How Many Types Of DNA?

The DNA molecule which was described by Crick and Watson in the year 1953 was in the B form. There are basically four types of DNA molecules. DNA molecules exist in the A, B, C and Z forms. The primary distinction between all these forms of DNA molecules is the direction in which the helix spirals. In the first three forms of DNA molecules, namely the A, B and C forms of DNA molecules, the helix spirals in the right direction and in the Z form of DNA molecules, the helix spirals in the left direction.

Therefore, the A, B and C forms of DNA molecules are known as right-handed helixes. On the other hand, the Z form of DNA molecules is known as a left-handed helix. The B form of DNA molecules is the major one that is present in the cells of the human body. The Z form of DNA molecules is predominantly found in-vitro under high salt conditions. The cellular environment is basically an environment which has a low-salt condition.