Chromosome Number in Humans

The Purpose of Sex.

Scientifically, sex has a single purpose: to pass on one's genes to a new generation. The genes are part of the DNA molecules, the basis of heredity within each cell. In turn, the DNA is packaged into structures called chromosomes. Every species of animal and plant has a certain number of such chromosomes within each of its cells. Remarkably, it was not until 1956 that the number of human chromosomes was correctly determined.

Background.

In 1865 Gregor Mendel published his famous work on genetics in which he used garden peas in his experiments. Mendel showed that certain characteristics of the peas were inherited in predictable ways. Some traits were dominant and others recessive. If two pea plants are crossed, for example, one might have a dominant trait that determines the shape of the pea while the other might have a recessive trait that calls for a different shape. When these two are crossed,...

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