# DIHYBRID PUNNETT SQUARES How to predict offspring using

DIHYBRID PUNNETT SQUARES! How to predict offspring using the dihybrid squares

REMINDER: MONOHYBRID PUNNETT SQUARES Looking time. at ONE trait at a

DIHYBRID PUNNETT SQUARES Looks at TWO traits at once! Gametes are still located at the top and left side of the square. Offspring possibilities are written inside the boxes but both genotypes are written together (Ex. Tt. Pp)

STEPS FOR A DIHYBRID: TWO TRAITS AT A TIME 1. Figure out the genotypes for each parent. RRTt x Rr. Tt Dad mom 2. FOIL the genotypes for each parent SEPERATELY: Dad Mom First ----- RT ------- RT Outer ----- Rt ------- Rt Inner ----- RT ------- r. T Last ----- Rt ------- rt 3. Place the new FOILed genotypes in the square

First parent on top (dad), second on left (mom) 4. Complete the Punnett square with the offspring alleles. 5. Figure out the genotype and phenotype results. RT Rt RT RT RT RRTt RRTT Rt RRTt RRtt RRTt r. T Rr. Tt Rr. TT rt Rr. Tt Rrtt Rr. Tt Can be displayed as: Number 4 Rr. Tt Fraction¼ Rr. Tt (4/16) Percent 25% Rr. Tt

Use the foil method to figure out the mother and father genotypes to be used in the dihybrid crosses: T = tall, t = short and R=right handed, r = left handed TTRr X Ttrr Mom First Outer Inner Last TR Tr Dad Tr Tr tr tr How many offspring will be tall? (fraction) How many will be left-handed? (percent) How many will be tall and right handed? (Fraction) TR Tr Tr TTRr TTrr tr Tt. Rr Ttrr

Use the foil method to figure out the mother and father genotypes to be used in the dihybrid crosses: T = tall, t = short and R=right handed, r = left handed First Outer Inner Last Tt. Rr X Tt. Rr How many offspring will be right handed? (percent) Mom How many will be short and left-handed? (fraction) TR Tr t. R tr Dad TR Tr t. R tr How many will be tall and left-handed? (Fraction) TR Tr t. R tr TR TTRr Tt. RR Tt. Rr Tr TTRr TTrr Tt. Rr Ttrr t. R Tt. Rr tt. RR tt. Rr tr Tt. Rr ttrr Ttrr

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