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| 10703369661 | Plasma membrane | The boundary that separates the living cell from its surroundings | 0 | |
| 10703369662 | Selective permeability | The quality of the plasma membrane that allows some substances to cross it more easily than others | 1 | |
| 10703369663 | Phospholipids | The most abundant lipid in the plasma membrane. Contain hydrophobic and hydrophilic regions. | 2 | |
| 10703369664 | Amphipathic molecules | Contain hydrophobic and hydrophilic regions | 3 | |
| 10703369665 | Fluid mosaic model | States that a membrane is a fluid structure with a "mosaic" of various proteins embedded in it | 4 | |
| 10703369666 | Membrane material | Proteins and lipids | 5 | |
| 10703369667 | Davison and Danielli's sandwich model | A model that suggested that the phospholipid bilayer lays between two layers of globular proteins. This was later proven to be untrue. | 6 | |
| 10704829389 | Why the sandwich model was false | If the proteins were layered on top of the phospholipid bilayer, then hydrophobic parts would be in an aqueous solution | 7 | |
| 10704829390 | Singer and Nicolson's fluid mosaic model | A model that suggests that the membrane is a mosaic of proteins dispersed within the bilayer with only the hydrophilic regions exposed to water | 8 | |
| 10704829391 | Freeze fracture technique | A specialized preparation technique that splits a membrane along the middle of the phospholipid bilayer. These studies of the plasma membrane supported the fluid mosaic model | 9 | |
| 10704829392 | Rapid movement | The way phospholipids in the plasma membrane move | 10 | |
| 10704829393 | Laterally | The way lipids and some proteins drift | 11 | |
| 10704829394 | Transverse flipping | Molecules rarely switch from one phospholipid to the other. The hydrophilic part would have to cross the hydrophobic part to do so, | 12 | |
| 10704829395 | Integral protein | Penetrates the interior of the lipid bilayer. Hydrophilic part extends to aqueous solution on the top and bottom of the bilayer | 13 | |
| 10704829396 | Peripheral protein | Not imbedded in the lipid bilayer. Appendages loosely bound to surface of the membrane. | 14 | |
| 10707554102 | Hydrophobic interactions | The main way membranes are held together | 15 | |
| 10704829397 | Cool temperatures | When membranes switch from a fluid to a solid state | 16 | |
| 10704829398 | Temperature at which a membrane solidifies | Depends on the types of lipids | 17 | |
| 10704829399 | More fluid | Membranes rich in unsaturated fatty acids | 18 | |
| 10704829400 | Less fluid | Membranes rich in saturated fatty acids | 19 | |
| 10704829401 | Fluid | Membranes must be this to work properly | 20 | |
| 10704829402 | Cholesterol | A steroid that has different effects on membrane fluidity at different temperatures | 21 | |
| 10704829403 | Cholesterol at warm temperatures | (37ºC) restrains movement of phospholipids | 22 | |
| 10704829404 | Cholesterol at cool temperatures | Maintains fluidity by preventing tight packing | 23 | |
| 10704829405 | Variations in lipid composition of cell membranes | Appear to be adaptations to specific environmental conditions | 24 | |
| 10704829406 | Ability to change the lipid compositions in response to temperature | Evolved in organisms that live where temperatures vary | 25 | |
| 10704829407 | Transmembrane proteins | Integral proteins that span the membrane | 26 | |
| 10704829408 | Hydrophobic regions of an integral protein | Consist of one or more stretches of nonpolar amino acids often coiled into alpha helices | 27 | |
| 10705294799 | Six major functions of membrane proteins | Transport Enzymatic activity Signal transduction Cell-cell recognition Intercellular joining Attachment to the cytoskeleton and extracellular matrix (ECM) | 28 | |
| 10705294800 | Transport | A protein that spans the membrane may provide a hydrophilic channel across the membrane that is selective for a particular solute. Another protein shuttles a substance from one side to the other by changing shape. Some of these proteins hydrolyze ATP as an energy source to actively pump substances across the membrane. |  | 29 |
