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BI 212 M1 - Cell 2
BI 212 Midterm 1 - Cell Structure II
| Question | Answer |
|---|---|
| Amphipathic | Lipids are considered this, which means having both a hydrophilic region and a hydrophobic region. |
| Selective Permeability | Membrane that allows some substances to cross more easily than others. Picks and chooses what gets in and out. |
| Fluid Mosaic Model of Membranes | The notion that the membrane is not a rigid structure, but more 'fluid' and has a variety of proteins embedded in it or attached to a double layer. |
| Extracellular Matrix (ECM) | Elaborate configuration on the outside of animal cells whose main ingredients are glyco-proteins secreted by the cells. ECM can regulate cell's behavior, also influence activity of genes in the nucleus. |
| Collagen | The most abundant Glycoprotein in ECM, forms strong fibers outside the cells, embedded in a web of proteoglycans. |
| Proteoglycans | Molecule in ECM that consists of a small core protein with many carb chains. Proteoglycan Complexes are formed when 100's of proteoglycans become nocovalently attached to a single polysaccharide. |
| Fibronectin | A glycoprotein that bind to cell surface receptor proteins (integrens), another way cells are attached to ECM. |
| Integrins | Surface receptor proteins that are built into the plasma membrane, they span the membrane and bind on their cytoplasmic to associated proteins attached to microfilaments. |
| Tight Junctions | Where the plasma membranes of neighboring cells are very tightly pressed against each other and bound by specific proteins. Prevents the leakage of Extracellular fluid across a layer of epithelial cells. |
| Desmosomes | Aka Anchoring Junctions, function like rivets, fastening cells together into strong sheets. Intermediate filaments anchor desmosomes in the cytoplasm. |
| Gap Junctions | AKA Communicating Junctions, provide cytoplasmic channels from one cell to an adjacent cell. They consist of membrane proteins that surround a pore through which ions, sugars, AA's, etc may pass. |
| Integral Membrane Proteins | Proteins that penetrate the hydrophobic core of the lipid bilayer, may have channels that allow the passage of hydrophilic substances. |
| Transmembrane Proteins | Integral Proteins that span both layers of the membrane. |
| Peripheral Proteins | Not embedded in bilayer, rather are appendages loosely bound to the surface of the membrane, often exposed to integral proteins. |
| Diffusion | the result of thermal motion in molecules, it is the movement of molecules of any substance so that they spread out evenly into the available space. Individual molecules move random, but population may be directional. |
| Dynamic Equilibrium | balance of molecules in a solution, achieved by diffusion |
| Passive Transport | Movement from high concentration to low concentration across a biological membrane, uses no energy. For small nonpolar molecules. |
| Facilitated Diffusion | Movement down the concentration gradient (high to low) across a membrane with the help of proteins, channels within proteins (hydrophilic corridor). |
| Active Transport | Diffusion against concentration gradient (low to high), done through the action of proteins, but costs energy. |
| Channel Protein | Provides a corridor through membrane that allows a specific molecule or ion to cross the membrane. One type is gated channel, which open or close in response to a stimulus. |
| Carrier Protein | Undergoes a change in shape that translocates the solute across the membrane during the change. |
| Membrane Potential | All cells have voltages across PM's, it is electrical potential energy. Cytoplasm has - charge relative to extracellular fluid, uneven dist. of anions. This voltage is membrane potential. |
| Electrochemical Gradient | Inside of cell is (-), thus favoring transport of cations into cell and anions out of cell. These two forces drive diffusion (ions concentration gradient, and membrane potential), this is called the Electrochemical gradient. |
| Proton Pump | Actively transports hydrogen ions (H+) out of the cell, transfers positive charge from the cytoplasm to extracellular fluid, important for ATP synthesis during cellular respiration. |
| Co-transport | Energy to move H+ against gradient, movement of H+ down Electrochemical Gradient, Co-transport of another molecule. |
| Osmosis | Diffusion of water across a selectively permeable membrane, to balance water between its cell and the environment. |
| Tonicity | Accounting for both solute concentration and membrane permeability. Water moves from low to high solute concentration. |
| Isotonic to a cell | No net movement of water, equal solute on both sides of membrane. Normal for animal cells, causes plant cells to be flaccid. |
| Hypertonic to a cell | More solute outside the cell, net flow of water out of cell. Animal sells become crenated (shriveled) and plant cells plasmolyzed (PM pulls away from cell wall). |
| Hypotonic to a cell | Less solute outside of cell, net flow of water into cell. Animal cells become Lysed (swell and explode), pland cells become turgid (normal/ideal condition). |
| How does cholesterol affect fluidity of membrane? | Cholesterol lowers the fluidity at moderate temperatures by reducing phospholipid movement (takes up space), also lowers the temperature need to make solids by disrupting the packing of the phospholipids. |
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