ETYM French, from Latin membrana the skin that covers the separate members of the body, from Latin membrum. Related to Member.
1. A pliable sheet of tissue that covers or lines or connects organs or cells of animals or plants; SYN. tissue layer.
2. A thin pliable sheet of material.
The pH-sensitive glass bulb is the membrane across which the potential difference due to the formation of double layers with ion-exchange properties on the two swollen glass surfaces is developed. The membrane makes contact with and separates the internal element and filling solution from the sample solution.
In living things, a continuous layer, made up principally of fat molecules, that encloses a cell or organelles within a cell. Small molecules, such as water and sugars, can pass through the cell membrane by diffusion.Large molecules, such as proteins, are transported across the membrane via special channels, a process often involving energy input. The Golgi apparatus within the cell is thought to produce certain membranes.
In cell organelles, enzymes may be attached to the membrane at specific positions, often alongside other enzymes involved in the same process, like workers at a conveyor belt. Thus membranes help to make cellular processes more efficient.