Answer to Question #309534 in Cell Biology for Seth

Question

Please explain Why do molecules move across the cell membrane?

And please also explain the importance and why it takes place.

Answer 1

This movement occurs because the molecules are constantly colliding with one another. The net movement of the molecules is away from the region of high concentration to the region of low concentration. Diffusion is a random movement of molecules down the pathway called the concentration gradient. Molecules pass through plasma membranes. Active transport maintains concentrations of ions and other substances needed by living cells in the face of these passive movements. Much of a cell's supply of metabolic energy may be spent maintaining these processes.