Chapter 12: Lipids and Biological Membranes

Exam 3

lipids

Water-insoluble biomolecules that are highly soluble in organic solvents

fatty acids

A carboxylic acid that contains a long hydrocarbon chain

phospholipid

An important constituent of membranes that is composed of three components: a backbone (usually glycerol or sphingosine), two fatty acid chains, and a phosphorylated alcohol

phosphoglyceride

phospholipids derived from glycerol

sphingomyelin

a sphingolipid in which the terminal hydroxyl group of ceramide has a phosphorylcholine substituent

sphingosine

An amino alcohol containing a long, unsaturated hydrocarbon chain that is a component of the phospholipid sphingomyelin and of glycolipids

glycolipid

A sugar-containing lipid that is derived from sphingosine

cholesterol

A sterol that is an important constituent of eukaryotic membranes and lipoproteins

amphipathic molecule

A molecule, such as a membrane lipid, that contains both a hydrophobic and a hydrophilic moiety

micelle

A globular structure, typically formed from free fatty acids that contain only one hydrocarbon chain, in which the polar head groups form the outside surface and the hydrocarbon tails are sequestered inside

lipid bilayer

A bimolecular sheet formed by amphipathic molecules in which the hydrophobic moieties are on the inside of the sheet and the hydrophilic ones are on the aqueous outside

liposome (lipid vesicle)

An artificial membrane structure that consists of an aqueous compartment enclosed by a lipid bilayer

integral membrane protein

A protein found in membranes that interacts extensively with the hydrocarbon chains of the membrane lipids and usually spans the membrane

peripheral membrane protein

A protein that is associated with the surface of a membrane by electrostatic and hydrogen-bond interactions

lateral diffusion

The ability of lipid and protein molecules to move laterally in the membrane rapidly and spontaneously

fluid mosaic model

A model that describes the overall organization of biological membranes as two-dimensional solutions of oriented lipids and globular proteinsComplexes that are formed by cholesterol and some phospholipids

lipid rafts

Complexes that are formed by cholesterol and some phospholipids

gram staining

A method for staining bacteria using crystal violet that can distinguish between bacteria that possess a single membrane and a thick cell wall (Gram positive), and those that have a double lipid bilayer (Gram negative)