The cell is known as the anatomical, physiological and original unit of all living beings. Each one is a constituted and organized portion of matter capable of developing all the activities associated with life: nutrition, relationship and reproduction, in such a way that it can be considered a being with a life of its own. Inside, many chemical reactions take place that allow them to grow, produce energy and eliminate waste. You get energy from your food and eliminate substances you do not need. It responds to changes that occur in the environment and can reproduce by dividing and forming others of itself.
Cell classification
Table of Contents
All living organisms are made up of these anatomical units, and depending on whether they have one or more, they can be classified as unicellular (bacteria, euglena, amoeba, etc.) and multicellular (man, animals, trees, etc.).
The size can be very varied, generally they are very small, for their observation a microscope must be used. The diameter of can be between 5 and 60 microns. In addition, due to differences in size, they present a wide variety of shapes (spherical, conical, flattened, irregular, polyhedral, cane, among others).
Most consist of three basic structures: the plasma membrane; which is the main barrier that establishes what can enter or exit it. The cytoplasm, which occupies most of the interior and within it there are other structures (organelles), which are responsible for carrying out the activities for its operation (mitochondria, ribosome, lysosome, vacuole, among others). And finally; the nucleus, which functions as a control tower that directs and orders everything that happens within the anatomical unit; it contains all the genetic material (DNA and RNA).
On the other hand, in the political sphere this word presents another definition, since it is seen as a group of affiliates that constitute an organization or unit linked to a common center, but independent from each other.
According to the internal structure, these can be: prokaryotes and eukaryotes. The former present a dispersed genetic material within the cytoplasm since they do not present a defined nucleus, for example, bacteria and algae. The latter if they have a well-defined nucleus, they are represented by protozoa, the plant and the animal.
Prokaryotic cell
They are organisms with very simple structures, without nuclei, most of them are unicellular, but it may be the case of some multicellular. Bacteria and cyanophytes or blue-green algae are characterized by the fact that their DNA is not isolated by a nuclear envelope.
The structure is very simple and they do not have a system of compartments limited by membranes. They are made up of six elements, these may or may not be present in its structure:
- Cellular wall
- Plasma membrane
- Cytoplasm
- Compartments
- Nucleoid
- Organelles
Prokaryotes are small, unicellular organisms limited by a plasma membrane. On the membrane, it has a second cell wall, and in some cases even a third, which is called a capsule.
The wall is a rigid structure that shapes the anatomical unit and has a different constitution than Gram positive and Gram negative bacteria.
Beyond the wall, many bacteria have a layer of polysaccharides or polypeptides, called a multi-function capsule.
Eukaryotic cells
They are much more evolutionary, large and modern than prokaryotes, they are characterized by having membranous organelles such as mitochondria, endoplasmic reticulum and Golgi apparatus.
It represents the evolution of life and established the foundations for greater biological diversity, as well as the possibilities of the specific anatomical units of multicellular organisms, originating higher kingdoms such as plants, fungi, animals and protists.
There are three types:
Animal cell
They do not have plastids or cell walls, they are formed by very abundant small vacuoles
Plant cell
It is covered by a cellulose wall and proteins that protect its membrane and make it stronger, more resistant and with chloroplasts conducting the chlorophyll necessary for photosynthesis.
Fungi Cells
Its wall is similar to the vegetal one, it contains chitin, for this reason it has less cellular definition. It is considered to be between the vegetable and the animal as it does not photosynthesize.
They have two fundamental functions that are:
- Self-reproduction.
- Self-preservation.
Multicellular Organisms
As their name indicates, they are organisms composed of more than one anatomical unit, these are independently integrated. Their development is linked to the specialty and division, these are efficient, but despite this, they depend on others to meet their needs and survive.
The amount of this type is variable, they can be from a few tens to millions of them, these multicellular organisms are found in the:
- Animals.
- Plants.
- mushrooms.
- Ciliates.
- Algae.
- Foraminifera.
Unicellular Organisms
They are organisms formed by a cell, that is, in them all life processes take place, for example, food, reproduction, digestion and of course excretion. Generally they cannot be seen, they are microscopic, for this reason they are called microorganisms.
The best known organisms of this type are:
- Amoebas.
- Plankton.
- The bacteria.
Cell Characteristics
They are minimal and fundamental units in organisms. These have functional and structural characteristics.
Structural Characteristics
- They are wrapped or surrounded by a membrane that separates and communicates with the outside, is responsible for controlling their movements as well as the electrical potential. This characteristic is different in each type of these; plant, animal, fungi and bacteria.
- Inside it has a membrane where it houses the cytosol and cellular elements.
