Passive Transport | Structure and Function of Plasma Membranes | Unit 2. The Cell

Chapter: Passive Transport Collection: Structure and Function of Plasma Membranes Unit 2. The Cell Book: Biology Read the 'Passive Transport' chapter online at: https://www.jobilize.com/biology/cour... Check your comprehension by answering those online MCQ questions: https://www.jobilize.com/biology/mcq/... The passive forms of transport, diffusion and osmosis, move materials of small molecular weight across membranes. Substances diffuse from areas of high concentration to areas of lower concentration, and this process continues until the substance is evenly distributed in a system. In solutions containing more than one substance, each type of molecule diffuses according to its own concentration gradient, independent of the diffusion of other substances. Many factors can affect the rate of diffusion, including concentration gradient, size of the particles that are diffusing, temperature of the system, and so on. In living systems, diffusion of substances into and out of cells is mediated by the plasma membrane. Some materials diffuse readily through the membrane, but others are hindered, and their passage is made possible by specialized proteins, such as channels and transporters. The chemistry of living things occurs in aqueous solutions, and balancing the concentrations of those solutions is an ongoing problem. In living systems, diffusion of some substances would be slow or difficult without membrane proteins that facilitate transport. 00:00 Passive Transport 01:48 Selective permeability 04:21 Diffusion 05:49 Factors that affect diffusion 10:11 Facilitated transport 11:29 Channels 13:35 Carrier proteins 16:08 Osmosis 16:50 Mechanism 19:11 Tonicity 20:45 Hypotonic solutions 21:41 Hypertonic solutions 22:06 Isotonic solutions 22:38 Art connection 22:56 Tonicity in living systems 27:27 Section summary Download for free at https://openstax.org/details/books/bi.... ©Copyright 2022 Jobilize LLC all rights reserved.