BIO E105 Lecture Notes - Lecture 19: Active Transport, Electrochemical Gradient, Passive Transport
Document Summary
Land animals constantly lose water to the environment, just as many marine animals do, but they lose it by evaporation rather than osmosis. Land animals also lose water when they produce urine and when they sweat or pant. The loss of water is replaced by drinking, by ingesting water from food, or by metabolic pathways. Lose water from other parts of body to evaporation. Solutes move across membranes by passive or active transport. Passive transport is driven by diffusion along an electrochemical gradient and does not require an expenditure of energy in the form of atp. Facilitated diffusion is passive transport of solutes via proteins called channels or carriers. Active transport occurs when atp powers the movement of a solute against its electrochemical gradient. Membrane proteins (b) active transport requires an energy source to move molecules against a gradient. Secondary active transport (cotransport; driven by (driven by energy from atp) energy from gradient)
