A botanist has acquired a group of sweet pea plants. All of the plants have yellow pea pods (the recessive trait), except for one, which has green pea pods (the dominant trait). Pea pod color is a trait caused by a single gene. In this tutorial, you will determine how the botanist can identify the genotype of the green pea pod, and how this relates to Mendel's laws and meiosis.

In order to find out the genotype we do a testcross of green pea pods with yellow pea pods.

Explanation:

1. If the F1 generation consist of green pea pods only then the genotype of the green pea pod is 'GG' (i. e the dominant alleles).

TEST CROSS

Green pea pods X Yellow pea pods

GG X gg

Gametes:

G X g

F1 Generation:

Gg

2. However if the F1 generation consist of 50% green pea pods and 50% yellow pea pods then the genotype of green pea pods is 'Gg' (both the dominant and recessive alleles).

Green pea pods X Yellow pea pods

Gg X gg

Gametes:

G g X g

F1 Generation:

Gg, gg

We can relate this to Mendel's Law of segregation and meiosis as

Both the alleles segregate into seperate gametes (i. e they are sorted independent of one another). This segregation is similar to the first division of meiosis in which homologous chromosomes of gene are segregated in daughter nuclei