Cell biology is the specialization of biology that, using microscopes and other resources, is dedicated to the study of cells.
Cell is a word from the Latin cellŭla that 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 mainly composed of a cytoplasm and a nucleus that are protected by a membrane .
The cytoplasm is characterized because it is located between the other two parts mentioned (the nucleus and the membrane), being formed by the cell organelles or organelles (mitochondria, chloroplasts, ribosomes and lysosomes, among others). It should be noted that it has three fundamental functions: a structural one (not only does it give shape to the cell but is also key in its movements); a nutritive one (it has substances that are later transformed into energy) and a storage one (it keeps reserve substances).
cell nucleus and membrane
Another component of the cell is the nucleus . This determines that there are two clearly defined types of cells. Thus, on the one hand, there are eukaryotic or eukaryotic cells , which are those that have a true nucleus separated from the cytoplasm; and on the other hand there are prokaryotic or prokaryotic cells , in which the different elements of the nucleus are not only not defined, but are also present mixed with the cytoplasm.
And finally, as we have mentioned previously, there is the cell membrane that is characterized by being semipermeable, dynamic and with the capacity to modify itself. Likewise, we must emphasize the fact that it is made up of two organic substances. such as lipids and proteins .
Among the most relevant functions that this third component has are isolating and protecting the cell from what is outside; regulating the passage of nutrient substances into the cell and the exit of waste; and finally, in relation to the previous purpose, allowing or denying the passage of substances.
It should be noted that there are also other organelles in eukaryotic cells, such as the endoplasmic reticulum , the Golgi apparatus and the centrosome .
Endocytosis, phagocytosis and exocytosis are active transport mechanisms that cells develop to transport molecules.
Main features
The cells of living organisms usually have microscopic dimensions. According to the number of cells they have, living beings can be classified as unicellular (they have only one cell, as happens with protozoa) or multicellular or multicellular organisms (they have many cells, like human beings, who have hundreds of cells). billions forming tissues and organs).
In 1839 , Matthias Jakob Schleiden and Theodor Schwann proposed the cell theory , which states that all organisms are made up of cells and that they derive 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 be differentiated between two large types of cells, as we already indicated: 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). ).
There are also other possible classifications. It can be differentiated between an animal cell , a plant cell or a bacterial cell , for example.
A stem cell , meanwhile, is one from which other cells that have specialized functions can be born, such as somatic cells and germ cells . If we focus on the number of chromosomes, we can distinguish between haploid cells and diploid cells .
Regarding their location in the body, we can mention bone cells , muscle cells , adipose cells , pancreatic cells , liver cells , stomach cells and skin cells , among many others.
Erythrocytes (red cells), leukocytes (white cells), and platelets are blood cells.
The cell cycle
The cell cycle is the series of steps that allow a cell to grow and then divide. It is important to note that the cell can adopt a non-dividing state or a dividing state .
The non-division state is also known as interface . The synthesis of RNA (ribonucleic acid) and proteins occurs there; If the purpose of the cell is to continue cell division , in this instance it begins the duplication of its DNA (deoxyribonucleic acid).
The division state or M phase , for its part, involves cell division by mitosis . In the case of gamete production, meiosis of diploid cells takes place (which register two consecutive divisions to produce four haploid cells).
The term as a set of individuals or small cavity
On the other hand, a cell is a group of individuals that functions independently within an organization , whether of a political, terrorist, religious or other type. 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 allows mention of a cell or cavity of small proportions (such as, to mention a specific case, the cell of a monastery).