The bacterium is a unicellular and prokaryotic microorganism, which means it has no nucleus. Bacteria, along with protozoa, fungi and algae, belong to the category of microorganisms, which are microscopic life forms.
The bacterium is indispensable for life on Earth and exists in the most diverse environments. It is the organism that is found in greater abundance on our planet.
There are bacteria that coexist within other organisms in symbiotic relationships called endosymbionts. The most common example is the bacterial flora of our digestive tract that helps us process nutrients that we are not able to digest without your help.
According to their form, bacteria are generally classified as: bacilli (cane), spirils (spirals) or coconuts (spherical).
There are also harmful bacteria for our body. The pathogenic bacteria are those that cause disease in our body such as, for example, germs, typhoid, ulcers, salmonella, cholera and tuberculosis.
The father of microorganisms is considered to be the Dutch merchant Anthony van Leeuwenhoek (1632-1723), who first observed with his microscope the first bacteria or prokaryotic cells.
Bacteria have the following characteristics:
- They are prokaryotes: they have no nucleus and are formed by a single chromosome.
- They have a unique and circular DNA: they swim free in the cytoplasm.
- They reproduce by binary fissions or cell division: the DNA is divided and then its cytoplasm is also divided to create two daughter cells.
- It has a cell wall composed of peptidoglycan: very resistant because it is straight and unbranched.
- They have different methods of metabolisms and habitats.
- Some have cilia or flagella.