<prompt> Last discovered taste sensation -SweetSourBitterUmami  <response>: Ans. is d i.e., Umami o Umami taste sensation is the most recent one, discovered in early 1900s.Taste sensationso There are four basic tastes namely Sweet, bitter, Salty and Sour. There mechanisms of sensory transduction are:o There are different mechanisms of sensory transduction.1 Sweet receptor is a Gprotein coupled receptor and leads to an increase in cAMP concentration in the sensory cells which results in closure of K channels and depolarization.2 Bitter receptors are also G protein coupled receptors and causes rise in intracellular Ca2 by IP3-DAG system. Rise in intracellular Ca2 triggers neurotransmitter release.3 Salty-tasti ttg substances depolarize taste cells by activating amiloride-sensitive Na channels.4 Sour-tasting substances depolarize taste cells by raising the intracellular H ion concentration, which causes closure of K channels.o The umami taste is the fifth taste which is unique. The proposed mechanism of umami taste is through glutamate taste sensors glutamate receptors with release of neuronal glutamic acid. 