The most haunting enigma in the history of the human body is why we are what we are. In this chapter, we will attempt to answer that question.
When a new individual is conceived, two sex cells (haploid cells), in other words, a sperm from a man and an ovum from a woman, unite to produce a single fertilized cell (diploid cell).
This cell contains all of the information needed to create a new human being with its own traits, such as, hair color, blood type, metabolism and intellectual and artistic skills.
We inherit this information from our parents and it is stored within our genes in code form within a molecule called deoxyribonucleic acid (DNA). Other characteristics not inherited from our parents are also stored here, those are called variations.
This means that human inheritance is made up of the similar traits passed on between parents and children and the variation are the non-similar traits.
The latter are genetically transferred or are a product of the environment.
Therefore, inheritance and variation constitute the base of genetics, one of the most important scientific fields of the century.
History of the hereditary mechanism
In the late XIX century, there was little knowledge regarding the transmission of one generation’s characteristics to another. This went for plants as well as animals and human beings.
Gregor Mendel’s work and the subsequent contributions made by molecular genetics helped solve these questions. Mendel’s research consisted of cross-pollinating pure strains of pea plants. A pure strain means plants that spawn identical plants if they pollinate another of the same strain.
Mendel obtained seven traits: pea texture (smooth or wrinkled), pod color (yellow or green), flower color (purple or white), pea shape (round or wrinkled), pea color (green or yellow), flower position (axial or terminal) and plant size (normal or small).
This way, he compiled a considerable amount of data, which he used to construct charts to analyze probabilities.
Today, his invaluable conclusions are known as the Mendelian laws of inheritance.
