Final answer:
Each taste receptor cell is equipped with proteins that respond to specifically one of the five primary tastes: sweet, sour, bitter, salty, and umami. Salty and sour tastes are triggered directly by ions, while sweet, bitter, and umami tastes require the activation of G-protein-coupled receptors.
Step-by-step explanation:
Each taste receptor cell has receptor proteins that respond to one taste sensation. There are five primary tastes that humans can detect: sweet, sour, bitter, salty, and umami. Salty and sour tastes are mediated by sodium and hydrogen ions respectively, which directly affect the taste neurons. In contrast, sweet, bitter, and umami tastes involve the binding of molecules to a G-protein coupled receptor, which then initiates a series of events leading to the depolarization of gustatory cells.
Taste receptors are clustered within the taste buds on the tongue, where they interact with dissolved molecules in saliva. A single taste bud contains taste cells for all five taste sensations, allowing it to convey a full range of taste experiences to the brain. This contributes to the complexity and enjoyment of our sense of taste.