Apoptosis Flashcards
Is apoptosis ATP dependent?
Yes (hopefully you memorized this by now…)
What are the morphological changes in cells that are undergoing apoptosis?
Cell shrinks and cytoplasm is more eosinophilic. Nucleus condenses and fragments in an organized manner. Apoptotic bodies are removed by macrophages
What is the role of proteases and endonucleases in apoptosis?
Proteases break down cytoskeleton, endonucleases break down DNA
What are apoptotic bodies?
Membrane encased structures containing cytoplasm, densely-packed organelles and fragments of nuclei.
What happens to the plasma membrane in apoptosis?
It remains intact but has blebbing and reversal of lipid asymmetry
What is the intrinsic pathway of apoptosis?
Cellular injury (or other stimuli) leads to inactivation of Bcl2. Bcl2 is the guardian of the inner mitochondrial matrix and so without Bcl2, cytochrome C can leak out and activate caspases
What are the cellular features of necrosis and how do they differ from apoptosis?
In necrosis, the nuclei condense (pyknosis) and fragment and lysis (karyolysis); the cell and its organelles rupture (plasma membrane burst) and it generates an acute inflammatory response. Apoptosis is more organized, no lysing of plasma membrane, and the cells are phagocytized, generating no inflammatory response.
What is the extrinsic pathway of apoptosis?
Aka the death receptor pathway. FAS ligands bind FAS death receptors (CD95) activating caspases.
What is the apoptotic pathway by which negative selection of thymocytes occurs?
via death receptor pathway (extrinsic) with the FAS receptor and FAS ligand binding
What are the two receptors that act via the extrinsic pathway to cause apoptosis?
FAS receptor and the TNF receptor. Both of these receptors activate caspases
What is the difference between microautophagy and macroautophagy?
Microautophagy occurs via direct engulfment of cytoplasmic material via lysosomal invaginations. Macroautophagy occurs via the autophagosome which fuses with the lysosome to make the autolysosome
Which caspases are the initiator caspases? Which are the executioner caspases?
Caspases 8 and 10 are initiators; 3,6 and 7 are executioner caspases
How does caspase 3 cause apoptosis?
Caspase cleaves an inhibitor of caspase-activated DNAase (called inhibitor of caspase-activated DNAase or I-CAD), so the DNAase (CAD) is free to enter nucleus and cleave DNA
Why is cytochrome C a proapoptotic factor?
it associates with Apaf-1 and procaspase 9 to form apoptosome which leads to activation of caspase 9 -> activator of caspase 3
What are the two pro-apoptotic genes?
BAX and BAK
