Transport There are two types of transport that occur between cells: passive and active transport. Passive Transport - Molecules naturally move from an area of high concentration to low concentration. This does not use energy. There are 3 types of passive transport: simple diffusion , facilitated diffusion , and osmosis . - Simple Diffusion: Small and nonpolar molecules more from an area of high to low concentration. If there is more than one solute, then those solutes will be equally distributed across a membrane. These molecules will be able to easily pass through the membrane, which is why it's called simple diffusion: nothing is needed to help it pass through. - Facilitated Diffusion: Polar molecules and ions impeded by the bilayer of the membrane are diffused passively with the help of transport proteins spanning the membrane. Diffusion will occur through protein channels. Again, it moves from high concentration to low...
Welcome! The information here can help anyone who wants to learn biology, whether it be high school biology or AP level biology. If you don't already know some basic chemistry, learn that first! A lot of stuff in the biochemistry topic builds on chemistry, so knowing it beforehand will help when going through these topics. Comment for any questions! And most of all, have fun learning biology :)