Cell it is the smallest basic structural and functional unit of the living being, being considered the smallest portion of a living matter.
It was discovered in 1665 by the English mathematician Robert Hooke, who observed cork cells through a microscope. It was he who gave the name "cell", from the Latin cella = small cavity, compartment or part of a house.
Cells are surrounded by a cell membrane and filled with a concentrated aqueous solution of chemicals called cytoplasm, where dispersed organelles are found.
There are 2 types of cells:
- Prokaryotic Cells: They do not have caryotheca (nuclear membrane). This group includes bacteria (archaebacteria and eubacteria);
- Eukaryotic Cells: Show the nucleus separated from the cytoplasm by the caryotheca. They make up the majority of living beings (protozoa, fungi, plants and animals).
Living beings can be classified as unicellular or multicellular, according to their cell number:
- single cell: Formed only by a single cell. They are bacteria, cyanophytes, protozoa, unicellular algae and yeasts;
- Multicellular: Formed by several cells. They are fungi, sponges, vegetables and animals.
In some multicellular beings the cells organize and form fabrics, which are sets of cells that act in coordination to perform a certain function. Tissues, in turn, group together and form the organs that make up the systems (digestive, nervous, respiratory, circulatory).