The Smallest Cell: Mycoplasma or PPLO?

Introduction:
Mycoplasma and PPLO (Pleuropneumonia-like organisms) are closely related terms and often used interchangeably. Mycoplasma is a genus of bacteria that lack a cell wall, making them the smallest known free-living organisms. PPLO, on the other hand, refers to a group of tiny bacteria-like organisms that were originally thought to cause a specific disease in animals known as pleuropneumonia. However, both terms are now used synonymously to refer to the same group of organisms.

Mycoplasma:
- Mycoplasma are the smallest known cells capable of self-replication.
- They belong to the class Mollicutes and lack a cell wall, which gives them a unique shape and flexibility.
- Due to the absence of a cell wall, mycoplasma cells can adopt various shapes, including spherical, filamentous, or pleomorphic forms.
- The typical size of mycoplasma cells ranges from 0.1 to 0.5 micrometers, making them significantly smaller than most other bacteria.
- The small size of mycoplasma cells allows them to pass through filters that would typically retain bacteria.
- Mycoplasma cells have a plasma membrane that contains sterols, providing structural stability.
- They possess a single circular chromosome and lack membrane-bound organelles.

PPLO:
- As mentioned earlier, PPLO is an older term used to describe a group of tiny bacteria-like organisms that were initially associated with pleuropneumonia in animals.
- However, it was later discovered that these organisms are closely related to mycoplasma and share similar characteristics.
- PPLO cells are also extremely small, ranging in size from 0.1 to 0.5 micrometers.
- Like mycoplasma, PPLO cells lack a cell wall and have a flexible shape.
- They possess a plasma membrane with sterols, similar to mycoplasma cells.
- PPLO cells have a single circular chromosome and lack membrane-bound organelles.

Conclusion:
In conclusion, both mycoplasma and PPLO refer to the same group of bacteria-like organisms that lack a cell wall. These organisms are considered the smallest known free-living cells capable of self-replication. The typical size of mycoplasma/PPLO cells ranges from 0.1 to 0.5 micrometers, making them significantly smaller than most other bacteria. However, it is important to note that there may be variations in size within this range among different species of mycoplasma/PPLO.

Mycoplasma is also called pplo means pleuro pneumonia like organisms..Hence both are same and smallest living cells.