Transport

• Molecules can be transported in and out of the cell through passive and active transport methods
• Passive transport: no extra energy used by the cell, includes diffusion and osmosis, small non-polar molecules phase through the plasma membrane unassisted, larger charged molecules travel via facilitated diffusion using protein channels or carrier proteins
• Small non-polar molecules includes oxygen, carbon dioxide and water
• Larger charged molecules include glucose, amino acids and ions
• Diffusion: particles spontaneously move from high concentration areas to low concentration areas following the concentration gradient, the exchange occurs across a moist cell membrane, efficiency is affected by surface area and membrane thickness
• Osmosis: diffusion specifically for water molecules moving across a semipermeable membrane, water moves from an area of low solute concentration to an area of higher solute concentration, hypertonic = a solute with a higher solute concentration than another, isotonic = a solute with a balanced solute concentration with another, hypotonic = a solute with a lower solute concentration than another
• Active Transport: process of moving molecules across the cellular membrane against the concentration gradient through the use of cellular energy, called primary active transport when powered by adenosine triphosphate (ATP), active transport used by cells to accumulate needed molecules like glucose and amino acids
• Main Methods of Active Transport: ion pumps, endocytosis (transport in), exocytosis (transport out)