Inheritance and Probability

Gregor Mendel, an Austrian monk, is most famous in this field for his study of the phenotype of pea plants, including the shape of the peas on the pea plants.

Gregor Mendel’s Work

Mendel’s goal was to have a firm scientific basis on the relationship of genetic information passed on from parents to offspring. In light of this, he focused on how plant offspring acquired the phenotype of their seeds. In this example, there are two choices, round and wrinkled seeds.

The plants that were used in the experiment had to be true breeding, i.e. those plants with round seeds must have had parents with round seeds, who in turn had parents producing round seeds, etc. This is done to increase the accuracy of the results.

After successfully producing two generations from these true-breeding plants, the following was evident

Mendel successfully hypothesized that the reason for this trend in phenotypes from generation to generation was down to the fact that genetic information was being passed on from their parents.

The fact that round seeds appeared more frequently than wrinkled seeds is due to round seeds being the dominant phenotype, which when present effectively ‘masks’ the phenotype of the recessive (wrinkled seed) gene.

Dominant and Recessive Alleles

The parents, one possessing wrinkled seeds the other possessing round were crossed together, for some reason in the first and second generation the presence of the round seed gene in offspring superseded the presence of the wrinkled seed. This is called dominance.

The next tutorial presents Gregor Mendel’s law of dominance. Learn more about this form of inheritance and how it can be predicted using a Punnett square