![]() ![]() In simple diffusion, this process proceeds without the aid of a transport protein. The kinetic energy of the molecules results in random motion, causing diffusion. The difference in the concentrations of the molecules in the two areas is called the concentration gradient. For cell transport, diffusion is the movement of small molecules across the cell membrane. Facilitated diffusion requires the assistance of proteins.ĭiffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. Simple diffusion and osmosis do not involve transport proteins. The three main kinds of passive transport are diffusion (or simple diffusion), osmosis, and facilitated diffusion. Passive transport is a way that small molecules or ions move across the cell membrane without input of energy by the cell. Animal cells tend to do best in an isotonic environment, where the flow of water in and out of the cell is occurring at equal rates. ![]() When placed in a hypertonic solution, a red blood cell will lose water and undergo crenation (shrivel). Cells placed in a hypotonic solution will take in water across their membranes until both the external solution and the cytosol are isotonic.Ī red blood cell will swell and undergo hemolysis (burst) when placed in a hypotonic solution.If a cell is in a hypertonic solution, the solution has a lower water concentration than the cell cytosol, and water moves out of the cell until both solutions are isotonic.Water moves into and out of cells by osmosis. Osmosis is the diffusion of water molecules across a semipermeable membrane from an area of lower concentration solution (i.e., higher concentration of water) to an area of higher concentration solution (i.e., lower concentration of water). ![]() \): Red blood cells in hypertonic, isotonic, and hypotonic solutions. ![]()
0 Comments
Leave a Reply. |