Theory of inheritance based on Mendel’s laws.
The term applied to a law enunciated by G. J. Mendel that the offspring is not intermediate in type between its parents, but that the type of one or other parent is predominant. Characteristics are classed as either dominant or recessive. The offspring of the first generation tend to inherit the dominant characteristics, whilst the recessive characteristics remain latent and appear in some of the offspring of the second generation. If individuals possessing recessive characters unite, recessive characters then become dominant characters in succeeding generations.
The laws of inheritance propounded by the Bohemian monk Mendel. An offspring inherits from his parents characteristics not as a blending of qualities from both of them but as separate units. Traits are described as either dominant or recessive. For example, brown eyes are dominant and blue eyes are recessive. If the two genes inherited, one each from each parent, are both dominant, the offspring will have brown eyes and will be pure for brown; if the two genes are brown and blue, the offspring will again be brown-eyed and will be hybrid for brown; and if the two genes are blue, the offspring will be blueeyed. The above example illustrates the Law of Dominance. In the plant world, red is dominant to white in sweet pea flowers. If a red flower is crossed with a white flower, all the first generation will be red-flowered, but hybrids for red. However, if these red hybrid flowers are self-fertilized, then the next generation will produce red flowers in the ratio of three to one.0 The union of the genes in the hybrid red flowers was only temporary, and when sperms and eggs are produced they are either carrying the gene for red color or for white color. This is called the Law of the Purity of Gametes. This separation of traits in the gametes and a new combination of traits in the next generation illustrates the Law of Segregation. There are some exceptions where the Law of Dominance does not operate.