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Dihybrid inheritance is the inheritance of two characteristics that are determined by separate genes. The following example will look at seed colour and texture in pea plants. It is another of Mendel's experiments. The genes in this example are found on different chromosomes so they are said to be unlinked genes.

Example: Seed colour and texture in pea plants

  • Mendel started with pure breeding strains of pea plants. One set of plants had round, green seeds, and the other set of plants had wrinkled yellow seeds.
  • These plants were crossed.
  • All the seeds of the offspring were round and yellow.
  • Mendel determined from these results that the allele for yellow coloured seeds is dominant to the allele for green coloured seeds, and that the allele for round seeds is dominant to the allele for wrinkled seeds.

This is shown in the genetics diagram below.

inheritance
inheritance
  • Mendel then crossed the F1 generation with themselves.
  • The results of this cross were
    • 315 round, yellow seeds
    • 108 round, green seeds
    • 101 wrinkled, yellow seeds
    • 32 wrinkled, green seeds
    • Total = 556 seeds

This is shown in the genetics diagram below.

Figure 9
inheritance
Definitions
									R = allele for round seeds,
									r = allele for wrinkled seeds,
									Y = allele for yellow seeds,
									y = allele for green seeds
inheritance


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