Independent Assortment

• This law states that “when two pairs of traits are combined in a hybrid segregation of one pair of traits is independent to the other pair of traits “.
• The punnett square can be effectively used to understand the independent segregation of the two pairs of factor during meiosis.

Non-Recognition to Mendel’s work

Mendel work remained unnoticed and unappreciated for several years due to following reasons :-

• Communication was not easy in these days and his work could not be easy in these days and his work could not be widely publicised.
• His concepts of stable, unblending discrete units or factors for various traits did not find acceptance from the contemporaries like Charles Darwin etc.
• His approach of using mathematical and statistical analysis to explain biological phenomena was totally new and unacceptable to many of the biologist of that time.
• He could not provide any physical proof for the existence of factors.
• Non discovery of chromosomes, mitosis and meiosis at the time of mendel’s work.
• Mendel died in 1884.

After Mendel’s death :-

• In 1900 three Scientist independentely rediscovered the principles of heredity already worked out by mendel..
• They were De-vries of Holland and Von Tschermak and Carl correns of Germany.
• Also by this time advancement in microscopy that were taking place, scientist were able to carefully observe cell division.
• This led to the discovery of structure in nucleus that appeared to double and divide just before each cell division.
• By 1902, the chromosomes movement during meiosis had been worked out.
• It was found that, there is striking relationship between factors and the chromosomes.

Chromosomal Theory of Inheritance was proposed Independently by Sutton and Boveri

The salient features of chromosomal theory of inheritance are as follow:-

1) Like the heredity traits the chromosomes retain their number, structure and individually throughout the life of an organism and from generation to generation. The two neither get lost nor mixed up.
2) Both chromosomes as well as genes occur in pairs in the somatic or diploid cells.
3) A gamete contains only one chromosomes of a type and only one of the two alleles of a trait.
4) The paired condition of both chromosomes as well as Mendelian factor ris restored during fertilization.