one generation to the next. Today, scientists call the “factors” that determine traits genes.

8. Copyright Pearson Prentice Hall Genes and Dominance Each of the traits Mendel studied was controlled by one gene that occurred in two contrasting forms that produced different characteristics for each trait The different forms of a gene are called alleles. Organisms receive 2 copies of the gene and the alleles are the forms of the gene.

9. Copyright Pearson Prentice Hall Genes and Dominance T he principle of dominance states that some alleles are dominant and others are recessive.

10. Copyright Pearson Prentice Hall Genes and Dominance An organism with a dominant allele for a trait will always exhibit that form of the trait. An organism with the recessive allele for a trait will exhibit that form only when the dominant allele for that trait is not present.

11. Copyright Pearson Prentice Hall Segregation 2. Mendel’s Law of Segregation  When any organism produces gametes, the two alleles segregate from each other so that each gamete carries only a single copy of each gene.

12. Copyright Pearson Prentice Hall Segregation

13. Copyright Pearson Prentice Hall