Question

How are deviations from Mendel’s law of inheritance explained?

Answer 1

Gregor Johann Mendel proposed the law of inheritance or Mendel’s law of inheritance after conducting several experiments on the garden pea plants. This includes three laws that are the law of dominance, the law of segregation and the law of independent assortment.

Complete answer:
There are more and more studies and discoveries were made on genetics after Mendel’s studies. He said that the regularities of his experiment are applied only to the organisms he consciously chose for his experiments. Gregor Mendel explained the inheritance in terms of a discrete unit called factors or genes. According to the rules of probability, these genes are passed from generation to generation. The Mendel’s laws apply to the organisms that are reproduced sexually including human and garden pea plants. This law is not explaining in some pattern of genetic inheritance. Apart from his laws, there are several deviations from Mendel’s law of inheritance they are as follows:
-Incomplete dominance: In this phenomenon, none of the two alleles of a gene was dominant over each other. Both of the alleles are present together and new phenotype is produced. The new phenotype is somewhat intermediate to the original one.
-Co-dominance: This is a phenomenon where both the alleles express themselves simultaneously in a heterozygote.
-Polygenic inheritance: It has occurred when one character is controlled by more than one gene.
-Multiple alleles: When three or more than three alleles occur for a particular gene or occupying the same locus are called multiple alleles.
-Pleiotropy: This condition occurred when one gene influences two or more phenotypic traits.

Note: The scientist Gregor Johann Mendel is the founder and also called the father of genetics. He conducted many experiments on Pisum sativum (pea plants) plants for seven years (1856 to 1863). He chose the pea plant only because:
-Pea plants can easily grow and are easy to maintain.
-Pea plants have several distinct and contrasting traits.
-It is an annual plant therefore many generations can be studied in a short period.
-They are self-pollinating but can be cross-pollinated.