Body of all living organisms constitute of innumerable cells with specific functions. The cell theory says that the main or primary unit of life is cell and the entire living organism at least has one cell. Off course the number of cells in an organism differs but majorly the living cells are categorized into 2 main groups: Prokaryotic cells and Eukaryotic cells. Eukaryotic cells are known to have evolved from the prokaryotic cells and are the most advanced. Almost all living organisms like animals, plants, protozoan, fungi and algae are made up of eukaryotic cells. But prokaryotic cell types are only found in bacteria.
Prokaryotic cells are comparatively very small than the eukaryotic cells and lack the membrane bounded by nucleus. The internal structure of this cell is very limited and can be observed under the microscope. These are mostly found in organisms belonging to monera kingdom (bacteria) or the cyanobacteria (blue green algae). They do not posses any chromosomal DNA and their genetic constituents are in the form of round loop termed as plasmid. The bacterial cells are very small in size and are around 1-2µm in diameter and 10 µm long. They can be found in three shapes: Spherical, spiral or rod-shaped. Their method of reproduction or cell division is simple binary fission as they are haploid in nature.
The prokaryotic cells posses a nucleus but there is no presence of nuclear membrane. More often than not one circular chromosome which is composed of DNA is present which is connected with proteins (usually histone). The cells do not have any nucleolus and the whole nuclear body is known as nucleiod.
The cytoplasmic membrane of prokaryotic cells is made up of phospholipid bilayer fluid which is mostly devoid of sterols. Many times hopanoids- a sterol resembling molecules is traced in bacteria. During the protein synthesis the ribosomes which are composed of 50S and 30S subunit come together and produce 70S ribosome. You do not find any internal membrane bounded organelles like the endoplasmic reticulum, Golgi apparatus, mitochondria or lysosomes in prokaryotic cells. No presence of chloroplasts and hence photosynthesis is carried out in the infoldings or in the cytoplasmic membrane extensions. The actin like protein present in the cell helps to form the cell shape along with the cell wall.
These cells are very simple in structure and are very small and since smaller size has greater surface to volume ratio, anything (nutrients) can be easily and more speedily absorbed and reached to every part of the You do not have access to view this node. But in case of eukaryotic cells the surface to volume ratio is less due to their large size and hence it needs other organelles to perform various cell functions.
A bacterium is the most prominent organism in this category. It performs many important functions such as fermentation, decomposition, improving digestion etc. Its participation in nitrogen cycle helps in restoration of nitrogen to the soil in the form of nitrate which is an essential nutrient for the soil. It also takes in the excess of sulfur instead of oxygen during its metabolism.