Download Cell Death Process

BIOLOGI - ACHADIAH RACHMAWATI
Cell Death Process
Programmed Cell Death
in Eukaryotes
• Cell death can occur by either of two distinct mechanisms –
apoptosis or necrosis.
• Apoptosis: originally defined according to a set of
characteristic ultrastructural features that include nuclear and
cytoplasmic condensation, cell fragmentation and
phagocytosis.
• Necrosis: cell death as the result of injury, disease, or
pathological state (usually involves large numbers of cells and
is associated with inflammation). Chromatin condenses in
multiple small clumps and at later stages, cell membranes
and organelles disintegrate.
Achadiah Rachmawati
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Why should a cell commit suicide?
Programmed Cell Death
in Eukaryotes
Apoptosis is needed for proper development
– 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
– Cells infected with viruses
– Cells of the immune system
– Cells with DNA damage
– Cancer cells
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BIOLOGI - ACHADIAH RACHMAWATI
Classical View of Cell Death:
Apoptosis vs Necrosis
Necrosis vs. Apoptosis
Necrosis
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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
Apoptosis
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Cellular condensation
Membranes remain intact
Requires ATP
Cell is phagocytosed, no
tissue reaction
• Ladder-like DNA
fragmentation
• In vivo, individual cells appear
affected
Murder?
Suicide?
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Stages of Apoptosis
NECROSIS vs. APOPTOSIS
Induction of apoptosis related genes, signal transduction
Wilde, 1999
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BIOLOGI - ACHADIAH RACHMAWATI
Biological Roles for Apoptosis
Apoptosis in Development
• Development
• Metamorphosis
• Regulation of cell number in
tissues (homeostasis and
tumorigenesis)
• Immune defense (cytotoxic T
cell activity)
• Develoment of B and T cells
via negative selection
• Disease: Cancer,
autoimmunity, infectious
disease etc.
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Definitions
• Hyperplasia → Number of cells
– Prostate
– Endometrium
– Breast ducts
• Hypertrophy → SIZE of cells
– Myocardium
– Muscle fibres
• Metaplasia → Change of cell TYPE
– Cervical where glandular → squamous epithelium
– Bronchioles where glandular → squamous epithelium
• Dysplasia → Abnormal Development, size, shape,
arrangement
– Cervical
– fibrous
Tumour, metastasis, carcinogen
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CELL DEATH PROCESS
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