What is the chromosome theory of inheritance?
The chromosome theory of inheritance holds that genes are carried on chromosomes, which are the physical basis of heredity. My experiments with Drosophila provided the first solid evidence for this. For example, when I crossed white-eyed male flies with red-eyed females, the trait appeared only in males in the second generation—a pattern that matched the inheritance of the X chromosome. I also observed linkage, where certain traits tend to be inherited together because their genes lie close on the same chromosome. Crossing over, the exchange of segments between homologous chromosomes, explained why linkage is not absolute. This is not mere speculation; it is a matter of linkage and crossing over, verified by counting progeny.
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