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Probability and P unnett Square

Probability and P unnett Square. Probability: likelihood that a specific event will occur. Principle of probability: used to predict the outcomes of genetic crosses. Two important points to remember with

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Probability and P unnett Square

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  1. Probability and Punnett Square

  2. Probability: likelihood that a specific event will occur. Principle of probability: used to predict the outcomes of genetic crosses.

  3. Two important points to remember with probabilities: Past outcomes do not affect future events Probabilities predict the average outcome of many events

  4. Punnett Squares: diagrams that model genetic crosses. can be used to predict and compare the genetic variations that will result from a cross.

  5. Homozygous: Organisms that have two identical alleles for a particular trait—TT,tt Heterozygous: Organisms that have two different alleles for the same trait--Tt

  6. female gametes B b B b male gametes Monohybrid Crosses Cross two Alaskan huskies that areheterozygousforbrown eyes (Bb). STEP  BB = brown eyes Bb = brown eyes bb = blue eyes Genotypes % 25% BB, 50% Bb, 25% bb Ratios 1BB:2Bb:1bb STEP  BB Bb Cross Bb x Bb STEP  STEP  Bb bb Phenotypes % 75% Brown eyed, 25% Blue eyed Ratio 3 Brown eyed: 1 Blue eyed

  7. RG Rg rG rg DIHYBRID CROSSES Cross: RrGg X RrGg EXTRA STEP - Finding the possible gametes STEP  (R r) (Gg) • F.O.I.L • First • Outer • Inner • Last

  8. Incomplete Dominance • In incomplete dominance, neither allele is Dominant-blending of traits when two different alleles for the same trait occur together. • Colors blend together • heterozygous individuals = 3rd phenotype red pink white

  9. Incomplete Dominance • Four O’ Clocks, if you cross a red RR(which is always pure) with a white WW (that is also always pure) , you get a pink RW(which is always hybrid / heterozygous RW RW RW RW

  10. Incomplete Dominance • In another flower, if red RR and blue BB flowers are crossed, they produce a 3rd purple RB flower • What would be the genotype ratio and phenotype ratio if you crossed two purple flowers?

  11. Cross of two purple flowersRB X RB • What are gamete possibilities? • genotype ratio • phenotype ratio • Can you have a heterozygous red orhybrid blue flower? R B RR RB R red purple BB RB B purple blue

  12. Codominance • Both alleles contribute to the phenotype of the organism by showing up simultaneously (at the same time) in heterozygous individuals. • In cattle and horses, if you cross a pure red (RR) with a pure white (WW), you get (RW) which produces the color roan.

  13. Codominance • These cattle or horses actually have both red and white hairs intermixed, or are spotted. Roan is a third phenotype. • If you cross a roan with a white… R W RW WW W roan white RW WW W roan white

  14. Codominance • Andalusian chickens also show this pattern of inheritance. • If you cross a black (BB) chicken • With a white (WW) chicken • You get black+white speckled (BW) chicken

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