What is the Difference Between Apoptosis and Programmed Cell Death

The key difference between apoptosis and programmed cell death is that apoptosis is a form of programmed cell death, while programmed cell death is the main process of inducing cell death through a sequence of steps, which include autophagy, apoptosis, and necroptosis.

Cell death is a common process in living organisms, including plants, that remove non-functional cells from the living systems. A programmed cell is the main process of inducing cell death through a series of systematic steps with false-proof mechanisms. Apoptosis and autophagy are subtypes of programmed cell death. Programmed cell death is an evolutionarily conserved process. This is an important aspect in multicellular organisms for morphogenesis during development and for the maintenance of tissue homeostasis in organs with ongoing cell proliferation.

CONTENTS

1. Overview and Key Difference
2. What is Apoptosis 
3. What is Programmed Cell Death
4. Similarities – Apoptosis and Programmed Cell Death
5. Apoptosis vs Programmed Cell Death in Tabular Form
6. Summary – Apoptosis vs Programmed Cell Death

What is Apoptosis?

Apoptosis is a form of programmed cell death that induces cell death in organisms when the cells become non-functional. It is led by various biochemical reactions, which lead to a number of morphological changes and eventually death. Such changes are shrinking of cells, nuclear fragmentation, blebbing, condensation of chromatin, mRNA decay, and DNA fragmentation. Apoptosis produces fragments called apoptotic bodies. These cells are engulfed by phagocytosis and are removed before the content leak outside and damage the surrounding.

Apoptosis is a highly regulated process, usually through intrinsic or extrinsic pathways. In the intrinsic pathway, the cells sense stress and kill themselves. In the extrinsic pathway, cells die due to signals from other cells. Both pathways induce cell death through the activation of caspases, which are enzymes degrading proteins or proteases. Excessive apoptosis causes atrophy while an insufficient amount of apoptosis causes uncontrolled cell proliferation, which causes cancer. Factors such as caspases and Fas receptors induce apoptosis, whereas the Bcl-2 family of proteins inhibits apoptosis. Apoptosis has positive effects on both the promotion and inhibition of apoptosis. Enhanced targeting of infected cells for apoptosis destroys infected cells. Inhibition of apoptosis also limits damages resulting from ischemia in neural and cardiac tissues. It also improves therapies for diseases such as HIV and diabetes mellitus.

What is Programmed Cell Death?

Programmed cell death or PCD is a death of a cell caused due to various events inside a cell that induces cell death. PCD is also referred to as cellular suicide. It is carried out by a series of biological processes in an organism’s lifecycle. Programmed cell death serves fundamental functions in the development of animal and plant tissues. Autophagy and apoptosis are forms of programmed cell death. Recent research data has found that necrosis occurs as a form of programmed cell death. Necrosis is the cell death that occurs due to external stimuli such as infection or trauma that take place in different formats. The type of necrosis that comes under programmed cell death is necroptosis. During this form of programmed cell death, it acts as a backup program to initiate cell death when the apoptosis signalling process gets inhibited by exogenous or endogenous factors. These factors include mutation or viruses.

Programmed cell death is a complicated and false-proof process. Therefore, programmed cell death only occurs when the cell is no longer functional and identified by different cellular mechanisms.

What are the Similarities Between Apoptosis and Programmed Cell Death?

• Apoptosis and programmed cell death are common processes in plants and animals.
• They induce cell death.
• Moreover, both processes are triggered when the cell becomes non-functional.
• Both apoptosis and programmed cell death function on similar parameters.

What is the Difference Between Apoptosis and Programmed Cell Death?

Apoptosis is a form of programmed cell death, while programmed cell death is the main process of inducing cell death through a sequence of steps, which includes autophagy, apoptosis, and necroptosis. Thus, this is the key difference between apoptosis and programmed cell death. Moreover, subtypes of apoptosis include intrinsic and extrinsic apoptosis, and subtypes of programmed cell death include apoptosis, autophagy, and necroptosis.

The below infographic presents the differences between apoptosis and programmed cell death in tabular form for side by side comparison.

Summary – Apoptosis vs Programmed Cell Death

Cell death is a common process in living organisms to remove non-functional cells from the living systems. The programmed cell is the main process of inducing cell death through a series of systematic steps with false-proof mechanisms. The key difference between apoptosis and programmed cell death apoptosis is a form of programmed cell death, while programmed cell death is the main process of inducing cell death through a sequence of steps, which includes autophagy, apoptosis, and necroptosis. Both apoptosis and programmed cell death are important aspects in multicellular organisms for morphogenesis during development and for the maintenance of tissue homeostasis in organs with ongoing cell proliferation.

Reference:

1. “Apoptosis.” Encyclopædia Britannica, Encyclopædia Britannica, Inc.
2. “Programmed Cell Death.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Apoptotic cell disassembly” By Aaron Smith, Michael AF Parkes, Georgia K Atkin-Smith, Rochelle Tixeira, Ivan KH Poon – Wikiversity:Draft:WikiJournal of Medicine/Cell disassembly during cell death (CC BY 4.0) via Commons Wikimedia
2. “Types of Cell Death” By Mertmetin96 – Own work (CC BY-SA 4.0) via Commons Wikimedia