What is Membrane?
A '''membrane''' is a thin soft layer of material. A membrane separates two things. In [[biology]] a membrane can mean two things: a tissue membrane or the membranes of a [[cell]]. The membranes of cells are very small, while tissue membranes are larger. ==Tissue membranes== A membrane can mean a thin layer of [[cell]]s or [[Tissue (biology)|tissue]]. This layer covers the body or an organ, or separates, or lines a body [[cavity]]. An example is the [[mucous membrane]] that is the ''skin'' that lines the inside of your nose and mouth. An epithelial membrane has two parts, one part is [[epithelial tissue]] and the other is [[connective tissue]]. ==Membranes of cells== [[Image:Cell membrane drawing-en.svg|thumb|upright=1.2|A [[cell membrane]] is a double layer of [[Lipid bilayer|phospholipid]] with proteins in it and attached to it.]] There are many different types of membranes in a cell. The [[cell membrane]], also called the plasma membrane, covers one cell. Membranes also divide the cell into different spaces called [[organelle]]s. Organelles are special areas of the cell that do different work. For example, the [[Cell nucleus|nucleus]] holds the [[DNA]] in a cell. The [[mitochondria]] make [[energy]] for the cell. Membranes in cells are made of [[lipid]]s (fats) and [[protein]]. The lipids keep the inside of the cell or the organelle separate from the outside. The proteins do many things. Plasma membranes give the cell messages from outside. They let some things (like [[glucose]], [[calcium]], and [[potassium]]) go into and out of the cell. {{science-stub}} [[Category:Cell biology]] [[Category:Plant anatomy]]