Why are mycoplasmas classified differently from true bacteria?

Mycoplasmas are classified differently from true bacteria primarily due to their lack of a cell wall. This characteristic is a fundamental distinction that sets mycoplasmas apart from other bacterial organisms. Most bacteria possess a rigid cell wall composed of peptidoglycan, which provides structure and protection. However, mycoplasmas are unique in that they lack this cell wall, making them much more flexible and giving them a different morphology, which often resembles small spheres or filaments.

The absence of a cell wall also has implications for their susceptibility to certain antibiotics, particularly those that target cell wall synthesis, such as penicillin. Since mycoplasmas do not have a cell wall, these antibiotics are ineffective against them.

While mycoplasmas do reproduce via binary fission and contain ribosomes, these features are not unique to them and are common to all bacteria. The idea of having a unique genetic structure is also not solely characteristic of mycoplasmas, as various bacteria can exhibit unique genetic traits. Therefore, the defining factor for their classification is the lack of a cell wall.