3.20: Predict the Probabilities of Outcomes from Monohybrid Crosses

MONOHYBRID CROSSES: Four Possible Outcomes From a Monohybrid Cross Diagram

• Identify the Genotype of Parents from their Phenotype and the Possible Gametes they can Produce

• Insert the Possible Gametes Parents can Produce into a Punnett Square to Find Possible Genotypes of Offspring

• Find the Ratio of the Possible Genotypes and Identify their Phenotypes

EXAMPLE: EYE COLOUR

• B is a Dominant Allele for Brown Eyes

• b is a Recessive Allele for Blue Eyes

EYE COLOUR OF OFFSPRING
PHENOTYPES OF PARENTS	Brown Eyes                         Brown Eyes             (Heterozygous)                    (Heterozygous)
GENOTYPES OF PARENTS	Bb                                          Bb
GAMETES
GENOTYPES OF OFFSPRING
PHENOTYPES OF OFFSPRING
RATIO	Brown Eyes   =    ¾               Blue Eyes      =    ¼