Apoptosis: Definition, Importance, Role & Pathway

Apoptosis is a type of cell death in which a predetermined number of cells die without releasing hazardous compounds into the environment. It's also known as cellular suicide or planned cell death. The most well-understood type of programmed cell death is this. It necessitates the death of a cell yet benefits the entire organism. 

This is a systematic procedure in which the contents of the cell are packaged into little membrane packets for collection by immune cells. By removing cells throughout development and eliminating possibly malignant and virus-infected cells, it aids in the maintenance of body equilibrium.

Keyterms: Apoptosis, Cell, organism, environment, cell death, equilibrium, cell membrane, cancer cells

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Apoptosis: Definition

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Apoptosis is defined as “A normal biological process in which cells self-destruct in order to keep the body running smoothly.”

Apoptosis ​

In other words, apoptosis is a type of cell death in which a cell dies as a result of a succession of molecular events. This is one of the mechanisms by which the body eliminates undesired or abnormal cells. In cancer cells, the apoptotic process may be inhibited. Also referred to as "planned cell death".

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Apoptosis: Process

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Apoptosis is a biological process that happens in all multicellular organisms, including plants and animals. It eliminates cells from organisms that should no longer be a part of them. This process is critical for human development as well as the formation and maintenance of a healthy immune system. The word apoptosis comes from the Greek word apoktosis, which means "falling off." Kerr, Wyllie, and Currie were the first to introduce it. Apoptosis kills between 50 and 80 billion cells every day in an adult individual. Infected cells, pre-cancerous cells, and other cancer cells are successfully destroyed during this biological process, which maintains the equilibrium of cells in the human body. As a result, it is a critical process that is responsible for the normal development of cells, cell cycle maturation, and the maintenance of cell functions and activities. 

Apoptosis Process

Apoptosis occurs in all vertebrates with digits, such as fingers and toes. Fused toes or fingers are the result of a minor apoptotic error. Another example of apoptosis is the loss of a tadpole's tail as it develops into a frog.

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Classification of Apoptosis Pathways

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Apoptosis pathways can be divided into two categories.

1. The mitochondrial pathway is also known as the intrinsic pathway. Due to the identification of DNA damage, the cell receives a signal to destroy itself from one of its own genes or proteins.

Classification of Apoptosis Pathways

2. The death receptor pathway is also known as the extrinsic pathway. A cell receives a signal from other cells in the organism to initiate apoptosis. When a cell has outlived its usefulness or is no longer a good investment for the organism to support, this is triggered.

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Steps in Apoptosis

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• Shrinkage of Cell- The reduction of cell volume is a universal hallmark of programmed cell death, as shown in all occurrences of apoptosis.
• Cell Fragmentation- The DNA in the cell's nucleus condenses and breaks into uniformly sized fragments in this step.
• Collapse of Cytoskeleton- The cytoskeleton of the immature organism collapses at this stage.
• Disassembly of the Nuclear Envelope- At this point, the nuclear envelope is disassembled.
• Release of Apoptotic Bodies by Cells-  At this stage, cells go through morphological changes such as membrane blebbing, the development of thin membrane protrusions, and the generation of discrete apoptotic bodies.

Steps in Apoptosis

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Importance of Apoptosis

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• Apoptosis contributes to the sculpting of numerous organs and tissues throughout the development of overproduced cells that eventually die of natural causes.
• Every second, almost one lakh cells in the human body die by apoptosis, while a similar amount are generated by mitosis.
• In a day, roughly 29 to 30 billion cells die in youngsters aged 8 to 14.
• Apoptosis causes the epithelial lining of our bodies to alter every 23 days.

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Apoptosis and Its Function

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1. Cardiac remodelling, also known as systolic and diastolic dysfunction, is a process in which heart chamber dilatation and wall weakening occur in conjunction with systolic and diastolic malfunction.
2. Pancreatic cancer pathology - pancreatic cancers resist apoptosis, which could lead to new molecular treatments for pancreatic cancer.

Apoptosis and Its Function

3. Thisapoptosis behaves like a stone sculptor, removing the substance and revealing a new shape.
4. Apoptosis is a quick and irreversible process that develops in cancer cells to rapidly destroy defective cells.
5. Bone-Related Diseases Pathogenesis and Treatment - Apoptosis dysfunction may play a role in malignant transformation as a cell dysregulation. The death mechanism plays a role in the progression of osteoporosis.

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Examples of Apoptosis

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1. Mouse Feet - During embryonic development, mice's feet begin as flat, spade-shaped objects. The process of apoptosis causes the feet to divide into five different toes as they develop. The cells are joined in order to generate different gaps between them.

Examples of Apoptosis

2. Developmental Stages of Tadpole to Frog - The best and most spectacular example of apoptosis is found in frog tadpoles, which destroy and reabsorb all of their body structures as they develop into frogs. As the tadpole matures, apoptotic signals cause cells in the gills, fins, and tail to die. The raw material of the dead cells becomes a key material for new growing limbs and also serves as a supplement as needed.

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Apoptosis and Cancer: Is there a Link?

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Cancer is defined as the uncontrolled division of cells that results in the formation of a tumour. These undesirable cells can be removed from the body if apoptotic signalling works properly. The ability of cancer cells to avoid apoptosis and hence grow uncontrollably is the primary cause of cancer.

Apoptosis and Cancer

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Things to Remember

• Apoptosis is a type of cell death in which a predetermined number of cells die without releasing hazardous compounds into the environment.
•  It's also known as cellular suicide or planned cell death.
• Apoptosis is a biological process that happens in all multicellular organisms. It eliminates cells from organisms that should no longer be a part of them.
• Apoptosis is divided into two pathways: The mitochondrial pathway is also known as the intrinsic pathway while the death receptor pathway is known as the extrinsic pathway.
• Apoptosis contributes to the sculpting of numerous organs and tissues throughout the development of overproduced cells that eventually die of natural causes.
• The best and most spectacular example of apoptosis is found in frog tadpoles, which destroy and reabsorb all of their body structures as they develop into frogs.