Chapter 12. Lipids and Cell Membranes Flashcards
a sterol that is an important constituent of eukaryotic membranes as well as lipoproteins; also a precursor of steroid hormones.
Cholesterol
a ceramide, common in membranes of the nervous system, in which an oligosaccharide is linked to the ceramide by a glucose residue.
Ganglioside
a sphingolipid in which glucose or galactose is linked to the terminal hydroxyl of a ceramide.
Cerebroside
sugar-containing lipids that are derived from sphingosine. The sugar moiety is attached at the alcohol on sphingosine.
Glycolipid
Phospholipids constructed on a glycerol backbone.
Phosphoglyceride
carboxylic acids containing long hydrocarbon chains that are an important fuel source as well as a key component of membrane lipids.
Fatty acid
a molecule, such as a membrane lipid, that contains both a hydrophobic and hydrophilic moiety.
Amphipathic (amphiphilic) molecule
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.
Lipid bilayer
lipid vesicles in which an aqueous region is enclosed by a lipid bilayer
Liposome
important constituents of membranes, composed of three components: a backbone (usually glycerol or sphingosine), two fatty acid chains, and a phosphorylated alcohol.
Phospholipid
the description of membranes as two-dimensional solutions of oriented lipids and globular proteins.
Fluid mosaic model
A protein that coats the cytosolic side of coated pits and can form a lattice around the pit, excising it from the membrane to form a coated vesicle.
Clathrin
An intracellular membrane vesicle that is a component of receptor-mediated endocytotic pathways. The endosome is formed when the plasma membrane in the vicinity of the cargo-receptor complex invaginates . The endosome is acidified, which causes the receptor to release its cargo. The receptor is then returned to the cell membrane.
Endosome
proteins found in membranes that interact extensively with the hydrocarbon chains of the membrane lipids and usually span the membrane.
Integral membrane protein
a sphingolipid common in brain tissue in which the terminal hydroxyl group of ceramide has a phosphorylcholine substituent.
Sphingomyelin
a means of determining transmembrane sequences in proteins by measuring the change in free energy required to move a 20-amino acid segment of the protein from a hydrophobic environment to water. The free-energy change is plotted against the position of the 20-amino acid sequence in the protein.
Hydropathy plot
proteins that are associated with the surface of membranes by electrostatic and hydrogen bond interactions.
Peripheral membrane protein
Membrane structures that result when cholesterol forms specific complexes with sphingolipids, certain glycolipids, and specific GPI-anchored proteins. These complexes concentrate within small (10-200 nm) and highly dynamic regions within membranes.
Lipid raft
the ability of lipid and protein molecules to move laterally in the membrane rapidly and spontaneously.
Lateral diffusion
a means of importing specific proteins into a cell by their binding to plasma membrane receptors and their subsequent endocytosis and inclusion into vesicles.
Receptor-mediated endocytosis
an amino alcohol containing a long, unsaturated hydrocarbon chain that is a component of the phospholipid sphingomyelin as well as glycolipids; serves a role analogous to glycerol in phosphoglycerides.
Sphingosine
A transport protein that carries iron in the blood serum.
Transferrin
(soluble N-ethylmaleimide-sensitive-factor attachment protein receptor proteins) Membrane proteins that help draw appropriate membranes together to initiate the membrane fusion process.
SNARE (soluble N-ethylmaleimide-sensitive-factor attachment protein receptor) proteins
A membrane protein that binds iron-loaded transferrin and initiates its entry into cells.
Transferrin receptor
