Chromosome theory of inheritance

William Sutton and Theodor Boveri proposed the chromosome theory of inheritance, the idea that genes are part of chromosomes. It was postulated independently in 1902 that genetic information is carried by chromosomes.
 
It is a set of primary tenets relating to the transmission of hereditary characteristics from parent organisms to their offspring. They were initially derived from the work of Gregor Mendel published in 1865 and 1866 which was "re-discovered" in 1900, and were initially very controversial. Then they were integrated with the chromosome theory of inheritance by Thomas Hunt Morgan in 1915.
 
The studies are based on the experimental crosses of Mendel and the microscopic observations of the mitosis and meosis.
 
Boveri recognized the Mendelian concepts of segregation and assortment could be interpreted to operate on a cellular level, with chromosomes containing the "factors"—as Mendel called the genes. The probability was extraordinarily high, that the characters dealt with in Mendelian experiments are truly connected to specific chromosomes.
 
Sutton, working with marine life forms, had also become familiar with the process of "reduction division" called meiosis, which gives rise to reproductive germ cells, or gametes. In meiosis, the number of chromosomes is reduced by half in sperm and egg cells, with the original number restored in the zygote, or fertilized egg, during reproduction. This process was harmonic with Mendel's idea of segregation. In 1902 Sutton suggested that "the association of paternal and maternal chromosomes in pairs and their subsequent separation during the reduction division...may constitute the physical basis of the Mendelian law of heredity.

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