History of discovery of genetic code

 HISTORY OF THE DISCOVERY OF DNA

The importance of the discovery of deoxyribonucleic acid (DNA) changed the way of understanding genetics, and the study of how physical and physiological inheritance is transmitted from generation to generation.

In the second half of the 19th century, the DNA molecule was identified for the first time.

In the middle of the 20th century, almost a century later, the structure and functioning of the genetic code was defined, beginning the golden age of discovery in genetics.

In 1869, DNA was isolated for the first time by the Swiss biologist Johan Friedrich Miescher. While studying the chemical composition of white blood cells, he observed that within the cells there was an isolated substance rich in phosphates, without sulfur and resistant to proteases, something that did not correspond to the typical structure of lipids or proteins. He called this new molecule nuclein, since it was found in the nucleus of all cells.

Between 1885 and 1901, the chemical composition of DNA began to be defined.

In 1889 Richard Altmann, a German pathologist who had been a disciple of Miescher, redefined this substance with the term "nucleic acid."

The German physician Albert Kossel discovered the existence of carbohydrates and nitrogenous compounds or bases that he called "adenine", "guanine", "cytosine" and "thymine" within the DNA molecule. This discovery earned him the Nobel Prize in Medicine in 1910.

During the 1920s, the Russian-American biochemist Phoebus Levene determined the existence of RNA, another nucleic acid necessary for the transmission of genetic information.

Levene also detected the presence of the phosphate group and a type of sugar called ribose, two essential components in the formation of DNA. Later, he discovered that the phosphate group, the sugar, and the nitrogenous bases came together to form nucleotides.

The structure of DNA. Each nucleotic is made up of three units: a sugar molecule called Deoxyribose, a phosphate group and one of four possible nitrogenous compounds called bases: (A) Adenine, (G) Guanine, (T) Thymine and (C) Cytosine.

The studies of the microbiologist Frederick Griffith, the findings of Oswald Avery in 1944 and the experiments of Alfred Hershey and Martha Chase in 1952. During the following years, several experiments were carried out that concluded that DNA was the molecule responsible for inheritance.

In 1953, when physicist Francis Crick and biologist James Watson demonstrated the double helix structure of DNA. They received the Nobel Prize in Medicine in 1962 together with the physicist Maurice Wilkins, as it was considered to be one of the most important advances in this field.

However, its discovery would not have been possible without the work of chemist Rosalind Franklin, responsible for the famous Photograph 51 that revealed the helical shape of the DNA molecule. Wilkins, who shared a laboratory with her, took the photograph of her without her permission and thanks to that they made the great discovery of her.

Once the shape and composition of DNA has been discovered, the most recent studies focus on how it works: seeing what chemical reactions take place inside the cell to try to reproduce them in the laboratory.

In this way, gene editing techniques aim to modify the genetic code of some cells whose DNA is incorrect or damaged, which can cause disorders and diseases.

Today, scientists are focused on investigating how to edit DNA to correct mistakes and cure diseases of genetic origin.