Inheritance of pod colour in peas

Monohybrid inheritance is the inheritance of a single gene. To take a simple example we will look at one of the features Gregor Mendel studied-the colour of the pods of pea plants. Pea pods come in two basic colours-green and yellow. If pea plants with green pods are bred repeatedly with each other so that they consistently give rise to plants with green pods, they are said to be pure-breeding for the character of green pods. Pure-breeding strains can be bred for almost any character. This means that the organisms are homozygous (that is, they have two alleles that are the same) for that particular gene. If these pure-breeding green-pod plants are then crossed with pure-breeding yellow-pod plants, all the offspring, known as the first filial, or F,, generation, produce green pods. This means that the allele for green pods is dominant to the allele for yellow pods, which is therefore recessive. These observed facts led to the formation of a basic law of genetics (the law of segregation). This states, In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete.