Dihybrid Crosses Multitrait inheritance Mendels further experiments Mendels

Dihybrid Crosses Multi-trait inheritance

Mendel’s further experiments �Mendel’s monohybrid crosses were based on one characteristic controlled by one gene such as seed shape (round or wrinkled) in a pea plant. �He then went on to ask: “What happens when more than one characteristic is involved in a cross? ”

Crossing two traits �He focused on two characteristics: �Seed shape - (Round - R, and Wrinkled – r) �Seed colour - (Yellow - Y, and Green - y) �He crosses two plants that were heterozygous for seed shape (Rr) and seed colour (Yy) in what we now know as a Dihybrid Cross.

P generation �The first figure shows a cross between to homozygous parent plants that produce plants that are heterozygous for these two traits. Rr. Yy

Possible Combinations �A heterozygous individual for two characteristics will produce four possible gametes. R r Y y RY Ry r. Y ry

The Law of Independent Assortment �Each allele is independent of the other and no two alleles are linked. �In other words, the inheritance of seed shape has no influence on the inheritance of seed colour. �A dihybryd cross can be treated as two separate monohybrid crosses.