According to DigoPaul, the concept of cell (a word from the Latin cellŭla) has three main uses. On the one hand, it refers to the primordial constituent of living beings, which has the ability to reproduce independently and is composed of a cytoplasm and a nucleus that are protected by a membrane.
The aforementioned cytoplasm is characterized because it is found between the other two mentioned parts, the nucleus and the membrane, because it is formed by the so-called cellular organelles (mitochondria, chloroplasts, ribosomes, endoplasmic reticulum, lysosomes…) and because it has three fundamental functions.
Specifically, these three aforementioned functions are: structural because not only is it the one that shapes the cell but also the key to its movements; the nutritive because it has substances that are later transformed into energy; and the storage one, since it keeps reserve substances.
For its part, the second component of the cell is the nucleus. This determines that there are two clearly delimited types of those. Thus, on the one hand, there are the so-called eukaryotic cells, which are those with a true nucleus separated from the cytoplasm; and on the other, there are the prokaryotes in which the different elements of that one are not only not defined but also appear mixed with said cytoplasm.
And finally, as we have mentioned previously, there is the membrane that is characterized by being semi-permeable, dynamic and with the capacity to modify itself. Likewise, it is necessary to underline the fact that it is made up of two organic substances such as lipids and proteins.
Among the most relevant functions of this third component are to isolate and protect that of what is outside, to regulate the passage of nutrient substances to the cell and the output of waste, and finally, in relation to the previous purpose, allowing or denying the passage of substances.
On the other hand, a cell is a group of individuals that functions independently within an organization, be it political, terrorist, religious or otherwise. To cite an example that allows us to appreciate this meaning: “Those responsible for the attack were three men belonging to an Al Qaeda cell that operates in Europe. “
Finally, the notion of cell also makes it possible to mention a cell or cavity of small proportions (such as, to mention a specific case, the cell of a monastery).
In the case of the cells of living organisms, they usually have microscopic dimensions. According to the number of cells they have, living beings can be classified as unicellular (they have only one cell, for example: protozoa) or multicellular (they have many cells, like humans, we have hundreds of billions).
In 1839, Matthias Jakob Schleiden and Theodor Schwann proposed the cell theory, which states that all organisms are made up of cells and that these are derived from other precedents. In this way, vital functions emanate from the interaction between cells, which even transmit genetic information from generation to generation.
It can also differentiate between two large types of cells: prokaryotes (which do not have a differentiated cell nucleus, but rather their DNA is dispersed in the cytoplasm) and eukaryotes (they present genetic information in a cell nucleus).