BISC306 Lecture Notes - Lecture 12: Taste Receptor, Umami, Cytosol
5 Oct 2016
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Gustatory & olfactory senses: gustation-tasting sense, chemosensation-chemical senses, papillae-taste bud type cells b. i. Able to distinguish 4,000-10,000 chemicals: 5 primary taste qualities: bitter, sour, sweet, salt, umami c. i. Salt channel is always open; neurotransmitter always releases. [na+] must be 50 mm or greater to taste salty. Bitter, sweet, and umami-use g-protein coupled receptors (metabotropic receptors) c. iii. 1. Sweet receptors-receptors bind sugars & some amino acids; some sweeteners like aspartame are 1000s of times sweeter than sugar c. iii. 2. Umami receptors-receptors bind to different amino acids including glutamate c. iii. 3. Bitter receptors-receptors warn of poisons; about 30 different receptors and individual receptor cells have most or all of them; so animals are not good at distinguishing between different bitter tastes c. iii. 4. G-protein is activated, calcium concentration in cytosol rises, and open. Taste cells-seem to have only one type of taste receptor a nerve may be stimulated by more than one taste: chemoreceptors-different tasting receptor cells d. i.
