BIOL10002 Lecture Notes - Lecture 2: Semipermeable Membrane, Lipid Bilayer, Passive Transport
Document Summary
Passive transport: does not require the input of chemical energy to drive them. The energy for the passive transport of a substance comes from the difference between its concentration on one side of the membrane and its concentration on the other its concentration gradient. Active transport: requires the input of chemical energy (metabolic energy) Diffusion: process of random movement toward a state of equilibrium. The net passive movement of substances from a region of high concentration to a region of low concentration down a concentration gradient. Concentration gradient in the system - the greater the concentration gradient, the more rapidly a substance diffuses. Temperature of the solution - higher temperatures lead to faster diffusion because ions or molecules have more energy, and thus move more rapidly. Diameter of molecules or ions: smaller molecules diffuse faster. Simple diffusion: small molecules pass through the phospholipid bilayer of the membrane.