History of the genetics and molecular biology

The Genetic traditional, known as mendélienne, seemed a Science of the Hérédité . It brought answers on the resemblance parent-descent. This science proposed the concept of Gène : a gene does not exist, it is a concept; in nature there are only Molécule S, this by using the basic methodology of the genetics: the crossing. This technique is not possible that at the species having a sexuality and requiring individuals of different Phénotype. This methodology was installation at the beginning of the 20th century by Mendel thanks to its famous experiments on the garden peas.

Then the scientists were interested in the distribution of genes on a scale a whole population: it is the Génétique populations.

the discovery that the genes are localized on the chromosomes sees the birth of the Cytologie. This projection made it possible to include/understand which was the bond between the cellular division and the transfer of characters to the wire of the generations.

appearance of the Cytogenetic (study of the chromosomes) with license in particular in the mankind the tracking of anomalies at the embryo for example. These projections date from the years 1930.

Then the studies of genetics are directed towards interactions with an incipient discipline, the Biochimie. The researchers understood that the physiological function of genes had something to see with the manufacture of the enzymes.

In the years 1940 one considers that a gene codes a Protéine (enzyme). It was shown that a gene consisted of Nucleic acid. This discovery involved the physical and chemical study of this molecule. One thus could determine the structure of DNA in double helix in 1953. This discovery made it possible to include/understand of what a gene consists and how it could be duplicated to provide an exact copy during the cellular division.

The genetics became a discipline which is interested in the DNA i.e. the molecular Génétique. The molecular genetics was completed with the sequencing of the complete Génome S. This projection allows studies on a all gene scale of a species. When the scale is changed science changes name: one currently speaks about Génomique.

The génomique one introduces new problems to be solved: flow of information contained in the DNA is used by the cell to manufacture its proteins. In genetic terms, the genome of an individual constitutes his genotype. This individual will have a certain appearance (phenotype). Each one of enters develops us several phenotypes: embryo-young person-adult-old man. It is true also on a cellular scale: a muscular cell has the same genotype as a neuron, i.e. for the same genotype one develops several phenotypes. The problem is of knowing how the system is controlled so that this information transferred to proteins will give a certain well defined phenotype. How is the form of genes in such manner controlled to give a nonrandom phenotype?

To answer these questions the researchers have the techniques and methods of the genetics in order to answer controls of the Expression of genes at the eucaryotes.

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