Chromosomal Theory of Hereditary

Chromosomal Theory of Hereditary
Introduction
The chromosomal theory of inheritance was first formulated by the American Biologist “Walter Sutton” in 1902.
Postulates
The main postulates of this theory are as under
i. Hereditary Material
ii. Segregation of Chromosomes
iii. Number of Chromosome
iv. Independent Assortment
i. Hereditary Material
Reproduction involves the initial union of only two cells, egg and sperm If Mendel’s model is correct then these two gametes must make equal hereditary contributions. Sperm, however contains little cytoplasm, therefore the hereditary material must reside within the nuclei of the gametes.
ii. Segregation of Chromosomes
Chromosomes segregated during meiosis in a manner similar to that exhibited by the elements of Mendel’s model.
iii. Number of Chromosome
Gametes have one copy of each pair of homologous chromosomes, diploid individuals have two copies.
iv. Independent Assortment
During meiosis each pair of homologous chromosomes orients on the metaphase plate independent of any other pair.