Programmed Cell death || Apoptosis || Necrosis || Phagocytosis || Necrosis || Ligands || Receptors|| Genetics || Cell biology || Molecular Biology || Cell types || Cellular types || cell shrinkage || Initiation Caspases || Microbiology || Genetics ||Cell types || Necrosis vs apoptosis

1. APOPTOSIS
By
Kothagattu
Vandana

2. INTRODUCTION:
• Cell death by injury -mechanical damage -exposure to toxic chemicals
• Cell death by suicide -internal signals -external signals
• Apoptosis or programmed cell death, is carefully coordinated collapse of cell, protein
degradation, DNA fragmentation followed by rapid engulfment of corpses by neighboring
cells.
• Essential part of life for every multicellular organism from worms to humans.
• Apoptosis plays a major role from embryonic development to senescence.

3. WHAT MAKES A CELL DECIDE TO COMMIT
SUICIDE?
• Withdrawal of positive signals examples:
1. Growth factors for neurons
2. Interleukin-2 (IL-2)
• Receipt of negative signals examples:
1. Increased levels of oxidants within the cell
2. Damage to DNA by oxidants
3. Death activators:
a. Tumor necrosis factor alpha (TNF- )
b. Lymphotoxin (tnf-β)
c. Fas ligand (fasl)

4. NECROSIS VS. APOPTOSIS

6. STAGES OF APOPTOSIS

7. MORPHOLOGICAL EVENTS:
1. Cell shrinkage
2. Organelle reduction
3. Mitochondrial leakage
4. Chromatin condensation
5. Nuclear fragmentation
6. Membrane blebbing & changes

8. APOPTOSIS: PATHWAYS

9. REGULATION OF APOPTOSIS:
• Stimuli → apoptosis → selection of targets
• Apoptosis by conflicting signals that scramble the normal status of cell
• Apoptotic stimuli → cytokines, death factors (fasl)
• DNA breaks → p53 is activated → arrest cell cycle or activate self-
destruction.

10. IMPORTANCE OF APOPTOSIS:
• Important in normal physiology / development
A. Development: immune systems maturation, morphogenesis, neural
development
B. Adult: immune privilege, DNA damage and wound repair.
• Excess apoptosis
A. Neurodegenerative diseases
• deficient apoptosis
A. Cancer
B. Autoimmunity

11. CONCLUSION:
• An important process of cell death
• Can be initiated extrinsically through death ligands (e.G., TRAIL, fasl) activating initiator
caspase 8 through induced proximity.
• Can be initiated intrinsically through dna damage (via cytochrome c) activating initiator
caspase 9 through oligomerization.
• Initiator caspases 8 and 9 cleave and activate effector caspase 3, which leads to cell death.

12. THANK YOU