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Pedigrees

Pedigrees. Aa. Aa. aa. Aa. Aa. aa. aa. AA or Aa. aa. aa. aa. Recessive Pedigree. Multiple Gene Inheritance. With a fancy background. warmup. What are the odds of rolling a 6 on a die and pulling an Ace out of a standard deck of 52 cards?

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Pedigrees

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  1. Pedigrees Aa Aa aa Aa Aa aa aa AA or Aa aa aa aa

  2. Recessive Pedigree

  3. Multiple Gene Inheritance With a fancy background

  4. warmup • What are the odds of rolling a 6 on a die and pulling an Ace out of a standard deck of 52 cards? • What are the odds of rolling a 6 on a die OR pulling an Ace out of a standard deck of 52 cards? • What are the odds of rolling two die and having a total of 12? • What are the odds of rolling two die and having a total of 11?

  5. When multiple Genes Are Inherited • They are inherited independently of each other* • *with one major exception • So we can muse multiplication and addition rules the same way you did on the warmups

  6. Practice • What are the odds that two parents with the genotype AaBb mate and have children that express the dominant phenotype in both traits?

  7. More Practice • If an AaBbDd parent mates with an AAbbDd parent, what are the odds the offspring will have the genotype AABbdd?

  8. Slightly Harder Practice • An AabbDd man and a aaBbDd woman mate. What are the odds they have a child with the same genotype as either one of them?

  9. Other Way To solve • Draw a cross of all the possible sperm x all the possible eggs • Draw a cross for AaBb x AaBb

  10. Example – Blood Types • IA, IB dominant to I • + dominant to – (++ or +- will exhibit + blood) • If an individual with AB- blood mates with someone with BO+- blood, what are the odds they have a child with A+ blood

  11. What 2 parents could produce a child with every possible blood type? Show the cross

  12. Example – Eye Color • For the most part, eye color is controlled by 2 genes on separate chromosomes • In gene 1 brown is dominant to not brown. If the offspring has the brown allele the second gene is irrelevant • In gene 2 green is dominant to blue. This only matters if the individual is bb in the first gene

  13. Eye Color Practice • Two BbGg parents mate. What are the odds their offspring have each of the possible eye colors?

  14. *Note on Eye Color • This explains the majority of eye inheritance but it is an incomplete explanation • For some reason that geneticists haven’t figured out sometimes two blue eyed parents have offspring with other color in the eyes – IT DOESN’T MEAN YOU WERE ADOPTED OR YOUR MOM CHEATED ON YOUR DAD • Probably another gene affects eye color a bit – (e.g. hazel eyes, blueish greenish eyes, how dark/light the color is etc.)

  15. Epistasis • Often times one gene acts as a switch for whether or not another gene can get expressed or not • Simplest example: • In mice, black fur color is dominant to agouti (brown) • BUT this color gene only gets expressed if another gene (the color gene) is active. Color (C) is dominant to no color (c)

  16. Epistasis practice • If two BbCc mice mate, what are the odds of having a child that is agouti?

  17. So Why Is it hard to Track Many Traits like heart disease or cancer? • Many genes are involved, some directly, some via epistasis • So it’s trying to figure out a gene that affects a gene that affects another gene that affects another gene • The environment has a huge effect on activating or deactivating expression of some genes

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