BIOL 2021 Lecture Notes - Lecture 8: Electrochemical Gradient, Halobacterium, Bacteriorhodopsin
19 Jan 2018
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Document Summary
Halobacterium (archaea) is stained purple and uses light as an energy source. Chromophore/retinal: part of the protein that absorbs light (similar to rhodopsin in animal photoreceptors) Absorption of light causes a conformational change in the retinal that gets transmitted to a conformational change in the protein: pumps protons out of the cell to create a membrane potential for atp synthesis and transport. Uniport: moves one ion passively (not coupled) Symport/co-transport: moves 2 ions in the same direction: one molecule moves down its concentration gradient while the other moves against its gradient, active transport, coupled. Antiport/exchange: carries 2 ions in opposite directions: one molecule moves down its concentration gradient while the other moves against its gradient, active transport, coupled. Usually an inorganic molecule is used as a coupler (ex. Na+ is usually the co-transported ion because its electrochemical gradient provides a large driving force for the active transport of a second molecule.
