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Bellwork

Bellwork . What is genetics? The study of heredity What is heredity? The study of how traits are passed on from parent(s) to offspring. Chapter 10: Genetics (scientific study of heredity). 10.1 and 10.2: Work of Gregor Mendel. Gregor Mendel. His occupations: monk, gardener, teacher

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Bellwork

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  1. Bellwork What is genetics? The study of heredity What is heredity? The study of how traits are passed on from parent(s) to offspring

  2. Chapter 10: Genetics (scientific study of heredity) 10.1 and 10.2: Work of Gregor Mendel

  3. Gregor Mendel • His occupations: monk, gardener, teacher • His nickname: Father of Genetics

  4. Gregor Mendel • What was the purpose for Mendel’s studies? To understand the method of heredity • What organism did he work with? Pea plants

  5. Pea Plants • Anatomy of Pea Plant • Female Reproductive organ: pistil • Male Reproductive organ: stamen (pollen) • How are new seeds created? Stamen (pollen) fertilize the pistil • True-breeding (purebred) organisms: they can produce offspring that are identical to themselves • Self-pollination vs. Cross pollination

  6. Mendel’s Experiments • How did he prevent self-pollination from occurring? He removed the pistil from one plant and the stamen from the other.

  7. What 7 traits did Mendel study? • Seed Shape • Seed Color • Seed Coat • Pod Shape • Pod Color • Flower Position • Plant Height

  8. Figure 11-3 Mendel’s Seven F1 Crosses on Pea Plants Each gene comes in two different forms called alleles. Seed Shape Seed Color Seed Coat Color Pod Shape Pod Color Flower Position Plant Height Round Yellow Gray Smooth Green Axial Tall Wrinkled Green White Constricted Yellow Terminal Short Round Yellow Gray Smooth Green Axial Tall Go to Section:

  9. Seed color: yellow and green • Yellow is dominant Y • Green is recessive y

  10. Alleles: different forms of a gene *Organisms have two different alleles for each trait Why? Dominant alleles: capital letter Recessive alleles: lowercase letters. Example: Gene for plant height (t) Dominant form: T (tall) Recessive form :t (short) TT tt Tt

  11. Genes • Genotype: genetic makeup; what is on your DNA • Consists of 2 alleles Tt • Phenotype: physical characteristics “Genotype and environment determines your phenotype”

  12. Mendel’s First Experiment • Mendel crossed plants with different forms of the same trait Example: He crossed true-breeding yellow pod plant and true-breeding green pod plant. • Original plants that mated: P (parental) generation. • Offspring:F1(filial) generation. • RESULT: All offspring were green

  13. The Result of the Cross: • The offspring of parents with different traits are called hybrids. • The offspring showed the trait of only one of the parents. Why? • MENDEL’S CONCLUSIONS: 1. Genes are inherited.

  14. 2. Principle of Dominance: “Some alleles are dominant, some alleles are recessive” • In order to show a dominant form of a trait you need to have at least one dominant allele. • In order to show a recessive form of a trait you need to have two recessive alleles. Plant Height TT Tt tt • T-tall • t-short

  15. Mendel’s 2nd Experiment • He allowed the F1 offspring to self-pollinate, to produce a F2 generation of plants.

  16. Results: ¾ green plants ¼ yellow plants.

  17. Mendel’s conclusions: Law of Segregation: During the formation of gametes (meiosis), the paired alleles are separated from each other. Each gamete carries only a single allele from the original pair. They randomly unite at fertilization. For each trait, the offspring inherit one allele from each parent. Example: True-breeding green pod plants GG True-breeding yellow pod plants gg F1 Offspring were Gg (hybrids)

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