1.8 Cell Death Flashcards
What is apoptosis?
programmed cell death used to eliminate unwanted cells
The lack of apoptosis can lead to [ ] and [ ].
- uncontrolled cell division
- cancer
What are the four components to cell death?
- cell condenses
- cytoskeleton disassembles
- nuclear envelope breaks down
- chromatin fragments
Cell surface forms protrusions called [ ].
blebs
Fragmentation typically occurs to allow [ ] to better [ ] the cell.
- macrophages
- engulf
Why is it important for an apoptotic cell to be engulfed by macrophage?
- allow death of cell to be neat. Cellular contents are easly cleared away
- prevents damaging inflammatory responses
What is necrosis?
Non-apoptotic way for damaged cells to die
A common and passive form of necrosis is [ ] in response to tissue trauma
cell lysis
The release of celular contents into surround environment causes [ ].
inflammatory response
What are the four functions of apoptosis?
- allows for shaping of appendages
- kills cells of structures that are no longer needed
- kills abnormal or non-functional cells
- balances cell division in tissues that are maintaining relatively constant mass
What is the function of caspase?
intracellular protease that are apoptosis by cleaving specific target proteins
What is the composition of caspase?
have a cysteine (c) residue in their active site that is used to cleave their targets at specific aspartic (asp) residues. C + Asp + enzyme = Caspase
What are the two major classes of apoptotic caspases?
- initiator caspases
- excutioner caspases
What is the function of initiator caspases?
begins apoptosis. In mammals, these are caspase-8 and caspase-9
Initiator caspses exist in cytosol as [ ], soluble monomers ([ ]). These contain a [ ].
- inactive
- procaspase
- prodomain
What is the function of executioner caspases?
coordinate apoptosis. In mammals, these are caspase-3, caspase-6, and caspase-7
What is the caspase cascade?
each initiator can amplify the apoptotic signal by activating multiple executioners
Caspase signaling is [ ] and [ ].
self-amplifying and irreversible
An example of an executioner caspase target are the [ ], which make up the nuclear cytoskeleton (intermediate filaments).
nuclear lamins
What are the two main pathways of initiator activation?
- intrinsic pathway (mitchondrial pathway)
- extrinsic pathway
Extrinsic pathway is activated by extracellular apoptotic signals binding to [ ].
cell-surface death receptors
What do death receptors contain?
- extracellular ligand-binding domain
- transmembrane domain
- intracellular death domain
What are the receptors of apoptosis?
homodimers belonging to tumor necrosis family (TNF) receptor family. Includes the Fas ligand.
TNF receptors bind ligands from the [ ].
TNF family of signal proteins
Fas signaling plays a role in regulating number of [ ].
T and B lymphocytes
The intrinsic pathway depends upon the [ ] into the cytosol.
release of mitochondrial proteins
Signal molecules normall reside in [ ] (intrinsic pathway).
intermembrane space
Most important of these signals is [ ] of the electron transport chain (intrinsic pathway).
cytochromc C
What is the function of Bcl2 family of proteins?
regulate the intrinsic pathway by controlling permeabilization of the outer mitochondrial membrane
What are the three functional and structural classes of Bcl2 proteins?
- anti-apoptotic Bcl2
- pro-apoptotic Bcl2
- BH3-only proteins
What is the function of anti-apoptotic Bcl2?
inhibits apoptosis by preventing mitochondrial outer membrane permeabilization (MOMP)
What is the function of pro-apoptotic Bcl2?
creates openings in outer membrane to induce MOMP and promotes apoptosis
What is the function of BH3-only proteins?
pro-apoptotic. Regulates the two classes above
What is the function of inhibitors of apoptosis proteins (IAPs)?
protect against inappropriate apoptosis by inhibiting caspase enzymes (caspase-9 and caspase-3, caspase-7)
Mammals have one type of IAPs ([ ]) that is encoded on the X chromosomes.
XIAP
Survival factors are [ ].
extracellular signals that inhibit apoptosis
Survival factors bind to [ ] that inhibit [ ].
- cell surface receptors
- the apoptotic pathway
What are the three functions of survival factors?
- regulate the expression or activity of Bcl2 family of proteins
- promote synthesis of anti-apoptotic Bcl2 proteins
- inhibit pro-apoptotic BH3-only proteins
