Flashcards in Chapter 6 Deck (36):
Containing hydrophilic and hydrophobic regions.
A type of channel protein through which water can move by osmosis across a plasma membrane.
A membrane protein that facilitates diffusion of a small molecule (e.g., glucose) across a membrane by a process involving a reversible change in the shape of the protein. Also called carrier or transporter. Compare with channel protein.
A protein that forms a pore in a cell membrane. The structure of most channels allows them to admit just one or a few types of ions or molecules. Compare with carrier protein.
Difference across space (e.g., across a membrane) in the concentration of a dissolved substance.
A type of small amphipathic molecule used to solubilize hydrophobic molecules in aqueous solution.
Spontaneous movement of a substance from one region to another, often with a net movement from a region of high concentration to one of low concentration (i.e., down a concentration gradient).
The covalent bond formed by a condensation reaction between a carboxyl group and a hydroxyl group. Ester linkages join fatty acids to glycerol to form a fat or phospholipid.
Passive movement of a substance across a membrane with the assistance of transmembrane carrier proteins or channel proteins.
A lipid consisting of three fatty acid molecules joined by ester linkages to a glycerol molecule. Also called triacylglycerol or triglyceride.
A lipid consisting of a hydrocarbon chain bonded at one end to a carboxyl group. Used by many organisms to store chemical energy; a major component of animal and plant fats and phospholipids.
The widely accepted hypothesis that the plasma membrane and organelle membranes consist of proteins embedded in a fluid phospholipid bilayer.
A channel protein that opens and closes in response to a specific stimulus, such as the binding of a particular molecule or a change in voltage across the membrane.
A three-carbon molecule that forms the "backbone" of phospholipids and most fats.
An organic molecule that contains only hydrogen and carbon atoms.
Comparative term designating a solution that, if inside a cell or vesicle, results in the uptake of water and swelling or even bursting of the membrane-bound structure. This solution has a greater solute concentration than the solution on the other side of the membrane. Used when the solute is unable to pass through the membrane. Compare with hypotonic and isotonic.
Comparative term designating a solution that, if inside a cell or vesicle, results in the loss of water and shrinkage of the membrane-bound structure. This solution has a lower solute concentration than the solution on the other side of the membrane. Used when the solute is unable to pass through the membrane. Compare with hypertonic and isotonic.
Integral membrane protein
Any membrane protein that spans the entire lipid bilayer. Also called transmembrane protein. Compare with peripheral membrane protein.
Comparative term designating a solution that, if inside a cell or vesicle, results in no net uptake or loss of water and thus no effect on the volume of the membrane-bound structure. This solution has the same solute concentration as the solution on the other side of the membrane. Compare with hypertonic and hypotonic.
Any organic substance that does not dissolve in water, but dissolves well in nonpolar organic solvents. Lipids include fatty acids, fats, oils, waxes, steroids, and phospholipids.
The basic structural element of all cellular membranes; consists of a two-layer sheet of phospholipid molecules with their hydrophobic tails oriented toward the inside and their hydrophilic heads toward the outside. Also called phospholipid bilayer.
An unsaturated fat that is liquid at room temperature.
Diffusion of water across a selectively permeable membrane from a region of low solute concentration (high water concentration) to a region of high solute concentration (low water concentration).
Diffusion of a substance across a membrane. When this event occurs with the assistance of membrane proteins, it is called facilitated diffusion.
Peripheral membrane protein
Any membrane protein that does not span the entire lipid bilayer and associates with only one side of the bilayer. Compare with integral membrane protein.
The tendency of a structure, such as a membrane, to allow a given substance to diffuse across it.
A class of lipid having a hydrophilic head (including a phosphate group) and a hydrophobic tail (consisting of two hydrocarbon chains). Major components of the plasma membrane and organelle membranes.
A membrane that surrounds a cell, separating it from the external environment and selectively regulating passage of molecules and ions into and out of the cell. Also called cell membrane.
A hypothetical pre-cell structure consisting of a membrane compartment that encloses replicating macromolecules, such as ribozymes.
Referring to lipids in which all the carbon-carbon bonds are single bonds. Such compounds have relatively high melting points. Compare with unsaturated.
Scanning electron microscope (SEM)
A microscope that produces images of the surfaces of objects by reflecting electrons from a specimen coated with a layer of metal atoms. Compare with transmission electron microscope.
Secondary active transport
Transport of an ion or molecule in a defined direction that is often against its electrochemical gradient, in company with an ion or molecule being transported along its electrochemical gradient. Also called cotransport.
The property of a membrane that allows some substances to diffuse across it much more readily than other substances.
A class of lipid with a characteristic four-ring hydrocarbon structure.
Referring to lipids in which at least one carbon-carbon bond is a double bond. Double bonds produce kinks in hydrocarbon chains and decrease the compound's melting point. Compare with saturated.