| 10705294801 | Enzymatic activity | A protein built into the membrane may be an enzyme with its active site exposed to substances in the adjacent solution. |  | 30 |
| 10705294802 | Signal transduction | A membrane protein (receptor) may have a binding stir 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. |  | 31 |
| 10705294803 | Cell-cell recognition | Some glycoproteins serve as identification tags that are specifically recognized by membrane proteins of other cells. |  | 32 |
| 10705457049 | Intercellular joining | Membrane proteins of adjacent cells may hook together in various kinds of junctions |  | 33 |
| 10705457050 | Attachment to the cytoskeleton and ECM | Microfilaments or other elements of the cytoskeleton may be noncovalently bond to membrane proteins, a function that helps maintain cell shape and stabilizes the location of certain membrane proteins. Can coordinate changes. |  | 34 |
| 10705457051 | How cell recognize one another | By binding to surface molecules, often containing carbohydrates, on the extracellular surface of the plasma membrane | 35 | |
| 10705580454 | Glycolipids or glycoproteins | Membrane carbohydrates may be covalently bonded to to form these | 36 | |
| 10705580455 | Glycolipids | When membrane carbohydrates covalently bond to lipids | 37 | |
| 10705580456 | Glycoproteins | When membrane carbohydrates covalently bond to proteins | 38 | |
| 10705580457 | Vary | Carbohydrate receptors may _____ from individual to individual and species to species | 39 | |
| 10719643097 | Small, hydrophobic (nonpolar) molecules | Can dissolve in the lipid bilayer and pass through the membrane rapidly. Example: hydrocarbons | 40 | |
| 10719643098 | Polar molecules | Do not cross the membrane easily. Example: sugars | 41 | |
| 10719643099 | Transport proteins | Allow passage of hydrophilic substances across the membrane | 42 | |
| 10719643100 | Channel proteins | A type of transport protein that has a hydrophilic channel that certain molecules or ions can use as a tunnel | 43 | |
| 10719643101 | Aquaporins | A type of channel protein that facilitates the passage of water | 44 | |
| 10719643102 | Carrier proteins | A type of transport protein that binds to molecules and changes shape to scuttle them across the membrane. Can use facilitated or active diffusion. Specific for the substance it moves. | 45 | |
| 10720812983 | Diffusion | The tendency for molecules to spread out evenly into the available space | 46 | |
| 10720812984 | Dynamic equilibrium | At this point, as many molecules cross the membrane in one direction as in the other | 47 | |
| 10720812985 | Concentration gradient | The region along which the density of a chemical substance increases or decreases. Substances diffuse down this. | 48 | |
| 10720812986 | No work | The amount of work needed to be done to move a substance down the concentration gradient | 49 | |
| 10720812987 | Passive transport | The diffusion of a substance across a biological membrane in which no energy is expended by the cell to make it happen. | 50 | |
| 10720812988 | Osmosis | The diffusion of water across a selectively permeable membrane | 51 | |
| 10720812989 | Lower solute concentration | Water diffuses across a membrane *from* this region of solute concentration in osmosis | 52 | |
| 10720812990 | High solute concentration | Water diffuses across a membrane *to* this region of solute concentration in osmosis | 53 | |
| 10720812991 | Tonicity | The ability of a surrounding solution to cause a cell to gain or lose water | 54 | |
| 10720812992 | Isotonic solution | Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane |  | 55 |
| 10720822822 | Hypertonic solution | Solute concentration is greater outside the cell than inside the cell; cell loses water |  | 56 |
| 10720833601 | Hypotonic solution | Solute concentration is higher inside the cell than outside the cell; cell gains water |  | 57 |
| 10721010462 | Hypertonic/hypotonic | Environments that create osmotic problems for organisms | 58 | |
| 10721010463 | Osmoregulation | Control of solute concentrations and water balance. A necessary adaptation for life in hypertonic/hypotonic environments. | 59 | |
| 10721010464 | Water balance | Maintained by cell walls | 60 | |
