The following is an antiapoptotic gene

Ans. is 'c' i.e. Bcl-X Apoptosis is a pathway of cell death that is induced by a tightly regulated intracellular programme in which cells destined to die activate enzymes that degrade the cells own nuclear D.N.A and nuclear and cytoplasmic proteins.The cells plasma membrane remain intact but its structure is altered in such a way that apoptotic cell becomes an avid target for phagocytosis.The dead cell is rapidly cleared before its contents have leaked out, and therefore cell death by this pathway does not elicit an inflammatory reaction in the hostApoptosis occurs normally in many situations, and serves to eliminate unwanted or potentially harmful cells and cells that have outlived their usefulness.It is also a pathological event in conditions when cells are damaged beyond repair, especially when the damage affect the cell's D.N.A. In these situations the irreparably damaged cell is eliminated.How does apoptosis start ?Normally growth factors and other survival signals stimulate the production of antiapoptotic members of the Bcl-2 family of proteins.There are more than 20 proteins in this family, all of which function to regulate apoptosis.The two main antiapoptotic ones are Bcl-2 and BcL-X.These antiapoptotic proteins normally reside in the mitochondrial membranes and cytoplasm and prevents apoptosis.When cells are deprived of survival signals or subjected to stress, Bcl-2 and Bcl-X are lost from the mitochondrial membranes and are replaced by proapoptotic members o/the family such as Bak, Bax and Bim.This leads to increased permeability of mitochondrial membrane and the release of certain proteins which activate caspases which carries on the process of apoptosis.Proapoptic factorsAnti-apoptic factorsApaf-1 (Apoptosis activating factor -1)Cytochrome CBakBaxBimAIFP53 geneCaspasesTNFRIFas FADD (Fas associated death domain)BH3 only proteins (Bim, Bid, Bad)Smac/DIABLOBcl-2/BCl-X *FLIP *Mcl-1IAPs