In cell biology, one of the most important processes is that of apoptosis, which refers to programmed cell destruction. In this process, the organism, upon detecting a damaged cell, sends a signal so that the cell can carry out its own destruction, in order to prevent the spread of degenerative diseases.
If you want to know what it is, its phases, how it occurs, causes and more, here we show you.
What is the meaning of apoptosis in biology?
In biology, the molecular process in which the cell leads to its own death. This type of cell death is a path programmed or caused by the organism itself in order to control the excessive growth of cells, that is, it is a genetic control to prevent growth of cells.
How this process occurs allows damaged cells to be destroyed, or the cells that have finished their useful life cycle, thus avoiding pathologies such as cancer or degenerative diseases. For this reason, it has been a source of research and attention within cell biology, since it seeks to find a cure for such pathologies.
The first person to discover cell death was Rudolf Virchow in the XIX century. This German pathologist investigated why this destruction happened based only on macroscopic parameters, in other words, what could be seen with the naked eye. In this way, he succeeded in defining degeneracy and necrosis suffered by the cells.
It was not until the 20th century that the term “apoptosis” was first used, by researchers Currie and Wylliemanaging, in this way, to define well what this molecular process was about.
When establishing what apoptosis is, it should be clear that not to be confused with necrosis. The first is a programmed and necessary death for the organism, while necrosis is a case of unwanted and unprogrammed cell death. This occurs due to the death of tissues, so endangers the health of the body being a chaotic and irreversible process. Also, this only arises in response to bacterial infections or interruption of blood flow to tissues.
What is cell apoptosis?
In medicine, cell apoptosis is defined as the process where the death of a cell occurs. This happens during the stages of development of an organism, in order to be able to discard cells that form unnecessarily. For example, in humans, those that arise between the fingers of one hand.
However, this is not a biological process that occurs only in the early stages. In adulthood, apoptosis allows get rid of all cells that are no longer useful or that have suffered some irreversible damage, this being an important quality to avoid degenerative diseases and cancer.
What is the process of apoptosis for?
This is a biological process that helps organisms to destroy and get rid of abnormal cellsthat are damaged or that are unnecessary so that they can later be replaced by cell regeneration.
They also play a important role in training of any organism, due to the fact that they can eliminate those additional embryonic tissues.
What are the causes of apoptosis?
Cellular apoptosis always occurs through physiological conditions, which force the cell to decide if it should survive or die. In this way, programmed cell death in any cell can be caused by various factors that affect it, such as:
- The disturbance of the cell cycle.
- A variation within metabolism.
- An anomaly.
- The lack of trophic factors in the cell.
What are the phases of apoptosis?
Apoptosis has Two phases: decision and execution. For these to be fulfilled, you must first go through an activation process, which can only occur for two things:
- By a positive Induction, which is when a ligand binds to one or more receptors.
- By a negative inductionwhich occurs thanks to the loss of suppressive activity, that is, the absence of growth factors or the reduction of the contacts present between the cells.
Once this cell destruction process is activated, we see that the decision phase begins. This occurs when the cell receives a death signal, so it must choose whether to trigger the processes that are linked to its destruction or whether to survive. During this moment, the mitochondria takes a fundamental place as an organelle.
In this way, the information will be sent to death receptors. These are characterized by having an extracellular domain, full of cysteine, and lies within the ‘death domain’, which is located in the cytoplasm. It is responsible for the activation of the apoptotic machinery. When it is already in its active state, information is sent to the interior of the cell through a complex system of interactions within the protein, which, in turn, activate various intracellular cascades.
Following this, second messengers allow dysfunction of organelles in the cytoplasm, such as the endoplasmic reticulum and mitochondria, to be achieved. Also, it stops regulation of enzyme complex activitywhich causes other protein functions to stop being regulated.
In this way, the production of free radicals can be activated and the activity of the cell’s internal transcription factors potentiated. This increase can cause severe cell damage, including cell death. In the same way, it usually alters the chain that transports the electrons, so that when the electrochemical potential of the membrane is lost, a metabolic change is noted through an oxidation-reduction reaction.
Once the cell receives the death signal, execution phase begins. In it, a series of biochemical processes are carried out inside the cell, which leads to the degradation of proteins.
In this we can see that calpains, caspases, group B granzyme and proteasomes are involved. By engaging this amount of proteases, the cell experiences intracellular and extracellular stimuli. In such a way that they manage to hydrolyze the specific sequences of tetrapeptides, which have an aspartate residue.
What is the importance of apoptosis in biology?
The importance of apoptosis lies mainly in the prevention of various diseases, by eliminating cells that have been previously irreversibly damaged. Because it is a cellular regulation, when this process is altered it is common for serious effects to be witnessed in the organism.
In the event that there is not enough cell death, that is, that apoptosis is being inhibited for some reason, the most common is that the organism develops tumors or other diseases.
Most cases of cancer, autoimmune diseases and viral infections are due to an excess of damaged cells in the organism. However, if there is an excess of apoptosis, the organism can also develop some diseases, syndromes and/or disorders. For example, AIDS, Alzheimer’s, epilepsy, Parkinson’s, rhinitis and amyotrophic lateral sclerosis and other diseases that affect the immune system are pathologies that arise due to excess of programmed cell death.
Examples of materials that undergo apoptosis
All organisms that are made up of cells suffer from apoptosis, due to the fact that it is a natural adjustment process. Even the cells of the nervous system (neurons) must also go through this process.
In this way, neurons that are no longer functional or that have suffered some damage can be supplanted by younger ones. However, this is a much slower destruction and regeneration than in the rest of the body.