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Genetics and Heredity

Explore the fascinating world of genetics and heredity, where inherited traits like eye color, height, and even personality arise. This overview draws on Gregor Mendel's pioneering work, explaining concepts such as allele combinations (homozygous and heterozygous) and genotypic and phenotypic ratios. Delve into the probability of specific traits appearing in offspring, including monohybrid and dihybrid crosses. This guide will answer the common questions about why we inherit traits differently from our siblings, illuminating the principles of genetic inheritance.

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Genetics and Heredity

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  1. Genetics and Heredity

  2. Are these inherited traits? • The color of your eyes • Your height • Your hair color and texture • Your personality • Your musical, athletic, artistic abilities

  3. Think about this…. • “My parents have brown eyes, why are mine blue?” • “My brother is tall. Why am I short?” • “Why does my sister have blonde hair while mine is brown?”

  4. Those were questions that Gregor Mendel tried to answer… • Born in 1822 in Austria • 1843 – Studied Theology • 1846-Studied Science at the University of Vienna

  5. Mendel’s studies led to: Genotype Homozygous (Pure) Dominant HH Hh Heterozygous (Hybrid) Homozygous (Pure) Recessive hh Genotypic Ratio:

  6. Mendel’s studies led to: Phenotype Homozygous (Pure) Dominant Dominant Heterozygous (Hybrid) Dominant Homozygous (Pure) Recessive Recessive Phenotypic Ratio:

  7. PREDICTING HEREDITY The likelihood that a specific event will occur

  8. Probability • Probability = # of 1 kind of possible outcome Total number of possible outcomes • Example: What is the probability that a tossed coin will be heads? • ½ or 50%

  9. Probability • What is the probability that a couple will have four boys? • ½ x ½ x ½ x ½ = 1/16 • What is the probability you will win the lottery? • 6/50 x 5/49 x 4/48 x 3/47 x 2/46 x 1/45

  10. Monohybrid Cross: a cross that shows the possible offspring for one trait

  11. F F f f Ff Ff Ff Ff Probability of having a child with freckles? 100%

  12. F F F f FF FF Ff Ff Genotypic Ratio Phenotypic Ratio 2:2:0 4:0

  13. f f F f Ff Ff ff ff Pure Dominant: 0% Pure Recessive: 50% Hybrid: 50%

  14. Dihybrid Cross: a cross that shows the possible offspring for two traits

  15. d D f f D d f f d F FfDd Ffdd FfDd Ffdd d f ffDd ffdd ffDd ffdd d F FfDd Ffdd FfDd Ffdd d f ffDd ffdd ffDd ffdd

  16. fD fd fD fd Fd FfDd Ffdd FfDd Ffdd fd ffDd ffdd ffDd ffdd Fd FfDd Ffdd FfDd Ffdd fd ffDd ffdd ffDd ffdd Child with dimples? 50% (8/16) Child with freckles? 50% (8/16) Child with dimples and freckles? 25% (4/16)

  17. d D F f d D F f d f FfDd ffdd Ffdd ffDd d f FfDd ffdd Ffdd ffDd d f FfDd ffdd Ffdd ffDd d f FfDd ffdd Ffdd ffDd

  18. FD fd Fd fD fd FfDd ffdd Ffdd ffDd fd FfDd ffdd Ffdd ffDd fd FfDd ffdd Ffdd ffDd fd ffDd ffdd Ffdd ffDd Child with dimples? 50% (8/16) Child with freckles? 50% (8/16) Child with dimples and freckles? 25% (4/16)

  19. FD fd Fd fD fd FfDd ffdd Ffdd ffDd fd FfDd ffdd Ffdd ffDd fd FfDd ffdd Ffdd ffDd fd ffDd ffdd Ffdd ffDd Phenotypic Ratio for freckles? 1:1 Phenotypic Ratio for dimples? 1:1

  20. Monohybrid (and Dihybrid) Practice You must do this individually and turn in for a daily grade

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