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Mendelian Genetics

Mendelian Genetics. The Father of Genetics. Gregor Mendel A monk that worked with pea genetics. Purple vs. White - Flowers Yellow vs. Green - Pea Color Round vs. Wrinkled - Pea Shape Tall vs. Short - Plant Size Genetics is the study of how traits are passed

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Mendelian Genetics

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  1. Mendelian Genetics

  2. The Father of Genetics • Gregor Mendel • A monk that worked with pea genetics. • Purple vs. White - Flowers • Yellow vs. Green - Pea Color • Round vs. Wrinkled - Pea Shape • Tall vs. Short - Plant Size • Genetics is the study of how traits are passed to offspring.

  3. The Father of Genetics • Gregor Mendel discovered that different versions (alleles) of traits exist. • For each trait an organism inherits one version (allele) from each parent. • If the two versions (alleles) are different then one dominates over the other. • The two versions (alleles) separate during gamete production.

  4. Genes and Traits • Genes code for protein that makes a trait. • There can be different versions of a trait. • EX: eye color is a trait. • Blue • Green • Brown • These are different versions of the trait eye color. Different versions are called alleles.

  5. Chromosomes and Genes • Homologous chromosomes – one from mom and one from dad. • Both have the same genes but each can have different alleles (different versions of the same gene).

  6. Chromosomes and Genes • Phenotype = trait = nose size • Genotype = gene letters = GG • Maternal chromosome can have G or g (big or small) • Fraternal chromosome can have G or g (big or small) g g G G g g G G

  7. Chromosomes and Genes • G is dominant over g • GG or Gg = a big nose • g is recessive under G • gg = a small nose • Gg = heterozygous (different)(hybrid) • GG or gg = homozygous (same)(pure breed) g g G G g g G G

  8. What kind of gametes can we get? • Gametes are made by what process? • Meiosis!

  9. Punnet Squares • Take the genotype of both parents. • EX: father = Gg x mother = gg • During meiosis and gamete production the two alleles are separated. (independent assortment) Gg gg G g g g gg will produce these gametes. GG will produce these gametes. Which two gametes will form a zygote?

  10. Punnet Squares Dominant: ( ) ______________________ Recessive: ( ) ______________________ Parents: GG X gg Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________

  11. Punnet Squares Dominant: ( ) ______________________ Recessive: ( ) ______________________ Parents: Gg X Gg Possible Sperm: ______ Possible Egg: ______ Offspring: Genotypes: __________________ Ratio: _______________________ Phenotypes: _________________ Ratio: _______________________

  12. G g g Gg gg G GG Gg P  F1 F2 Mom’s gametes G G g Gg Gg Dad’s gametes • P = parents (GG gg) • F1 = 100% Gg & big nose • F2 = 3:1 phenotype • F2 = 1:2:1 genotype g Gg Gg Mom’s gametes Dad’s gametes

  13. PROBABILITY • If I flip a coin. What can I get? • Heads or Tails • If I flip a coin 10 times what should I get? • 5 Heads & 5 Tails? • How many times can I get a heads? • Can I get 10 heads?

  14. Boy or Girl? 50/50 • Each time a couple mates there is a 50/50 chance of getting a boy or a girl. • If the same couple has 10 kids what are they most likely to have? • 5 boys and 5 girls • Is it possible to have 10 boys? • Yes • Is it likely? • No

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