keep a civil tongue in one's head. Speak politely, as in The teacher won't allow swearing; she says we must keep a civil tongue in our heads. This expression uses tongue in the sense of a manner of speaking, a usage dating from the 1400s. An early cautionary version was Keep a good tongue in your head, lest it hurt your teeth (1595). See also: civil, head, keep, tongue. n. a civil servant.
Phospholipids serve a major function in the cells of all organisms: they form the phospholipid membranes that surround the cell and intracellular organelles such as the mitochondria. The cell membrane is a fluid, semi-permeable bilayer that separates the cell's contents from the environment, see animation below.hospholipids serve a major function in the cells of all organisms: they form the phospholipid membranes that surround the cell and intracellular organelles such as the mitochondria. The cell membrane is a fluid, semi-permeable bilayer that separates the cell's contents from the environment, see animation below.
Phospholipids are a class of lipids and are a major component of all cell membranes as they can form lipid bi-layers. Phospholipids are a type of large group of organic compounds called âLipidsâ.Lipids are a broad group of naturally occurring molecules with fats, waxes, fat-soluble vitamins (such as vitamins A, D, E and K), phospholipids and others.n water based solution, the phospholipids automatically arrange themselves into a double layer, or as a âphospholipid bi layerâ. The fatty acids, which repel water, are found in the middle of the bi layer.