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 Genetics is the scientific study of heredity. Gregor Mendel Austrian Monk Found how genes are inherited Through pea experiment. 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. Pea flowers are self-pollinating because they Contain both parts (sperm and egg).

End Show 11-1 The Work of Gregor Mendel Slide 5 of 32 Copyright Pearson Prentice Hall Gregor Mendel’s Peas Mendel had true-breeding pea plants that, if allowed to self-pollinate, would produce offspring identical to themselves but… he wanted to prevent this. Mendel took pollen from one plant and crossed it over to another. This was called cross- pollination

End Show 11-1 The Work of Gregor Mendel Slide 6 of 32 Copyright Pearson Prentice Hall Genes and Dominance Mendel ended up studying seven pea plant traits, each with two contrasting characters. A trait is a specific characteristic that varies from one individual to another (seed color, plant height). See chart on Pg. 264

End Show 11-1 The Work of Gregor Mendel Slide 7 of 32 Copyright Pearson Prentice Hall Genes and Dominance Each original pair of plants is the P (parental) generation. The offspring are called the F 1, or “first filial,” generation. Filial means son or daughter. The offspring of crosses between parents with different traits are called hybrids.

End Show 11-1 The Work of Gregor Mendel Slide 8 of 32 Copyright Pearson Prentice Hall Genes and Dominance Mendel’s F 1 Crosses on Pea Plants

End Show 11-1 The Work of Gregor Mendel Slide 9 of 32 Copyright Pearson Prentice Hall Genes and Dominance Mendel’s Seven F 1 Crosses on Pea Plants Mendel’s F 1 Crosses on Pea Plants

End Show 11-1 The Work of Gregor Mendel Slide 10 of 32 Copyright Pearson Prentice Hall Genes and Dominance Mendel's first conclusion We inherit traits passed from one generation to another. 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 For example, the gene for plant height occurs in one form that produces tall plants and in another form that produces short plants. The different forms of a gene are called alleles.

End Show 11-1 The Work of Gregor Mendel Slide 12 of 32 THE PRINCIPLE OF DOMINANCE Mendel’s second conclusion: Copyright Pearson Prentice Hall

End Show 11-1 The Work of Gregor Mendel Slide 13 of 32 Copyright Pearson Prentice Hall Genes and Dominance The principle of dominance states that some alleles are dominant and others are recessive. An organism with a dominant allele for a particular form of a trait will always exhibit that form of the trait. Recessive alleles will only exhibit their traits if the dominant one is not present.

End Show 11-1 The Work of Gregor Mendel Slide 14 of 32 Copyright Pearson Prentice Hall Genes and Dominance Mendel’s F 1 Crosses on Pea Plants

End Show Slide 15 of 32 Mendel wanted to know the answer to another question? Had the recessive alleles disappeared, or were they still present in the F 1 plants? Copyright Pearson Prentice Hall

End Show 11-1 The Work of Gregor Mendel Slide 16 of 32 To answer the question….. Mendel allowed all 7 kinds of F 1 hybrid plants to produce an F 2 (second filial) generation by self- pollination. Copyright Pearson Prentice Hall

End Show 11-1 The Work of Gregor Mendel Slide 17 of 32 Copyright Pearson Prentice Hall Mendel's F 2 Generation P Generation F 1 Generation Tall Short F 2 Generation Segregation

End Show 11-1 The Work of Gregor Mendel Slide 18 of 32 Copyright Pearson Prentice Hall Segregation The reappearance of the trait controlled by the recessive allele indicated that at some point the allele for shortness had been separated, or segregated, from the allele for tallness.

End Show 11-1 The Work of Gregor Mendel Slide 19 of 32 Copyright Pearson Prentice Hall Segregation Mendel suggested that the alleles for tallness and shortness in the F 1 plants segregated from each other during the formation of the sex cells, or gametes.

End Show - or - Continue to: Click to Launch: Slide 20 of 32 Copyright Pearson Prentice Hall 11-1

End Show Slide 21 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 22 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 23 of 32 Copyright Pearson Prentice Hall 11-1 In Mendel’s pea experiments, the male gametes are the a.eggs. b.seeds. c.pollen. d.sperm.

End Show Slide 24 of 32 Copyright Pearson Prentice Hall 11-1 In a cross of a true-breeding tall pea plant with a true-breeding short pea plant, the F 1 generation consists of a.all short plants. b.all tall plants. c.half tall plants and half short plants. d.all plants of intermediate height.

End Show Slide 25 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.

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