DNA

 DNA

In 1910, Thomas Morgan discovered that genes are located inside chromosomes, Later on, in 1944, Oswald Avery, Collin McLeod and Maclym McCarty proved that chromosonmes are made up of DNA and not protein, which is what was previously bilieved.

Nowadays we know that genes contain essential biologocial information and that this is why they are locatd inside all cells. We also know each gene in made up of one DNA molecule, which provides the cell and the organism with its biological characteristics. As DNA defines an organism, it is considered the most fundamental biological molecule.

Molecular structure

DNA molecules are doubles-stranded, as two polynucleotide chains form then, the two strands are connected because the complementary nitrogenous bases are linked together by a hydrogen bond.

In DNA molecules, adenaine (A) and Thymine (T), as well as  guanine (G) and cytosine (C), always join together. They are complementary. This way the distance between the pairs of strands is always the same.

The resulting structure looks like a rope ladder that wraps around itself. Each of the steps represents the link between the nitrogenous bases.

In 1953, James Watson and Francis Crick created a doublé-stranded model tranks to Rosalind Franklins´s DNA studies using X-ray diffraction.