Dihybrid Crosses By the end of today you should be able to: Use the Punnettsqaure method to solve basic dihybrid cross problems
After crossing pea plants with one characteristic; Mendel wondered what would happen if more than one pair of characteristics were cross-fertilized. • For example, what would happen if a round yellow pea was cross-fertilized with a wrinkled green pea?
Mendel wanted to know if a gamete’s allele for the gene encoding pea colour would affect the allele for pea shape. • Do you think one trait has an influence over another trait? Why or Why not?
Mendel, created purebred round yellow peas, which can be represented by the genotype: RRYY • He also created purebred wrinkled green peas, represented by the genotype: rryy • He then cross fertilized these peas RRYY x rryy and recorded his observations. • What do you think the phenotype of the F1 generation was? Why do you think this?
All the resultant offspring were round yellow peas, with the genotype of RrYy. • How do we know that?
Mendel’s 2nd Law • The Law of Independent Assortment: when two or more pairs of characteristics are considered at one time, each pair shows dominance and segregation, independently of each other.
http://188.8.131.52/bio/activelearner/10/ch10summary.html • This website details dihybrid crosses quite nicely. It also has a quiz so you can check your understanding of dihybrid cross problems