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AP Bio Chapter 8
Stack #168902
| Word | Definition |
|---|---|
| amphipathic molecule | has both a hydrophilic region and a hydrophobic region (Phospholipids) |
| selective permeability | membrane allows some substances to cross it more easily than others |
| fluid mosaic model | improved model of cell membrane, membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids |
| integral proteins | trans-membrane proteins with hydrophobic regions(non-polar amino acids) that completely span the hydrophobic interior of the membrane |
| Periphial Proteins | not embedded in the lipid bilayer at all, they are appendages loosely bound to the surface of the membrane often to the exposed parts in integral proteins |
| Transport | -provide hydrophilic channels that are selective for a particular solute- transport protein hydrolyze ATP as energy source for pumping substances across the membrane |
| Enzymatic Activity | -exposed active sites- ordered as a team that carries out sequential steps of a metabolic pathway |
| Signal Transducion | -conformational change in the protein that relays the messege inside the cell |
| Intercellular Joining | membrane proteins of adjacent cells hook together in different types of junctions |
| Cell-cell recognition | some glycoproteins serve as identification tags that are specifically recognized by other cells |
| Attachment to the cytoskeleton and extracellular matrix (ECM) | -elements of the cyto.skel. may be bonded to membrane proteins-proteins that adhere to the ECM can coordinate extracellular and intracellular changes |
| transport proteins | - span membrane- function by having hydrophilic channels that certain molecules pass thru- bind to their passengers and physically move them across the membrane |
| diffuusion | the tendancy for molecules of any substance to spread out into the available space |
| concentration gradient | move from high concentraion to low |
| passive transport | the diffusion of a substance across a biological membrane, cell doesn't have to spend energy to make it happen |
| osmosis | diffusion of water across a selectively permeable membrane (passive transport) |
| hypertonic | solution with a higher concentraion of solutes |
| hypotonic | lower concentraion of solutes |
| isotonic | equal concentration of solutes |
| osmoregulation | control of water balance |
| turgid | cell is very firm, healthy state for most plants (hypotonic) |
| flaccid | cell is limp, plant wilts (isotonic) |
| plasmolysis | lethal, lose water and shrink, plasma membrane pulls away from cell wall(hypertonic) |
| facilitated diffusion | spontaneous passage of molecules and ions bound to specific carrier proteins across a biological membrane down their concentraion gradient |
| gated channels | a stimulus (chemical orelectrical) causes them to open or close |
| active transport | moving against the concentration gradient |
| sodium potassium pump | exchanges sodium for potassium across the plasma membrane of animal cells |
| membrane potential | voltage across a membrane ranges from -50_-200 millivolts |
| electrochemical gradient | combonation of forces acting on an ion |
| electrogenic pump | a transport protein that generates voltage across a memrane |
| proton pump | main electrogenic pump of plants,bacteria, fungi, actively transports hydrogen ions out of the cell |
| contransport | a single ATP powered pump that transports a specific solute can indirectly drive the active transport of several other mechanisms |
| exocytosis | when the cell secretes macromolecules by fusion of vesicles with the plasma membrane |
| endocytosis | the cell takes in macromolecules and particulate matter by formingnew vesciles from the plasma membrane |
| phagocytosis | a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane-enclosed sac large enough to be classified as a vacuole |
| pinocytosis | cell gulps droplets of extracellular fluid in tiny vesciles |
| receptor-mediated endocytosis | proteins embedded in the membrane have specific receptor sites exposed to the extracellular fluid |
| ligands | the extracellular substances that bind to the receptors |
Created by:
stophammertime1290
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