In this article we will discuss the difference between apoptosis and necrosis. The natural process that leads to cell death is referred to as apoptosis, but when cell death occurs due to attack by certain external factors such as bacteria, viruses or fungi, or poisoning, injury, it is called necrosis.
Apoptosis is a self-controlled event that occurs under favorable physiological conditions and the cell itself actively participates in the process. During necrosis, cells cannot maintain homeostasis which leads to the flow of extracellular water and ions in the cells, even organelles such as mitochondria will swell and result in cell lysis.
Many occurrences of cell death have been observed in multicellular organisms. This naturally occurring phenomenon may be caused by internal or external factors. There are many morphological, physiological and biochemical differences in the two processes.
Now, in this article, we will discuss the key points where these two types of cell death processes vary. We will also consider the factors responsible for apoptosis and necrosis and how they are beneficial or harmful to an organism.
Definition of Apoptosis
Apoptosis is a cellular response commonly known as ‘programmed cell death’. It is triggered by many biological, chemical and physical factors. The entire process of cellular degradation is regulated by ‘caspases’ – a family of proteases (proteins) highly activated during apoptosis.
Apoptosis is an energy-dependent mechanism that is completed in several steps. When a cell is triggered to commit suicide, it immediately sends a signal to proteins known as ‘caspases’. Caspases act, the cell shrinks and develops blebs (bubble-like protrusions) on their surface. Cellular components begin to fragment and meanwhile caspases also trigger the production of DNases, enzymes that destroy DNA in the cell nucleus.
Within a few fractions of time, the cell breaks into small pieces, packaged in a membrane known as an apoptotic body. Subsequently, these fragments are cleared by macrophages. Immune cells are known to clear debris by the process of phagocytosis (eating cells).
Why is apoptosis carried out in the body? There are various reasons for apoptosis to occur, firstly if the cell is no longer needed by the organism which could be due to maintaining a balance of cell numbers, or perhaps because certain abnormalities are detected in the cells.
Apoptosis is a necessary process during infant development, when our toes and fingers join together to form a webbed structure in the womb. With the help of programmed cell death, the webbing will disappear and give ten separate fingers and toes. Even during the entire lifespan, apoptosis continues to work according to need and growth and to keep the body healthy.
Definition of Necrosis
The unnatural or unprogrammed death of cells is known as necrosis. The reason is that it is caused by infection, poisoning, injury, or attack by fungi, viruses, or bacteria. It is also said that necrosis can also occur due to hypoxia, which occurs due to improper oxygen supply to the surrounding tissues.
Necrosis begins when the cell is unable to maintain homeostasis, therefore extracellular ions and water can enter the cell, and cell organelles rupture and eventually cause cell rupture due to osmotic pressure.
Key Difference Between Apoptosis and Necrosis
Below are the key points highlighting the difference between the two types of cell death, namely apoptosis and necrosis:
- Apoptosis is programmed cell death that occurs naturally and at regular intervals in the body. Necrosis is premature cell death that is unnatural and can occur randomly in the body.
- Apoptosis is genetically controlled and is said to be natural death of the cell that is triggered by the cell itself, but necrosis is not genetically controlled, and cell death is pathological (not natural).
- Apoptosis is a naturally occurring cell death that does not require any treatment. on the other hand, necrosis requires treatment because it is not the natural death of a cell.
- Apoptosis is always beneficial to the body of an organism, whereas necrosis is harmful to the body of an organism because it can be fatal, sometimes causing cancer.
- Apoptosis is a self-derived process of cells, otherwise necrosis occurs due to external causes like bacteria, viruses, fungi or any poison.
- Cells shrink during apoptosis, whereas cells swell during necrosis.
- Nuclear fragmentation and chromatin condensation are signs of apoptosis, but in disorganized nuclear necrosis, and no chromatin condensation occurs, the organelles break apart instead of breaking into fragments.
- Since apoptosis is a natural process that occurs in the body, there are no physical symptoms. On the other hand, necrosis causes severe symptoms like inflammation and can also cause damage to the surrounding tissues and cells.
- Apoptosis is an energy-dependent process that requires ATP (energy), as it is an active process. Necrosis is an energy-independent process, and it is a passive process.
Similarity:
- Apoptosis and Necrosis cause cell death.
- This process occurs in both plants and animals, although the mechanism is different.
- Apoptosis and Necrosis do not occur in prokaryotes.
- In both processes, DNA is fragmented.
Red Thread | There are two types of cell death, Apoptosis and Necrosis, the first type is natural and self-initiated by the cells, while the second type is triggered due to certain external factors such as viral, bacterial or any kind of toxicity. So ultimately, this process brings about cell death but differs in the process of degradation and post-destruction effects of the cell.
