561880-3-26P AID: 2975 | 19/03/2013
RID: 2498 | 07/05/2013
RID1: 40621 | 07/04/2017
If independent assortment of all genes occurs, the number of phenotypic classes and the number of genotypic classes can be determined. With the assumptions of independent assortment and simple-dominant recessive relations of all genes, the number of genotypic classes expected from a heterozygous plant for n gene pairs is 3n and the number of phenotypic classes expected is 2n.
| Number of genes | Number of genotypes | Number of phenotypes |
| 1 | 3 | 2 |
| 2 | 9 | 4 |
| 3 | 27 | 8 |
We can write 3, 9 and 27 as 31, 32, and 33. The values of 2, 4 and 8 can be written as 21, 22, and 23. When a plant heterozygous for n gene pairs is selfed, we can obtain the number of genotypes and number of phenotypes by using this simple formula:
For genotypes: 3n where n is the number of genes
For phenotypes: 2n where n is the number of genes