| 10721010465 | Plant cell in a hypotonic solution | Swells until the wall opposes uptake; the cell is firm | 61 | |
| 10721010466 | Turgid | Firm. A plant cell is like this in a hypotonic solution. | 62 | |
| 10721010467 | Plant cell in an isotonic solution | There is no net movement of water into the cell; the cell is limp | 63 | |
| 10721010468 | Flaccid | Limp. A plant cell is like this in an isotonic solution. | 64 | |
| 10721010469 | Plant cell in a hypertonic solution | Plant cell loses water; the membrane pulls away from the wall | 65 | |
| 10721010470 | Plasmolysis | The lethal effect of a plant cell being in a hypertonic solution. The membrane pulls away from the wall. | 66 | |
| 10721010471 | Facilitated diffusion | Transport proteins speed the passive movement of molecules across the plasma membrane. No ATP is required. | 67 | |
| 10721010472 | Ion channels | A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient. | 68 | |
| 10721010473 | Gated channels | A transmembrane protein channel that opens or closes in response to a particular stimulus. Example: ion channel | 69 | |
| 10721010474 | Active transport | The movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy (usually in the form of ATP). | 70 | |
| 10721010475 | What active transport allows cell to do | Maintain concentration gradients that differ from their surroundings | 71 | |
| 10721010476 | Sodium-potassium pump | A transport protein in the plasma membrane of animal cells that actively transports sodium (3) out of the cell, which is high in sodium and slightly positive, and potassium (2) into the cell, which is high in potassium and slightly negative. | 72 | |
| 10731915800 | Membrane potential | The voltage difference across a membrane. Electrical potential between inside and outside of the cell. At rest. | 73 | |
| 10731989848 | How voltage is created | Differences in the positive and negative ions across a membrane | 74 | |
| 10731989849 | -70mV | Resting membrane potential | 75 | |
| 10731989850 | -55mV | Threshold for action potential | 76 | |
| 10731989851 | Electrochemical gradient | Two combined forces that drive the diffusion of ions across a membrane | 77 | |
| 10731989852 | Chemical force | The ion's concentration gradient | 78 | |
| 10731989853 | Electrical force | The effect of the membrane potential on the ion's movement | 79 | |
| 10731989854 | Electrogenic pump | A transport protein that generates voltage across a membrane. The sodium-potassium pump is the major one in animal cells. | 80 | |
| 10732005239 | Proton pump | The main electrogenic pump of plants, fungi, and bacteria |  | 81 |
| 10732005240 | What electrogenic pumps help do | Store energy that can be used for cellular work | 82 | |
| 10732028223 | Cotransport | Occurs when active transport of a solute indirectly drives transport of other substances |  | 83 |
| 10732038165 | Cotransport in plants | Plants commonly use the gradient of hydrogen ions generated by proton pumps to drive active transport of nutrients into the cell | 84 | |
| 10732181745 | How small molecules and water enter/leave the cell | Through the lipid bilayer or via transport proteins | 85 | |
| 10732181746 | How large molecules enter/leave the cell | Cross the membrane in bulk via vesicles | 86 | |
| 10732181747 | Bulk transport | Exocytosis and endocytosis. Requires energy. | 87 | |
| 10732181748 | Exocytosis | Transport vesicles migrate to the membrane, fuse with it, and release their contents. | 88 | |
| 10732181749 | Secretory cells | Use exocytosis to export their products | 89 | |
| 10732188377 | Endocytosis | The cell takes in macromolecules by forming vesicles from the plasma membrane. A reversal of exocytosis. Uses different proteins. | 90 | |
| 10732221728 | Phagocytosis | "Cellular eating." A cell engulfs a particle in a vacuole. The vacuole fuses with a lysosome to digest the particle. | 91 | |
| 10732221729 | Pinocytosis | "Cellular drinking." Molecules are taken up when extracellular fluid is "gulped" into tiny vesicles. | 92 | |
| 10732221730 | Receptor-mediated endocytosis | Binding of ligands to receptors triggers vesicle formation | 93 | |
| 10732221731 | Ligand | Any molecule that binds specifically to a receptor site of another molecule | 94 |
