Prokaryotic cells, also known as protocells or prokaryotic cells, are cells that do not have a defined cell nucleus and, therefore, the cellular genetic material is dispersed in the cytoplasm.
In addition to prokaryotic cells, there are also eukaryotic cells and they are distinguished by their functioning and the complexity of their cellular structure.
Prokaryotic cell structure
Structure of a prokaryotic cell
- Capsule: coats the cell externally;
- Cytoplasm: gelatinous substance responsible for maintaining the shape of the cell;
- DNA: carries the cell’s genetic information;
- Flagellum: enables cell locomotion;
- Plasma membrane: controls the exchange of substances between the cell and the external environment;
- Cell wall: gives shape to the cell;
- Pilus: allows the bacteria to be fixed in the medium;
- Ribosome: structure responsible for the production of proteins.
Main features of prokaryotic cell
We say that the prokaryotic cell does not have a true nucleus, as this is formed by some membranes that constitute the “nucleoid”, that is, a non-separated nucleus. Its most peculiar characteristic is the lack of nuclear envelope to subdivide the cell nucleus.
Prokaryotes have DNA , which can be seen as a ring without proteins (they are devoid of proteins).
This genetic material is formed only by a circular DNA strand. Since its nucleus is separated from the rest of the organism by a thin protective layer, that filament is completely mixed with the cellular hyaloplasm.
Thus, as its nucleus (nuclear envelope) lacks a nuclear membrane, all DNA is dispersed in the cytoplasm in the form of ribosomes, which carry out protein synthesis. Remember that only the ribosome can be found in the cytoplasm.
The plasma membrane has permeability, antigenic molecules. It is capable of exchanging substances with the outside environment, as well as performing the function of a protective cell wall.
These cells are nourished through sources of carbon and energy obtained by the actions:
- phototrophic action (use sunlight as an energy source)
- chemotrophic action (harness energy from chemical compounds)
Also know the characteristics of the eukaryotic cell .
prokaryotic beings
Prokaryotes are organisms of relatively small size and with a very simplified composition and functioning, which makes these beings the first living organisms on the Planet.
They arose billions of years ago as a group of single-celled creatures. They were able to survive in all environments, including inhospitable ones, where temperature and pH conditions would be considered unsuitable for the development of other living beings.
Prokaryotic cells can be bacteria or Archaea. These protobacteria or protocells (Bacteria, Cyanophytes and Mycoplasmas) can take the form:
- spirilla (elongated and helical beings);
- cocci, cocci and cocci (relatively spherical organisms);
- bacilli, bacillus and bacilli (slightly elongated);
- vibrios (bent into an arc or comma shape).
Furthermore, prokaryotic cells do not form multicellular organisms and can live in isolation or form anaerobic or aerobic colonies. Despite the great difference, these cells preserve an anatomical unit among themselves.
Gain more knowledge by reading about the Monera Kingdom .
reproduction of prokaryotic cells
Prokaryotic cells do not reproduce by mitosis. Asexual binary fission recombines genetic material by transduction or transformation. It even allows a species to create antibiotic resistance from that obtained by another organism of a different species.
In this reproduction, chromosome condensation does not occur due to the absence of mitotic processes. Thus, through fission, septa are formed and travel from the surface to the cell nucleus, where the cell is divided in two.
To learn more, read the articles on
- Cytology
- Cell
- cell types
- asexual reproduction
Difference between prokaryotic and eukaryotic cells
The basic division between cells is the classification into prokaryotes and eukaryotes. These two cell types differ mainly by cell structure.
While the prokaryotic cell is characterized by the absence of a nucleus and simple structure, the eukaryotic cell has a defined nucleus and a more complex structure.
Although they exhibit the same molecular structure as eukaryotes, prokaryotes lack some organelles, such as:
