Genetic Variation

A scientific explanation

Quote to Prove

"The odds of two people with separate sperm and separate eggs creating organisms that look exactly the same or people that look the same is almost impossible. It's 1 in 70 trillion times that would happen."

-Paul Anderson


Through meiosis, gametes are formed. Different pairs of gametes are formed as shown in the images below. During meiosis different processes allow for tons of different variations. These processes are called crossing over, independent assortment, and random fertilization.

Crossing Over

Crossing over is when genetic material from the two tetrads switch places. One tetrad has a certain amount of the other on it. The other tetrad gets an equal amount of the first tetrad. The amount that crosses over is not set, so different amounts can come from different tetrad sets. This creates more variation helps prove the statistic by showing that tons of possibilities are already created with only one of the ways that the variations are created.

Independant Assortment

Independent assortment is when tetrads line up differently in the original cell. This means that when the cell splits to create other cells, thee tetrads are in a different order than before. When coupled with crossing over even more possibilities are created. Perhaps the possibilities are even doubled (or more).

Random Fertilization

Random Fertilization is when the male's sperm (created during meiosis) fertilizes a female's egg (also from meiosis). The chance of successful fertilization is what makes it random. Even after all the possibilities created with crossing over and independent assortment, what really creates the 1 in 70 trillion odds is that it is pure chance which sperm will meet up with an egg and fertilize.