PowerPoint Presentation On Apoptosis

PPT On Apoptosis

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Apoptosis Presentation Transcript:

1. APOPTOSIS
Apoptosis means “programed cell death”. It’s role in cell population control during growth and development suggests that there are inherent cellular mechanisms that lead the cell to destruction. It is a form of cell death which is different from any other form of cell death-necrosis.

2. INTRODUCTION
Cell death by injury -Mechanical damage -Exposure to toxic chemicals Cell death by suicide -Internal signals -External signals

3. Conted…..
Apoptosis or programmed cell death, is carefully coordinated collapse of cell, protein degradation , DNA fragmentation followed by rapid engulfment of corpses by neighbouring cells. (Tommi, 2002) Essential part of life for every multicellular organism from worms to humans. (Faddy et al.,1992) Apoptosis plays a major role from embryonic development to senescence.

4. History of cell death / apoptosis
research 1800s Numerous observation of cell death 1908 Mechnikov wins Nobel prize (phagocytosis) 1930-40 Studies of metamorphosis 1948-49 Cell death in chick limb & exploration of NGF 1955 Beginning of studies of lysomes 1964-66 Necrosis & PCD described 1971 Term apoptosis coined 1977 Cell death genes in C. elegans 1980-82 DNA ladder observed & ced-3 identified 1989-91 Apoptosis genes identified, including bcl-2, fas/apo1 & p53, ced-3 sequenced (Richerd et.al., 2001)

5. Why should a cell commit suicide?
Apoptosis is needed for proper development Examples: The resorption of the tadpole tail The formation of the fingers and toes of the fetus The sloughing off of the inner lining of the uterus The formation of the proper connections between neurons in the brain Apoptosis is needed to destroy cells Examples: Cells infected with viruses Cells of the immune system Cells with DNA damage Cancer cells

6. What makes a cell decide to commit suicide?
Withdrawal of positive signals examples : growth factors for neurons Interleukin-2 (IL-2) Receipt of negative signals examples : increased levels of oxidants within the cell damage to DNA by oxidants death activators : Tumor necrosis factor alpha (TNF-) Lymphotoxin (TNF-β) Fas ligand (FasL)

7. Necrosis vs. Apoptosis
Cellular swelling Membranes are broken ATP is depleted Cell lyses, eliciting an inflammatory reaction DNA fragmentation is random, or smeared In vivo, whole areas of the tissue are affected Cellular condensation Membranes remain intact Requires ATP Cell is phagocytosed, no tissue reaction Ladder-like DNA fragmentation In vivo, individual cells appear affected

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