Each individual is not only psychologically, but also physically and biochemically unique due to his or her genetic information. The basis is formed by the miraculous molecules of deoxyribonucleic acid (DNA).
On the one hand, the DNA is infinitely variable, on the other hand, its structure is firmly defined.
Structure of the DNA
The cell nucleus contains a data set of approx. 3 million information units. They serve as information for the synthesis of biochemical substances. The DNA molecules are rolled up in 46 units, the chromosomes. Individual parts of the DNA chain contain between 50,000 and 100,000 different genes. The DNA molecules are structured in form of double spirals. Each of the tightly wound DNA double spirals contains sugar and phosphate molecules as the outer structure and the 4 nitrogenous bases adenine (A), guanine (G), cytosine (C) and thymine (T) as the inner structure. The entire genetic information is based on the individual sequence of these 4 molecules, which are each arranged as a pair of molecules and bridge the two spiral DNA strands. C is always connected to G, A is always connected to T. Although human genes look similar to some extent, as the same repertoire of proteins is required for many cell functions, there are still individual gene variations over long distances of the double helix.
Renewal
Cells of the human body have 2 x 23 chromosomes, namely 23 chromosomes from each parent. When the cells divide by mitosis, they duplicate exactly their two sets of chromosomes. After division of the DNA strands, the missing halves are immediately built and incorporated into the remaining sequence halves.
Inheritance
To ensure that the human gene pool remains its diversity and does not double with each generation, the cells of the sexual organs are only equipped with half a set of data. Through meiosis, a different type of cell division, egg cells and sperm cells are formed in the ovaries and testicles with only half the genetic material of their original cells. Meiosis ensures the constancy of the hereditary process on the one hand and individual gene selection from one data set from both parents on the other.
Diversity
When the sperm and egg unite during fertilization, an all new composition of 23 chromosome pairs is created, i.e. an embryo with 46 completely new chromosomes.
