Apoptosis - Definition, Process and Its Significance

Do you know how many cells are present in our body? More than billions. These cells are programmed to die in an orderly process, which is known as Apoptosis. This cell death occurs in multicellular organisms to maintain the balance in the development of the body.

Table of Contents:

What is Apoptosis?
Apoptosis Pathways
Process of Apoptosis
Significance of Apoptosis
Role Of Apoptosis
Relationship Between Apoptosis and Cancer
Practice Problems
Frequently Asked Questions

What is Apoptosis?

Apoptosis is a natural process of a programmed sequence of cell death that occurs in all multicellular organisms, including plants and animals. This process removes the cells from the organisms that expire in the organism. It is also known as cellular suicide. Apoptosis plays an important role in the healthy development of the immune system of the body by eliminating potentially cancerous and virus-infected cells.

Apoptosis Pathways

The Apoptosis process is classified into two pathways:

Extrinsic Pathway

It is also called the death receptor pathway. In this process, a cell receives a signal to initiate apoptosis from other cells of the body. This pathway triggers apoptosis in response to external stimuli to bind at death receptors on the cell surface. Then the receptor initiates caspase activation. Thus the cell is no longer needed for the organism.

Intrinsic Pathway

It is also called the mitochondrial pathway. The cell receives signals from one of its own genes to destroy itself. This internal stimulus is because of biochemical stress or any detection of DNA damage.

Process of Apoptosis

Cell Volume Shrinks: In apoptosis, the cell volume is decreased, which is one of the common characteristics of programmed cell death.

Cell Fragments: The DNA in the nucleus of the cell breaks into equal fragments and is released in the surrounding environment.

Cytoskeleton Collapses: When the organism is fully developed, the cytoskeleton of immature cells collapses.

Nuclear Envelope Disassembles: At this step, the nuclear envelope is disassembled and removed from the reactor.

Cells Release Apoptotic Bodies: Finally, Some morphological changes occur in the cells, like membrane blebbing, thin membrane protrusion formation and generation of distinct apoptotic bodies.

BMG Labtech

Source: BMG Labtech

Significance of Apoptosis

Here is why Apoptosis is significant:

Apoptosis maintains homeostasis in the organisms.
It maintains the constant cell numbers in the organisms.
It eliminates unwanted cells and dangerous T-lymphocytes from the body.
It contributes to the sculpturing of many organs and tissues by programmed cell death.
It is responsible for cell development.

Role Of Apoptosis

Apoptosis plays an important role in our body of which some are listed below:

Apoptosis is responsible for the separation of the fingers during the development of the foetus.
The neural tube is closed in the dorsal part as the result of Apoptosis.
While determining the sex of the foetus, the Wolffian ducts are removed by programmed cell death.
Responsible for the size of the body and organs.
Apoptosis rapidly functions by eliminating dysfunctional cells.

Relationship Between Apoptosis and Cancer

Cancer is the result of uncontrolled growth or division of cells within the body, which develops as a tumour. The normal cell is transformed into malignant cells. Apoptosis works to remove these unwanted cells to reduce the risk of cancer and prevent cells from multiplying uncontrollably. Thus the Apoptosis process should take place to prevent cancer.

Practice Problems

Q1. In which of the following do the cells receive signals from their DNA to destroy?

A. Mitochondrial pathway
B. Extrinsic pathway
C. Internal pathway
D. Death receptor pathway

Ans : A. Mitochondrial pathway

Intrinsic, also called the mitochondrial pathway, is when a cell receives signals from one of its own genes to destroy itself.

Q2. Which of the following is eliminated by Apoptosis?

A. Red blood cells
B. B-lymphocytes
C. T-lymphocytes
D. Platelets

Ans: C. T-lymphocytes

Apoptosis eliminates the unwanted cells and dangerous T-lymphocytes from the body.

Q3. Dysfunction of the Apoptosis can lead to?

A. Thyroid
B. Cancer
C. Viral fever
D. Bleeding

Ans: B. Cancer

Apoptosis works to remove these unwanted cells to reduce the risk of cancer and prevent cells from multiplying uncontrollably.

Frequently Asked Questions

Q1. What is an example of Apoptosis?
Answer: When a tadpole transforms into a frog, the entire structure, like its gills, fins and tail, are destroyed as the result of Apoptosis.

Q2. What causes Apoptosis?
Answer: Caspase is a proteolytic enzyme that causes cell death or apoptosis by removing specific unwanted proteins in the cytoplasm and nucleus.

Q3. What diseases cause dysfunctional Apoptosis?
Answer: Dysfunction of Apoptosis is associated with autoimmune diseases, bacterial and viral diseases, heart diseases, and cancer.