Mendel's laws and genetics

Mendel's laws and genetics

Gregor Mendel was a modest Augustinian monk from the Abbey of Brno (or Brünn), who never imagined that he would go down in History as the father of Genetics.

Concerned about improving the crops of the monastery garden, he decided to conduct an experiment. He took some seeds of a variety of pea that the monks cultivated in his garden. The pea pisum sativum, which gave green or yellow seeds. He crossed the seeds together, and observed the results. He embodied the conclusions of his experiment in three simple laws.

To begin, he took only the pure races. Pure yellow seeds produced other yellow seeds, and pure green ones produced other green ones. But what happened when crossing a pure yellow seed with a pure green one?

He obtained a hybrid seed, not pure. In the first generation, all hybrid seeds were born yellow. All inherited the character of the yellow parent. He called it dominant. But they also had a green parent, whose character they did not manifest. He called it recessive. Mendel's first law is the law of uniformity: all first-generation descendants are equal to each other and equal to one of their parents.

He crossed them again to get a second generation. Now, three out of four seeds were yellow and one green. The recessive character that did not manifest itself in the first generation now appeared. I deduce Mendel's second lay or segregation law: when crossing hybrids in second generation, the characters are separated and randomly combined. Mendel gave his laws a mathematical approach, so he applied the rules of probability to predict the results in each generation.

The experiment was clear taking only the color character. But is there a relationship between different characters? For example, color, shape, texture ... To find out, he crossed smooth yellow peas with rough greens. He obtained a first generation of smooth yellow seeds. The smooth character was dominant, and the rugged recessive. In the second generation, however, all combinations appeared. Thus, Mendel's third law is the law of independent inheritance of characters: characters are inherited independently of each other and randomly combined in the offspring.

Mendel published his laws in 1865, but they barely spread. His work was not known until thirty years later. Independently, other biologists came to the same conclusions and recognized the merit. Although today we know that his laws are only valid in certain cases (he was lucky to choose that pea variety).

That was how, long before the genes and DNA were discovered, an Augustinian monk who only wanted to improve his garden, established the basis of Genetics, one of the most important sciences today.

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