| Term | Definition |
|---|
| selective permeability | the plasma membrane exhibits ________ ________; it allows some substances to cross it more easily than others |
| amphipathic molecule | a phospholipid is an ________ _________; it has both a hydrophilic and a hydrophobic region |
| 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 (what kind of model is this?) |
| freeze fracture | a method of preparing cells for electron microscopy is called _____ ______, which splits a membrane along the middle of the phospholipid bilayer |
| temperature buffer | cholesterol is a _______ _________ for the membrane; it resists changes in membrane fluidity that can be caused by changes in temperature |
| integral proteins | ______ _______ penetrate the hydrophobic core of the lipid bilayer. their hydrophobic regions consist of one or more stretches of nonpolar amino acids, usually alpha helices. |
| peripheral proteins | _______ ________ aren't embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins |
| cell-to-cell recognition | _____-__-____ ________ is a cell's ability to distinguish one type of neieghboring cell from another |
| glycolipids | carbohydrates covalently bonded to lipids |
| glycoproteins | carbohydrates covalently bonded to proteins |
| transport protein | some hydrophilic substances can avoid the lipid bilayer by passing through this |
| carrier proteins | some transport proteins, called _____ ____, function by having a hydrophilic channel that certain molecules or atomic ions can use as a tunnel through the membrane |
| aquaporins | the passage of water molecules through the membrane in certain cells is greatly facilitated by channel proteins called ___________ |
| diffusion | _______ is the tendency for molecules of any substance to spread out evenly into the available space |
| passive transport | the diffuison of a substance across a biological membrane is called _______ _________ because the cell doesn't have to expend energy to make it happen |
| osmosis | the diffusion of water across a selective permeable membrane is called _________ |
| tonicity | ________ is the ability of a solution to cause a cell to gain or lose water |
| isotonic | if a cell without a wall is immersed in an environment that is ______ to the cell, there will be no net movement of water across the plasma membrane (water flows at the same rate in both directions) |
| hypotonic | when a cell is in a solution that is ______ to the cell, water will enter the cell faster than it leaves, and will cause the cell to swell and burst |
| hypertonic | if a cell is in a solution that is _______ to the cell, the cell will lose water to its environment, shrivel, and probably die |
| osmoregulation | _______ is the control of water balance |
| turgid | _____ is a healthy state for most plant cells, where the cell wall exerts pressure to stop further intake of water |
| flaccid | if a plant's cells and their surroundings are isotonic, there is no net tendency for water to enter, and the cells become _______ |
| plasmolysis | when a cell is in a hypertonic environment, the cell will lose water to its surroundings, shrink, and its plasma membrane will pull away from the wall |
| facilitated diffusion | many polar molecules and ions impeded by the lipid bilayer of a membrane diffuse passively with the help of transport proteins that span the membrane |
| ion channels; gated channels | ____ ________ allow certaion ions to pass and they can function as _______ _____, where a stimulus causes them to open or close |
| active transport | to pump a molecule across a membrane agaist its gradient requires work; the cell must expend energy |
| sodium-potassium pump | a ______-_______ _____ exchanges sodium (Na+) for potassium (K+) across the plasma membrane of animal cells |
| voltages | all cells have _______ across their plasma membranes |
| membrane potential | the _______ ________ is an energy source that affects the traffic of all charged substances across the membrane |
| electrogenic pump | a transport protein that generates voltage across a membrane is called a _______ ________ |
| protein pump | the main electrogenic pump in plants, fungi and bacteria is a _______ _________, which actively transports hydrogen ions out of the cell |
| contrasport | a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in a mechanism called _________ |
| endocytosis | the cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane |
| exocytosis | the cell secretes macromolecules by the fusion of vesicles with the plasma membrane |
Combine with other sets
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