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We use…

So far, we’ve been looking at single traits…but what if Patrick married and wanted to know the probability of having offspring that were pink AND had large eyes? How do we figure this out?. We use…. Dihybrid Punnett Squares. Dihybrid Punnett Squares. Defined : Crossing of two traits

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We use…

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  1. So far, we’ve been looking at single traits…but what if Patrick married and wanted to know the probability of having offspring that were pink AND had large eyes? How do we figure this out? We use… DihybridPunnett Squares

  2. Dihybrid Punnett Squares • Defined: Crossing of two traits • 16 possible outcomes • Use the “FOIL” method from math F = First O = Outer I = Inner L = Last • Tips: • Place capital letters first • 2) Group the same letters together

  3. First, we have to figure out all possible gamete combinations (using that FOIL method). • For example: Patrick is heterozygous for his pink body color but is purebred dominant for having round eyes. What is the genotype for his body color? Pp What is the genotype for his round eyes? RR Together, this is PpRR. Now, lets figure out the possible gamete combinations P p R R So, the possible gamete combinations are: PR, PR, pR, pR

  4. Now, let’s do the same for Patrick’s new lady, Patti • For example: Patti is homozygous recessive for her yellow body, but is heterozygous for her roundeyes. What is the genotype for her body color? pp What is the genotype for his round eyes? Rr Together, this is ppRr. Now, lets figure out the possible gamete combinations p p R r So, the possible gamete combinations are: pR, pr pR, pr

  5. We put gamete combos on axis and fill in: PR PR pR pR PpRR PpRR ppRR ppRR pR PpRr ppRr ppRr pr PpRr pR PpRR PpRR ppRR ppRR PpRr ppRr ppRr pr PpRr Ta-Daa!!!! 

  6. Key: R = Round Y = yellow r = wrinkled y = green • Cross two heterozygous dominant Round, Yellow seeds with each other. R r Y y x R r Y y RY Ry rY ry RY RrYy RrYY RRYY RRYy Ry Rryy RRYy RRyy RrYy rY RrYY RrYy rrYY rrYy RrYy ry Rryy rrYy rryy

  7. R = Round r = wrinkled Y = Yellow y = green List all the Possible Genotypes: List all the Possible Phenotypes: 1 RRYY 4 RrYy 1 rrYY 9 Round, Yellow Seeds 2 RRYy 1 RRyy 2 rrYy 3 Round, Green Seeds 2 RrYY 2 Rryy 1 rryy 3 Wrinkled, Yellow 1 Wrinkled, Green

  8. What is the probability of getting: Competely homozygous recessive seed? 1/16th Completely heterozygous plants? 4/16th Homozygous round seeds? 4/16th What is the probability of getting: Wrinkled, yellow seeds? 3/16th Green seeds? 4/16th Three round, yellow seeds? 9/16 x 9/16 x 9/16 = 729/4096 or 17.8% Genotypes: Phenotypes: 1 RRYY 4 RrYy 1 rrYY 9 Round, Yellow Seeds 2 RRYy 1 RRyy 2 rrYy 3 Round, Green Seeds 2 RrYY 2 Rryy 1 rryy 3 Wrinkled, Yellow 1 Wrinkled, Green

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