All of the following are true about apoptosis excep:
Ans: c (Smeared pattern of DNA fragmentation) Ref: Robbins, 7th ed, p. 27Smeared pattern of DNA fragmentation is indicative of necrosis and ladder pattern of DNA fragmentation on electrophoresis is indicative of apoptosisMorphological features of apoptosis:1) Cell shrinkage2) Chromatin condensation - most characteristic feature3) Formation of cytoplasmic blebs and apoptotic bodiesApoptotic bodies are round or oval bodies with eosinophilic cytoplasamand dense chromatin fragments4) Phagocytosis of apoptotic cells by macrophagesMechanism of apoptosis:Extrinsic pathway ot ApoptosisFas ligand|Binds with three molecules of FAS|Forms binding site for FAS associated death domain|FADD(Fas associated death domain binds)|Activation of caspases 8( Caspases 10 in humans)|Activation of execution caspases (3,6)|APOPTOSISIntrinsic pathwayWithdrawal of growth hormone/stress or injury|Loss of BCL 2,BCL-XL (antiapoptotic)Accumulation of Bax ,Bim, Bid etc.|Increasing permeability of mitochondrial membrane and leakage of proteins|||cytochrome cApoptosis inducing factor||Activation of caspases 9Neutralisation of inhibitor of Apoptosis|||Activation of execution caspases (3,6)|APOPTOSISDifference between necrosis and apoptosisFeatureNecrosisApoptosisNucleusPyknosis,Karyorrhexis,KaryolysisFragmentation into nucleosomePlasma membraneDisruptedIntactCellular contentsEnzymatic digestion - contents may leak out of cellIntact; released as apoptosisAdjacent inflammationFrequentNilPhysiological/ pathologicalAlways pathologicalOften physiologicImportant points regarding apoptosis:Best known death receptor - TNF 1 receptor (TNFR1) and a related protein called FAS (CD 95)Apoptotic cells express phosphatidyl serine and thrombospondin on their surfaceTumor marker of apoptosis - Annexin 5Intermediate molecule between death receptor andcaspases - SphingolipidceramideBRIDGEPyroptosis: Programmed cell death associated with antimicrobial responses during inflammation. It is studied in the context of Salmonella infected macrophages
Expression of caspases
Internucleosomal cleavage of DNA
"Smeared" pattern of DNA fragmentation
Expression of phosphatidyl serine
Cellular Pathology