Monohybrid Crosses

What is a monohybrid cross? A cross between individuals that involves one trait A Punnett Square is a diagram used to show the probability that certain traits will be inherited by the offspring

Homozygous X Homozygous Dominant crossed with recessive All offspring are heterozygous 100% probability

Homozygous X Heterozygous Dominant crossed with heterozygous 50% dominant 50% heterozygous Recessive crossed with heterozygous 50% recessive

Heterozygous X Heterozygous Probabilities 25% dominant 50% heterozygous 25% recessive

Genotypic Ratio .vs Phenotypic Ratios Using the heterozygous cross: Genotypic Ratio = GG:Gg:gg 1:2:1 Phenotypic Ratio = Green:White 3:1

Test Cross When a dominant phenotype is observed and you want to know the genotype you perform a test cross Cross the individual in question with one that is recessive Ratio of offspring will tell you the genotype

Incomplete Dominance Two or more alleles influence the phenotype Result is an intermediate phenotype

Co-Dominance Both alleles for a gene are expressed in a heterozygous offspring kb24