#Mendel: Laws of Inheritance

Before the 1860s, the prevailing view of heredity was 'blending inheritance,' where traits of parents were thought to mix like paint. Gregor Mendel’s 1866 paper on pea plant experiments systematically dismantled this idea. By tracking specific, discrete traits over generations, Mendel observed that inheritance is not a continuous blend but a transmission of distinct units. He found that traits could disappear in one generation and reappear in the next, suggesting that the underlying 'factors' of inheritance remain intact even when they are not visible.

#Particulate Inheritance

A Punnett square (introduced later) illustrating Mendel's predictable 3:1 ratio of inheritance.

Mendel’s primary observation was that traits like seed shape or flower color are governed by pairs of discrete units, which we now call genes. In his crosses, a plant with round seeds bred with a plant with wrinkled seeds did not produce semi-wrinkled seeds; it produced only round seeds. In the subsequent generation, the wrinkled trait reappeared in a predictable 3:1 ratio. This result suggested that some traits are dominant and others are recessive, but both are carried as distinct 'particles' rather than being diluted through mixing.