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• Cell Death Reasons in multi-cellular organisms are apoptosis and necrosis.
One is natural cell death process that is apoptosis and other is because of
accidental harms, named as necrosis.
• Apoptosis is a natural process that is called as programmed cell death. It
is normal part of multi-cellular organisms and occurs because of the
biochemical changes. Apoptosis helps to eliminate unnecessary cells from
Figure 18.1:Apoptosis Phenomenon
• Apoptotic Bodies are smaller sized sealed membrane vesicles produces
when cells undergo programmed cell death. It can be seen easily in figure
18.1. Apoptotic antibodies help to prevent the inflammations by saving the
discharge of toxic cellular contents of dyeing cells during apoptosis.
• Cell Necrosis is the death of cells by accidents and unexpected accidents.
Necrosis can be result of radiation exposure, heat, trauma or decrease of
oxygen in arteries because of blood flow obstruction.
Figure 18.2: A close look of apoptosis and necrosis
• Intracellular proteolysis is breakdown of protein molecules into smaller
amino acids. Process is being done by breaking the peptide bonds between
protins and it take longer times. Proteolysis activity is enhanced by the
enzyme protease that helps to fasten the process of peptide bonds
• Intrinsic Pathway of Apoptosis is a process where Bcl-2 family controls
mitochondrial external layer permeabilization (MOMP). Pro apoptotic Bcl-2
proteins structure mitochondrial apoptosis-impelled channels (MAC) in the
external mitochondrial layer. These mitochondrial layer pores cause MOMP,
discharging cytochrome c and other cytotoxic proteins into the cytosol.
Figure 18.3A: Intrinsic Pathway of Apoptosis
A diversity of stress stimuli including development factor removal, heat
shock, and DNA damage trigger apoptosis intrinsic or mitochondrial
pathway. Mitochondria are concerned in both caspase-dependent and
caspase-independent apoptosis pathways. Oxidative damage through the
generation of endogenous reactive oxygen species (ROS) by mitochondria