Bitter Taste Essay

816 Words 4 Pages
PART A -I
As molecules reach taste receptors on the microvilli, action-potentials generated through voltage-gated channels will initiate, leading to the excitation of nerve fibres. From there, responses will be carried to the brainstem and be further processed within the brain. The information will eventually translate into taste qualities such as sweet, sour, salty, bitter and umami. Furthermore, each taste quality is specified according to the molecule that binds to the receptor.
Salt taste occurs in the presence of sodium chloride (NaCl ) along with the binding of specific minerals. It is speculated that a sodium channel acts as a receptor for salt. However, researchers are still unsure about the specific receptors that lead to the taste of salt (Chandrashekar et al., 2006). Sour taste is another quality dependent on the detection of ions. When changes in the extracellular pH occur, hydrogen (H+) ions may penetrate taste cells through their tight junctions, contributing to the sour taste (Lindemann, 2001). The PKD2L1 channel, from the TRP family has also been shown to take part in the sour taste sensing (Chandrashekar et al., 2006). Bitter taste is a response to exclusively one, or the combination of:
-a variety of bitter compounds binding to T2R G-protein receptors
-interaction
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However, glutamate alone does not provide a pleasant taste, which is characteristic of umami (McCabe and Rolls, 2007). The taste enhancing quality of umami itself is attributed to the presence of purine 5 '-ribonucleotides, found in decaying meats and other tissues. T1R1 and T1R3 (G-protein channels) taste receptors are also believed to be responsible for the umami taste (Shigemura et al., 2009). However, the perception of umami taste may be due to a result from the combination of both taste and smell (McCabe and Rolls,

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