Mendel

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Chapter 10.1

• Mendels Laws of Heredity

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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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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

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Phenotypes
Genotypes
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Punnett squares.

• Parents alleles go on side and top
• Carry alleles across or down
• Monohybrid Cross one trait
• Dihybrid Cross two traits

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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

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Explain the results of Mendels Monohybrid Cross.

• Some terms
• True breeding many generations carrying the
  same trait
• P parent
• F filial (son or daughter)

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Explain the results of Mendels Monohybrid Cross.

• Mendels 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 31

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• 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

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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

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• 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

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Describe Mendels 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

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Explain the results of Mendels 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

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Describe Mendels Law of Independent Assortment.

• Genes of different traits are inherited
  independently when found on different C.
• Ex Not all Blondes have blue eyes

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