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Chapter 10.1

Chapter 10.1. Mendel’s Laws of Heredity. Explain fertilization. Fertilization = male gamete ( sperm ) + female gamete ( egg ) Resulting cell is now called a zygote In plants, its called pollination Self-pollination = one plant Cross-pollination = two plants.

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Chapter 10.1

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  1. Chapter 10.1 Mendel’s Laws of Heredity

  2. Explain fertilization. Fertilization = male gamete (sperm) + female gamete (egg) • Resulting cell is now called a zygote • In plants, its called pollination • Self-pollination = one plant • Cross-pollination = two plants www.scienceclarified.com/.../uesc_05_img0247.jpg

  3. Compare and contrast phenotype and genotype Phenotype = physical expression of genes • Ex: Brown hair vs blonde hair Genotype = actual gene combination • Ex: BB, Bb, bb • Homozygous = BB (dominant), bb (recessive) • Heterozygous = Bb

  4. Phenotypes Genotypes

  5. Punnett squares. • Parent’s alleles go on side and top • Carry alleles across or down • Monohybrid Cross = one trait • Dihybrid Cross = two traits

  6. Why is Mendel the “Father of Genetics”? • Mendel studied heredity of traits among pea plants • Study of heredity = genetics • He came up with the basic laws and understanding of genetics mendel.imp.ac.at/mendeljsp/images/mendel2.jpg

  7. Explain the results of Mendel’s Monohybrid Cross. • Some terms • True breeding = many generations carrying the same trait • P = parent • F = filial (son or daughter)

  8. Explain the results of Mendel’s Monohybrid Cross. • Mendel’s cross pollination • TALL plant x short plant (P1 generation) • Result: Hybrids • ALL offspring TALL (F1 generation) • Self pollination of F1 • F1 TALL X self (TALL) • Result • 3/4 TALL and 1/4 short (F2 generation) • We refer to this as a ratio of 3:1

  9. Mendel continued to test this with each of 7 traits. Every time the same ratios appeared… Conclusion: Each organism has 2 factors (genes) that control each of its traits. • Different versions of each factor (gene) is now called an allele • Ex. Gene for height has a tall and short allele

  10. Describe dominant and recessive alleles. • Rule of dominance: in F1 generations the trait that is observed in 100% of the offspring is considered to be the dominant allele. • Dominant alleles (TALL) mask the other form • Recessive alleles (short) get masked by the dominant form • ONLY ONE dominant allele is needed for the form to be expressed! Tt = TALL

  11. Dom. alleles are always written first • Dom. alleles are always given a capital letter, recessive get the lower case letter • EX: for Height • TALL = T or H or Z • Short = t or h or z

  12. Describe Mendel’s Law of Segregation. Every individual has 2 alleles for each gene • Gametes are produced to carry only 1 from you parents • When fertilization occurs you now have 2 alleles, 1 from mom, 1 from dad. • 4 possible combinations ghs.gresham.k12.or.us/.../lawofsegregation.gif

  13. Explain the results of Mendel’s Dihybrid Cross. P1: Round, Yellow x Wrinkled, Green RRYY x rryy F1: 100% Round, Yellow (dihybrids) F2: 9 Round, Yellow: 3 Round, Green : 3 Wrinkled, Yellow : 1 Wrinkled, Green

  14. www.biologycorner.com/.../dihybrid_cross.gif

  15. Describe Mendel’s Law of Independent Assortment. • Genes of different traits are inherited independently when found on different C. • Ex: Not all Blondes have blue eyes

  16. fig.cox.miami.edu/.../150/mitosis/sf9x5b.jpg

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