Transport Mechanism | Cell and subcellular organelle | Chapter 3: F.Sc. 1st Year Biology | Lec#36

3.7- MEMBRANE TRANSPORT MECHANISMS Need. The movement of substances in and out of cells is crucial for cellular functions. These movements are done for nutrient uptake, waste elimination, gas exchange, and signal transduction. Role of membrane. Cells rely on the plasma membrane for regulating the movement of substances in and out of the cell. While exchanging matter with cells’ environment, plasma membranes maintain equilibrium inside the cell as well as outside. Transport mechanisms Membrane transport mechanisms are essential processes that enable the cell to maintain homeostasis, acquire nutrients, remove waste products, and communicate with its environment. These mechanisms include two mechanisms  Passive transport (which requires no energy input)  Active transport (which utilizes energy). Passive Transport. Definition. The movement of molecules across plasma membrane without any expenditure of energy is called passive transport. The following are the types of passive transport. Diffusion. Definition. Diffusion is the net movement of a substance (liquid or gas) from an area of higher concentration to one of lower concentration i.e., along concentration gradient. Passive type. Because a cell does not expend energy when molecules diffuse across its membrane, the diffusion of molecules is a type of passive transport.