Diffusion, facilitated diffusion, active transport

• Diffusion - When something transfers from an area of high concentration to an area of low concentration
• Simple diffusion - Net movement of molecules from a higher concentration to a lower concentration
• Facilitated diffusion - a type of passive transport that requires a carrier protein to transport molecules across a membrane
• Carrier proteins - transport molecules that carry ions across the membrane
• Active transport - Substances move from low concentration to high concentration
• Active transport uses energy to transport molecules against their concentration gradient across a semi-permeable membrane