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Chapter 7 Membrane Structure and Function
Life at the Edge.
Terms in this set (30)
a process in which a membrane allows some molecules to pass through while keeping others out
fluid mosaic model
structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer, The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individually inserted protein molecules drifting laterally in a fluid bilayer of phospholipids.
cell membrane components
Phospholipids (75%), glycolipids (5%), and cholesterol (20%) ., made up of phospholipids(lipid bilayer) and membrane proteins, phospholipid bilayer with embedded proteins, or a fluid mosaic of proteins, which is semi-permeable
Molecules that are constituents of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.
The property by which most of the plasma membrane lipids and proteins easily rotate and move side ways in their own half of the lipid bilayer. THis property allows the membrane to self seal if torn; proteins seldom flip-flop from one half of the bilayer to to the other., determined by % of unsaturated fatty acids in phospholipids (more unsaturated chains, more fluid);
Composition and distribution of cholesterol in membrane (more cholesterol, more rigid);
Lipid flipping is rare, but membrane proteins NEVER flip
Functions of membrane proteins
transport, receptor site, cell-to-cell recognition, attachment of the cytoskeleton components
proteins that penetrate through the membrane...contained in the eukaryotic and prokaryotic phospholipid bilayers
occurs mostly in ER w/ modifications in Golgi Apparatus
transport of membrane "pieces" occur in vesicles - inner face of vesicle become outer face, Eukaryotes, cytosol and endomembrane system work together to synthesize most lipids. Process occurs at cytosolic leaflet of smooth ER. Fatty acids building blocks madevia enzymes in cytosol, taken into cells from food
a difference in the concentration of a substance across a distance, the path molecules travel when an imbalance between separated molecule concentrations exists
Protein appendages loosely bound to the surface of the membrane and not embedded in the lipid bilayer.
the process by which molecules move from an area of higher concentration to an area of lower concentration
The movement of materials through a cell membrane without using energy(diffusion)
movement from a high concentration area to a low concentration area, only works with oily substances, needs to cross oily cell membrane (nonpolar substances), no energy is required
diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal
(used of solutions) having the same or equal osmotic pressure (two solutions have the same concerntration/temp)
when comparing two solutions, the solution with the lesser concentration of solutes, (of a solution) having a lower osmotic pressure than a comparison solution
when comparing two solutions, the solution with the greater concentration of solutes, (of a solution) having a higher osmotic pressure than a comparison solution
the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins
A membrane protein that forms a channel or pore completely through the membrane and that is usually permeable to one or to a few water-soluble molecules, especially ions.
a protein that transports substances across a cell membrane, a membrane protein, specifically a transport protein, that holds onto molecules and changes their shapes in a way that shuttles them across the membrane
transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient, energy-requiring process that moves material across a cell membrane against a concentration difference
The diffusion gradient of an ion, which is affected by both the concentration difference of the ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force).
Sodium Potassium pump
a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell., Cotransporter that actively moves sodium out of a cell and passively moves potassium into it.
A protein found in the plasma membrane of all cells in the body that uses the energy of an ATP (hydrolyzes ATP) to move three Na+ ions out of the cell and two K+ ions into the cell, thus establishing concentrations gradients for these ions across the cell membrane.
The difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances., The charge difference between a cell's cytoplasm and the extracellular fluid, due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances.
An ion transport protein that generates voltage across a membrane.
An active transport mechanism in cell membranes that uses ATP to force hydrogen ions out of a cell, generating a membrane potential in the process.
a single ATP powered pump that transports one solute can indirectly drive the active transport of several other solutes in this mechanism as the solute that has been actively transported diffuses back passively through a transport protein its movement can be coupled with the active transport of another substance against its concentration gradient
Amphipathic molecules have both hydrophobic regions and hydrophilic regions <phospholipids>.
Capable of generating an electrical current; usually applied to membrane transporters that create electrical currents while translocating ions.
THIS SET IS OFTEN IN FOLDERS WITH...
Cell Wall And Plasma Membrane
Chapter 6 A Tour of the cell
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