Final answer:
The amino acid serine in acetylcholinesterase is targeted by diisopropyl fluorophosphate, which inhibits the enzyme and affects nerve impulse transmission.
Step-by-step explanation:
The amino acid in acetylcholinesterase that is targeted by diisopropyl fluorophosphate (DIPF) is serine. DIPF, an organophosphate insecticide, forms a covalent bond with the hydroxyl (-OH) group of a serine residue within the enzyme's active site. Acetylcholinesterase is crucial for nerve impulse transmission as it catalyzes the reaction that breaks down the neurotransmitter acetylcholine. The binding of DIPF to serine in acetylcholinesterase prevents the breakdown of acetylcholine, resulting in the accumulation of acetylcholine in the synapse and the subsequent overstimulation of the postsynaptic membrane, leading to paralysis.