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| 7680200724 | amphipathic molecule | has both a hydrophilic region and a hydrophobic region. Includes phospholipids and most proteins within membranes. | 0 | |
| 7680201715 | fluid mosaic model | the membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer (bilayer) of phospholipids. | 1 | |
| 7680204145 | cholesterol | At relatively high temperatures, makes the membrane less fluid by restraining phospholipid movement. Hinders the close-packing of phospholipids. Lowers the temperature required for the membrane to solidify. Can be thought of as a "fluidity buffer" for the membrane, resisting changes in membrane fluidity that can be caused by changes in temperature. | 2 | |
| 7680202946 | integral proteins | penetrate the hydrophobic interior of the lipid bilayer. The hydrophobic regions of this consist of one or more stretches of nonpolar amino acids, usually coiled into alpha helices. Some proteins also have a hydrophilic channel through their center that allows the passage of hydrophilic substances. | 3 | |
| 7680213696 | peripheral proteins | not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins. | 4 | |
| 7680215074 | six major functions of plasma membrane proteins | 1) Transport 2) Enzymatic activity 3) Signal transduction A membrane protein (receptor) may have a binding site with a specific shape that fits the shape of a chemical messenger, such as a hormone. The external messenger (signaling molecule) may cause the protein to change shape, allowing it to relay the message to the inside of the cell, usually by binding to a cytoplasmic protein. 4) Cell-cell recognition 5) Intercellular joining 6) Attachment to the cytoskeleton and extracellular matrix (ECM) | 5 | |
| 7680218040 | glycolipids | carbohydrates that are covalently bonded to lipids | 6 | |
| 7680218618 | glycoproteins | carbohydrates bonded to proteins | 7 | |
| 7680222435 | transport proteins | span the membrane and allow hydrophilic substances to avoid contact with the lipid bilayer | 8 | |
| 7680223109 | aquaporins | channel proteins that allow the transport of water through a membrane. | 9 | |
| 7680223822 | carrier proteins | hold onto their passengers and change shape in a way that shuttles them across the membrane. They alternate between two shapes, moving a solute across the membrane during shape change. | 10 | |
| 7680225924 | concentration gradient | the region along which the density of a chemical substance increases or decreases. represents potential energy and drives diffusion. | 11 | |
| 7680229518 | osmosis | the diffusion of free water across a selectively permeable membrane | 12 | |
| 7680230028 | tonicity | the ability of a surrounding solution to cause a cell to gain or lose water. The tonicity of a solution depends in part on its concentration of solutes that cannot cross the membrane (nonpenatrating solutes) relative to that inside the cell. Water will flow to where there are more nonpenetrating solutes. | 13 | |
| 7680231707 | osmoregulation | the control of solute concentrations and water balance. | 14 | |
| 7680233418 | facilitated diffusion | when molecules impeded by the lipid bilayer of the membrane diffuse passively with the help of transport proteins that span the membrane. | 15 | |
| 7680233867 | ion channels | channel proteins that transport ions | 16 | |
| 7680234430 | gated channels | many ion channels function like this, where they open or close in response to a stimulus. For some, the stimulus is electrical. Others open or close when a specific substance other than the one to be transported binds to the channel. | 17 | |
| 7680237812 | sodium-potassium pump | exchanges Na+ for K+ across the plasma membrane of animal cells. ATP's phosphate group binds and unbinds from the transport protein, oscillating the pump between two shapes that have different affinities for Na+ and K+. pumps 3 Na+ out of the cell for every 2 K+ ions it pumps into the cell. | 18 | |
| 7680238588 | charge balance | The cytoplasmic side of the membrane is negative in charge relative to the extracellular side because of an unequal distribution of anions and cations on the two sides. | 19 | |
| 7680239639 | membrane potential | The voltage across a membrane, which ranges from about -50 to -200 millivolts (mV). | 20 | |
| 7680240361 | electrochemical gradient | The combination of two forces acting on an ion: a chemical force (the ion's concentration gradient) and an electrical force (the effect of the membrane potential on the ion's movement.) | 21 | |
| 7680241629 | electrogenic pump | A transport protein that generates voltage across a membrane. (ex. sodium-potassium pump). | 22 | |
| 7680244531 | proton pump | The main electrogenic pump of plants, fungi, and bacteria, which actively transports protons (H+ ions) out of the cell. | 23 | |
| 7680245511 | purpose of electrogenic pumps | By generating voltage across membranes, electrogenic pumps help store energy that can be tapped for cellular work. | 24 | |
| 7680247003 | cotransport | a mechanism where a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes. | 25 | |
| 7680249516 | exocytosis | when a cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane. | 26 | |
| 7680250048 | endocytosis | when a cell takes in biological molecules and particulate matter by forming new vesicles from the plasma membrane. | 27 | |
| 7680250628 | ligand | a term for any molecule that binds specifically to a receptor site on another molecule. | 28 | |
| 7680251658 | phagocytosis | a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membranous sac called a food vacuole. The particle will be digested after the food vacuole fuses with a lysosome containing hydrolytic enzymes. |  | 29 |
| 7680252256 | pinocytosis | the cell "gulps" droplets of extracellular fluids into tiny vesicles. It is not the fluid itself that is needed by the cell, but the molecules dissolved in the droplets. Because any and all included solutes are taken into the cell, pinocytosis is nonspecific in the substances it transports. |  | 30 |
| 7680255423 | receptor-mediated endocytosis | enables the cell to acquire bulk quantities of specific substances, even though those substances may not be very concentrated in the extracellular fluid. Embedded in the membrane are proteins with specific receptor sites exposed to the extracellular fluid, to which specific substances (ligands) bind. The receptor proteins then cluster in regions of the membrane called coated pits, which are lined on their cytoplasmic side b a fuzzy layer of coat proteins. Next, each coated pit forms a vesicle containing the ligand molecules. Note that there are relatively more bound molecules inside the vesicle, but other molecules are also present. After the ingested material is liberated from the vesicle, the emptied receptors are recycled to the plasma membrane by the same vesicle. |  | 31 |
