Fluoride ion is commonly used in drinking water supplies and in toothpaste (in the form of sodium fluoride) to prevent tooth decay The fluoride ions replace hydroxide ions in the enamel mineral hydroxyapatite [Ca5(PO4)3F. the same mineral as in bone], forming fluoroapatitc [Ca5(PO4)3F]. Why does replacing the hydroxide ion with fluoride ion prevent tooth decay? How does this relate to the properties of materials used in artificial fillings?
Wednesday, September 21, 2016 Bio 1020 Facilitated Diffusion: Passive Transport Aided by Proteins - In facilitated diffusion, transport proteins speed the passive movement of molecules across the plasma membrane - Channel proteins provide corridors that allow a speciﬁc molecule or ion to cross the membrane - Channel Proteins include • Aquaporins, for facilitated diffusion of water • Ion channels that open or close in response to a stimulus (gated channels) - Passive transport = no energy input required - Tonicity affects passivity of transport - Active transport uses energy to move solutes against their gradients - Facilitated diffusion is still passive bc the solute moves down its concentration gradient and the transport requires no energy - Some transport prote