Air pollution harms animals as a result of direct exposure to contaminants and destruction of their habitats, food and water sources. For instance, acid rain, which forms when pollutants in the... Air pollution harms animals as a result of direct exposure to contaminants and destruction of their habitats, food and water sources. For instance, acid rain, which forms when pollutants in the... Star Gazing
1 The cilia of the sensory neurons are immersed in a layer of mucus. 2  Odorant molecules (molecules that we can smell) dissolve in the mucus and. 3  bind to receptors on the cilia.4  These are 7-pass transmembrane proteins. 5  Binding of the odorant activates a G protein coupled to the receptor on its cytoplasmic side. bind to receptors on the cilia. 2  These are 7-pass transmembrane proteins. 3  Binding of the odorant activates a G protein coupled to the receptor on its cytoplasmic side. 4  This activates adenylyl cyclase, an enzyme embedded in the plasma membrane of the cilia.
Signal molecules can interact with either intracellular or extracellular receptors. For a signal molecule to bind with an intracellular receptor it must be able to pass through the cellular membrane. Generally signal molecules that enter the cell are nonpolar and fat soluble. These signal molecules can pass through the lipid bilayer of the cell membrane. Signals that bind with extracellular receptors are proteins or other types of molecules that cannot readily pass through the membrane. View the animation below, then complete the quiz to test your knowledge of the concept.