- Inside they store genetic material in the form of DNA and ribonucleic acid, as well as proteins and enzymes that keep metabolism activated.
Functional Characteristics
- As they transform, they feed on substances, release energy and eliminate waste through metabolism.
- These feed, grow and divide, forming another unit exactly like the original, through the process called cell division.
- As part of a cycle, they undergo changes in their shape and functions, this process is called cell differentiation.
- These can communicate with others, through chemical signals, such as hormones or neurotransmitters. In addition, they respond to chemical and physical stimuli, both inside and outside.
- In their evolution, they undergo hereditary transformations, these influence their adaptation to a specific environment.
Cell biology
It is specifically the discipline specialized in the study of what the cell is. This scientific specialty focuses on the structure, the functioning, in what way it is composed, the interactions and properties of these microscopic organisms and, most importantly, they feed on information related to the genetics, immunology and biochemistry of living beings.
Some of the goals of cell biology are:
- Recognize the composition of the cytoplasm.
- Differentiate the elements of their function such as genes and genomes.
- Achieve, in a general way, a vision of these and their origin.
- Differentiate polar and nonpolar covalent bonds.
Auxiliary disciplines of cell biology
As this is a very specific science, its study can be applied to other disciplines, some of them are:
Cytology
It is in charge of the study of the animal anatomical unit.
Anatomy
It studies them but from the microstructural point of view, that is, it describes the organs, tissues, etc.
Biochemistry
It is responsible for studying living beings and their molecular structure and the changes suffered in their matter and at the anatomical level.
Genetics
Study the genetic content found within the cell and heredity.
Cell Parts
This is the smallest, but at the same time, the most functional part of the body. This performs the functions of self - preservation, self-reproduction and some of its parts are:
Plasmatic Membrane
It is a layer in charge of controlling the entry of nutrients to its interior, as well as the elimination of waste. This membrane protects the cytoplasm and surrounds it in its entirety, it is made up of a mixture of proteins and lipids, as well as protecting the nucleus or nuclei as the case may be.
Cytoplasm
Here are located the ribosomes, the Golgi apparatus, mitochondria and other organs. The cytoplasm is formed by the mixture of organic and inorganic substances plus water, which gives it a viscous consistency. It is located between the plasma membrane and the nucleus of the cell. It intervenes in their movement and keeps the cellular organs floating.
Cell nucleus
It is the area where the DNA or chromosomal substances or chromatin are found. The nucleus is located in the center of the cytoplasm, it is spherical in shape and covered with a double membrane. Inside it is the nucleolus, formed by proteins and ribonucleic acid, this is responsible for the creation of ribosomes.
It is important to highlight that the cell theory is used in biology as a resource to explain the constitution of living organisms, starting from anatomical units.
The principles of cell theory are:
- Living beings as a whole are made up of secretion products or cells.
- The structural unit of living matter is the cell and this can be enough to form an organism.
- All these arise from the pre-existing ones and the division of these.
- It is the origin of all living beings.
- The main functions of an organism occur in and around them, in addition to controlling the substances they secrete.
- The physiological unit of life are cells.
- In them you will find all the hereditary information, in addition to being a genetic unit.
What are Stem Cells
They are responsible for supplying new cells to the body, they divide and can form many of themselves and others of different types, for example, when new anatomical skin units are formed, some are mothers of this type and others fulfill the production function of melanin pigments.
When the human being suffers damage to these, by some accident, injury or loss of health, at that moment the stem cells are activated, regenerating the damaged tissues and replacing those that die. In this way they prevent premature aging and keep human beings healthy.
To understand the process of cell specialization, it must be known that each antomic unit of the body contains all the genetic material (DNA) necessary in its nucleus, to become another of any type.
Specialization takes place in embryonic development. Once the ovum is fertilized, the zygote begins to divide rapidly, giving rise to new anatomical units. As the body of the embryo develops, they decide what type they will become, that is, cell specialization is taking place, which is an irreversible process.
These are classified according to their potential for differentiation into:
- Totipotent.
- Pluripotent.
- Multipotent.
- Unipotent.
There are some types of diseases, including cancer, that prevent stem cells from developing in a normal way. If these are not normal, they are not capable of producing anatomical blood units. When a stem cell transplant is done, new ones are given.
The main stem cell transplants are:
- Autologous transplantation: it is also called autotransplantation or chemotherapy, it is a high autologous dose of mother anatomical units.
- Allogeneic transplantation: also called an Allogeneic transplant, the patient receives the mother anatomical units of another person. For this procedure it is important to find a person who has a bone marrow compatible with the patient.
