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Asked Mar 14, 2019
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What are the old theories of genetics pangenesis and blending?

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Step 1

Charles Darwin proposed his pangenesis theory in 1868 to describe the units of inheritance between parents and offsprings and the process by which those units control development in offsprings. This theory originated from the claim that the characteristics acquired during an organism's life were heritable. Darwin coined a concept of gemmules, which referred to the minute particles of inheritance that migrated through the body to contribute to that parent's gametes, that is their eggs or sperms. The theory suggested that an organism's environment could modify the gemmules in any parts of the body, and would gather in the reproductive organs of the parents to be passed on to their offsprings.

Darwin's theory of pangenesis lost its popularity in the 1890s when biologists increasingly abondoned the theory of inheritance of acquired characteristics (IAC) on which the pangenesis theory relied. The theory of pangenesis was thus replaced by the germ plasm theory and then afterwards, by the chromosomal theories of inheritance. Similarly, the concept of genes replaced the concept of gemmules.

Step 2

Blending inheritance was a concept that was originally proposed by the biologists in the nineteenth century, including Darwin. This early theory assumed that it is an inheritance in which the characters of the parents appear to blend to form an intermediate state in the offspring, and there is no apparent segregation in later generations. Thu...

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