<prompt> What is the type of inhibition of acetylcholinesterase caused by organophosphates?Competitive and reversibleNoncompetitive and irreversibleUncompetitive and reversibleCompetitive and irreversible  <response>: Ans. d. Competitive and irreversible Ref: Goodman Gillman 12e p242. Katzung 12e p106: KDT 7e p99The type of inhibition of acetyl cholinesterase caused by organophosphates is competitive irreversible.Organophosphates cause irreversible inhibition of Acetyl-cholinesterase while that caused by carbamates is reversible. Both bind at the esteratic site of the enzyme causing competitive inhibition. Thus, the terms reversible and irreversible as applied to the carbamoyl ester and organophosphate anti-ChE agents, respectively: reflect only quantitative differences in rates of decarbamoylation or dephosphorylation of the conjugated enzyme. Both chemical classes react covalently with the active center serine in essentially the same manner as does ACh. --Goodman Gillman 12e p242AnticholinesterasesReversibleIrreversibleCarbamatesAcridineOrganophosphateCarbamates Physostigmine Neostigmine Pyridostigmine Edrophonium Rivastigmine Donepezil Galantamine Tacrine Dyflos DFP Echothiophate Parathion Malathion Diazinon TIK -20 Tabun Sarin Soman Carbaryl Propoxur 