End Show Slide 1 of 32 Copyright Pearson Prentice Hall 11-1 The Work of Gregor Mendel

End Show 11-1 The Work of Gregor Mendel Slide 2 of 32 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 garden peas. Gregor Mendel’s Peas

End Show 11-1 The Work of Gregor Mendel Slide 3 of 32 Copyright Pearson Prentice Hall Gregor Mendel’s Peas Mendel knew that the male part of each flower produces pollen, (containing sperm). the female part of the flower produces egg cells.

End Show 11-1 The Work of Gregor Mendel Slide 4 of 32 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.

End Show 11-1 The Work of Gregor Mendel Slide 5 of 32 Copyright Pearson Prentice Hall Gregor Mendel’s Peas Pea flowers are self-pollinating. The seeds that are produced by self-pollination inherit all of their characteristics from a single parent plant, so they are clones.

End Show 11-1 The Work of Gregor Mendel Slide 6 of 32 Copyright Pearson Prentice Hall Gregor Mendel’s Peas Mendel developed a process called cross-pollination. He was able to produce seeds that had two different parents.

End Show 11-1 The Work of Gregor Mendel Slide 7 of 32 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. He crossed plants with each of the seven contrasting characteristics and studied their offspring.

End Show 11-1 The Work of Gregor Mendel Slide 8 of 32 Copyright Pearson Prentice Hall Genes and Dominance The 7 traits of pea plants:

End Show 11-1 The Work of Gregor Mendel Slide 9 of 32 Copyright Pearson Prentice Hall Genes and Dominance The original pair of plants is the P (parental) generation. The offspring are called the F 1 generation. Their offspring are called the F 2 generation. The offspring of crosses between parents with different traits are called hybrids.

End Show 11-1 The Work of Gregor Mendel Slide 10 of 32 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.

End Show 11-1 The Work of Gregor Mendel Slide 11 of 32 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.

End Show 11-1 The Work of Gregor Mendel Slide 12 of 32 Copyright Pearson Prentice Hall Genes and Dominance The principle of dominance states that some alleles are dominant and others are recessive.

End Show 11-1 The Work of Gregor Mendel Slide 13 of 32 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.

End Show 11-1 The Work of Gregor Mendel Slide 14 of 32 Copyright Pearson Prentice Hall Segregation 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.

End Show 11-1 The Work of Gregor Mendel Slide 15 of 32 Copyright Pearson Prentice Hall Segregation Alleles separate during gamete formation.

End Show 11-1 The Work of Gregor Mendel Slide 16 of 32 Copyright Pearson Prentice Hall

End Show Slide 17 of 32 Copyright Pearson Prentice Hall 11-1 Gametes are also known as a.genes. b.sex cells. c.alleles. d.hybrids.

End Show Slide 18 of 32 Copyright Pearson Prentice Hall 11-1 The offspring of crosses between parents with different traits are called a.alleles. b.hybrids. c.gametes. d.dominant.

End Show Slide 19 of 32 Copyright Pearson Prentice Hall 11-1 If a particular form of a trait is always present when the allele controlling it is present, then the allele must be a.mixed. b.recessive. c.hybrid. d.dominant.