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26 Cards in this Set
- Front
- Back
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 |
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Amphipathic |
Having both a hydrophilic region and a hydrophobic region |
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Diffusion |
The random thermal motion of particles of liquids, gasses, or solids. In the presence of a concentration or electrochemical gradient, it results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated |
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Endocytosis |
Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane |
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Exocytosis |
The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane |
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Facilitated diffusion |
The passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins requiring no energy expenditure |
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Fluid mosaic model |
The currently accepted model of a cell membrane structure which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids |
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Hypertonic |
Referring to a solution that when surrounding a cell will cause the cell to lose water |
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Hypotonic |
A solution that when surrounding a cell will cause the cell to take up water |
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Integral protein |
A transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein) |
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Isotonic |
A solution that, when surrounding a cell causes no net movement of water into or out of the cell |
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Ligand |
A molecule that binds specifically to another molecule usually a larger one |
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Ligand-gated ion channel |
A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule allowing or blocking the flow of specific ions. Also called an ionotropic receptor |
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Osmosis |
The diffusion of free water molecules across a selectively permeable membrane |
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Passive transport |
The diffusion of a substance across a biological membrane with no expenditure of energy |
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Peripheral proteins |
Proteins loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer |
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Phagocytosis |
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals |
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Phosphorylation cascade |
A series of chemical reactions during cell signaling mediated by enzymes (kinases) in which each kinase in turn phosphylates and activates another ultimately leading to phosphorylation of many proteins |
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Pinocytosis |
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes |
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Protein kinase |
An enzyme that transfers phosphate groups from ATP to a protein, thus phosphorylating the protein |
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Protein phosphatase |
An enzyme that removes phosphate groups from dephosphorylates proteins often functioning to reverse the effects of of a protein kinase |
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Selective permeability |
A property of biological membranes that allows them to regulate the passage of substances across them |
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Receptor mediated endocytosis |
The movement of specific molecules into a cell by the inward budding of vesicles containing proteins with receptor sites specific to the molecules being taken in. It enables the cell to acquire bulk quantities of specific substances |
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Second messengers |
A small nonprotein water soluble molecule or ion such as a calcium ion or cyclic AMP that relays a signal to a cell's interior in response to a signaling molecule bound by a signal receptor protein |
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Signal transduction pathway |
A series of steps linking a mechanical, chemical, or electrical stimulus to a specific cellular response |
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Tonicity |
The ability of a solution surrounding a cell to cause that cell to gain or lose water |