Punnett Squares Predicting the Probability of Inherited Traits.
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Transcript of Punnett Squares Predicting the Probability of Inherited Traits.
Punnett Squares
Predicting the Probability of Inherited Traits
Probability: the likelihood that a particular event will occur
Consider a coin flip: There are two possible outcomes (head
or tails) The chance (or probability) of either
outcome (heads or tails) is equal The probability that a single coin flip will
be heads is 1 chance in 2 possibilities. 1/2 = 50% of flipping a heads or tails
Punnett Square: a tool to predict the probability of inheriting a specific trait.
Mendel’s first generation cross: homozygous purple (PP) X purebred white (pp)1. Draw a box:2. Mom’s alleles --> P P3. Dad’s alleles --> p
p
4. Fill in the boxes5. Offspring genotype- 100% Pp6. Offspring phenotype - 100% purple
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Pp Pp
Pp Pp
Heterozygous (Pp) X Heterozygous (Pp) P p
P
p
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X
PP Pp
Pp pp
Offspring Genotypes:1 PP: 2Pp: 1pp
Offspring Phenotypes:3 Purple: 1 White
Genotypic Ratio: The probability of having each Genotype. 1:2:1 = 25% chance of PP, 50% chance of Pp, 25% pp
Phenotypic Ratio: The probability of having each phenotype.3:1= 75% chance of being purple, 25% chance of being white