Chapter 11, Problem 13TYU

SYNTHESIZE YOUR KNOWLEDGE

There are five basic tastes—sour, salty, sweet, bitter, and "umami." Salt is detected when the concentration of salt outside of a taste bud cell is higher than that inside of it, and ion channels allow the passive leakage of Na⁺ into the cell. The resulting change in membrane potential (seeConcept 7.4) sends the "salty" signal to the brain. Umami is a savory taste generated by glutamate (glutamicacid, found in monosodium glutamate, or MSG), which is used as a flavor enhancer in foods such as taco-flavored tortilla chips. The glutamate reeeptor is a GPCR, which, when bound, initiates a signaling pathway that ends with a cellular response, pereeived by you as "taste." If you eat a regulär potato chipand then rinse your mouth, you will no longer taste salt. But if you eat a flavored tortilla chip and then rinse, the taste persists. (Try it!) Proposea possiblc explanation for this difference.