Biology Basics: Homeostasis

Homeostasis 1. What is diffusion? What is osmosis? Diffusion is the process by which substances spread from regions of high concentration to regions of low concentration. It is a method of passive transport, and thus costs the cell no energy. Electrically charged ions and large molecules will not diffuse freely across the membrane. Facilitated diffusion is used for molecules that can't diffuse through the cell membrane because they are too large or not soluble in the …

…cell b. Pinocytosis- movement of solutes of fluids into cell -Exocytosis: passage of large molecules out of the cell -Sodium-Potassium Pump- 3 sodium ions (Na+) fit into carrier protein and are moved out of cell, 2 potassium ions (K+) fit into carrier protein and are moved into cell; occurs in creation of electrical gradient, + outside, - inside cell -Proton Pump- transports protons (H+ less the electron) across membranes of mitochondria and chloroplasts; used to make ATP (chemiosmosis).