Programmed Cell Death
Bcl2
Anti-apoptotic Bcl2 family protein of the outer mitochondrial membrane that binds and inhibits pro-apoptotic Bcl2 family proteins and prevents inappropriate activation of the intrinsic pathway of apoptosis
Executioner caspases
Apoptotic caspases that catalyze the widespread cleavage events during apoptosis that kill the cell
Intrinsic apoptosis cues
Balance of signals between anti-apoptotic factors and pro-apoptotic factors
Extrinsic apoptosis cues
Fas ligands on killer lymphocyte; Fas death receptor in target cell (related to tumor necrosis factor receptor); receptor tyrosine kinase signaling
Apoptosome
Heptamer of Apaf1 proteins that forms on activation of the intrinsic apoptotic pathway; it recruits and activates initiator caspases that subsequently activate downstream executioner caspases to induce apoptosis
Fas ligand
Ligand that activates the cell-surface death receptor, Fas, triggering the extrinsic pathway of apoptosis
Intrinsic pathway
Pathway of apoptosis activated from inside the cell in response to stress or developmental signals; depends on the release into the cytosol of mitochondrial proteins normally resident in the mitochondrial intermembrane space
Extrinsic pathway
Pathway of apoptosis triggered by extracellular signal proteins binding to cell-surface death receptors
Destruction proteins
Perform functions such as digesting proteins and DNA in a dying cell
Killer proteins
Required for a cell to begin the apoptotic process
Engulfment proteins
Required for phagocytosis of the dying cell by another cell
Cytochrome c
Soluble component of the mitochondrial electron-transport chain; its release into the cytosol from the mitochondrial intermembrane space also initiates apoptosis
T/F: Apoptosis is promoted by the release of cytochrome c from the mitochondria
True
Programmed cell death occurs ______________.
by means of an intracellular suicide program.
Apoptosis differs from necrosis in that necrosis _____________.
causes cells to swell and burst, whereas apoptotic cells shrink and condense.
Apoptosis
"Clean" cell death; DNA fragments; large vacuoles form in cytoplasm; cytoplasm collapses; cells shrink
Necrosis
"Explosive" cell death; membrane becomes dilated; cell swells; cells explode
Death-inducing signaling complex (DISC)
Activation complex in which initiator caspases interact and are activated following binding of extracellular ligands to cell-surface death receptors in the extrinsic pathway of apoptosis
Bak
A main effector Bcl2 family protein of the intrinsic pathway of apoptosis in mammalian cells that is bound to the mitochondrial outer membrane even in the absence of an apoptotic signal; activation is usually by activated pro-apoptotic BH3-only proteins
Bax
A main effector Bcl2 family protein of the intrinsic pathway of apoptosis in mammalian cells; located mainly in the cytosol and translocates to the mitochondria only after activation, usually by activated pro-apoptotic BH3-only proteins
Apoptosis and necrosis are both forms of programmed cell death. Which one of these is likely to be the mechanism for cell death in a normal developing tissue? Why?
Necrosis