Monohybrid Cross Experiment Outline

This experiment is called a monohybrid cross because Dr. Specht was tracking the inheritance of one trait that differed between the parents that were crossed. His monohybrid cross experiment was carried out as follows:

1) Cross a mutant plant with a truebreeding normal plant using the normal plant as the pollen donor. The seed produced is called F1 seed (first filial or first family generation). Repeat this using the mutant as the male. This is the reciprocal cross. Again F1 seed were produced, but kept separate from the first cross.

2) Plant the F1 seed and observe the phenotype. Allow the plants to self-pollinate to produced F2 seed. Harvest the seeds from an individual plant and place into a labeled envelope. Do the same with the reciprocal cross.

True breeding parents are crossed to make F1s. F1s are selfed to make F2s. (Image by P. Hain)

3) Plant the F2 seeds from each envelope into a separate row. Observe and record the phenotypes of plants in each row. Allow the plants to self-pollinate to produce F3 seed.

4) Harvest the F3 seed from each plant; place in a labeled envelope and record in the computer the phenotype of the parent for each envelope.

5) Plant the F3 seed in progeny rows. Walk the rows (lots of rows in this generation!), score and record the phenotypes observed in each row.

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