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Mendel’s laws of inheritance

Dihybrid crosses—two non-linked pair of traits Dihybrid crosses involve alleles for two separate traits that are found on different chromosome. For example, vestigial wings and rosy eyes are mutant recessive alleles found on Chromosome 2 and Chromosome 3, respectively. A typical dihybrid cross could be made by pairing males that were homozygous for vestigial wings and rosy eyes with females that were homozygous wild type for both traits. This would be the P1 generation. The resulting F1 generation would all be heterozygous each trait although wild type in phenotype, as shown by the Punnett square below. Because chromosomes assort independently during meiosis to form gametes, equal numbers of “+ +”, “vg +”, “+ ro”, and “vg ro” allele pairs are expected in the eggs and sperm produced by F1 adults. The F2 generation resulting from pairing F1 males and females would have all possible combinations of the gamete genotypes, as in the following Punnett square: The F2 generation is expected to have a 9 wild type: 3 vestigial-winged: 3 rosy-eyed: 1 vestigial-winged rosy-eyed phenotypic ratio.