BIOL 4041 Lecture 9: BIOL4041 Lecture 9: Sensory Physiology Notes 2:8
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The more receptor types you have, the better your sense of smell: humans have about 350 receptor genes and 6,000,000 olfactory receptor neurons. A lot more neurons than proteins - only one neuron expresses one receptor (highly speci c) - one receptor expressed in each cell . Not very good at using noses: dogs and rabbits signi cantly better: drosophila have 60 genes produce 62 receptors but only 32 expressed as adults. 2,600 olfactory neurons; usually one or receptor plus ubiquitous or83b (a. k. a. Olfactory receptor co-receptor - orco - if absent olfactory receptor neuron will not function; seems to make a protein dimer: c. elegans have a different strategy: 1,500 (chemosensory) but only 32 chemosensory neurons! Not understood how they can differentiate between smells. Olfactory receptors are g-protein coupled receptors (gpcr - up to 10% of all genes: 2 pathways: a channel. Cyclic amp (mammalian) - has a target on intracellular side of a protein that has.
