Question

Discuss apoptosis and necrosis. Compare and contrast the two.

Answer 1

Apoptosis

Apoptosis is programmed cell death Chracterized by cell shrinkage, chromatin condensation, formation of cytoplasmic blebs and apoptotic bodies, phagocytosis by macrophages or adjacent cells.

Necrosis

Necrosis is spectrum of morphologic changes that follows cell death in living tissues.

Apoptosis	Necrosis
Programmed cell death	premature cell death
Naturally occurring physiological process	pathological process caused by external agents like trauma,toxins etc
Occurs by shrinkage of cytoplasm followed by condensation of nucleus	occurs by swelling of cytoplasm and mitochondria followed by cell lysis
Chromatin is aggregated in apoptosis	No any structural changes occurs
Is a localised process, destroy individual cells	Destroy a group of cells
It is a caspase dependent pathway	It is a caspase independent pathway
Phagocytized either by phagocytes or adjacent cells	phagocytized by phagocytes
It is beneficial , although its abnormal activity cause disease	Always harmful to organism
Involved in controlling the cell number in the body	Involved in the induction of immune system and defending the body from pathogen
Prelytic DNA fragmentation occurs	postlytic DNA digestion occurs

Hence apoptosis is an active programmed cell death ,naturally occurring physiological process while necrosis is an passive accidental cell death caused by external agents like trauma , toxins etc.