BIOL 100 Lecture Notes - Lecture 6: Tonicity, Osmoregulation, Osmosis

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copperfish313

4 Jan 2017

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Membranes are fluid mosaics of lipids and proteins. Selectively permeable: allows some substances to cross more easily than others. Molecules move across membrane down its concentration gradient. Move from high concentration to low concentration. Movement from o2 (from outside to inside) to co2 (from inside of cell to outside) - breathing: osmosis. Diffusion of water across a selectively permeable membrane down its concentration gradient. Water always has substances dissolved in it. Tonicity: ability of solution causing cells to gain or lose water. Depends on concentration of solutes in the solution relative: types of solution affecting tonicity. Hypotonic: solute concentration lower than cell water inside cell. Hypertonic: solute concentration higher than cell water outside cell: osmoregulation. Plants and animals prevent too much fluctuation of water for survival. Slightly different between plants and animals: facilitated diffusion. Requires proteins to transport charged/polar molecules across cell. Energy is needed for active transport of solutes.

Related Questions

Read the following scenarios and indicate which of the following processes they describe.

11. Sodium molecules move randomly around a solution of sodium chloride in water, frequently colliding with other sodium ions and chloride ions. secondary active transport diffusion osmosis facilitated diffusion primary active transport

12. Sodium ions (Na+) move through sodium channels in a synthetic membrane. primary active transport secondary active transport facilitated diffusion osmosis

13. Water molecules move into the cytosol of a cell placed in a hypotonic solution. primary active transport secondary active transport facilitated diffusion osmosis

14. Water molecules move into the cytosol of a cell placed in pure water. facilitated diffusion osmosis secondary active transport primary active transport

15. Water molecules move out of a cell placed in a hypertonic solution. facilitated diffusion primary active transport secondary active transport osmosis

16. The action of sodium-potassium pumps moves sodium ions (Na+) out of a cell and potassium ions (K+) into a cell. facilitated diffusion secondary active transport osmosis primary active transport

17. Glucose molecules move into cells lining the intestine against their concentration gradient driven by the movement of sodium ions (Na+) into the cells down their concentration gradient. osmosis secondary active transport primary active transport facilitated diffusion

18. A beaker of water is separated by a selectively permeable membrane that allows the passage of water but not ions. A solution of 4% sodium chloride (NaCl) is placed on one side of the membrane and pure water is placed on the other side of the membrane. The solutions are allowed to equilibrate. At this point, which process is going on? facilitated diffusion osmosis secondary active transport primary active transport

amaranthelk944

1. predict the direction of water movement based on differences in solute concentrations. Use the terms osmotic pressure, hypotonic, isotonic, and hypertonic
2. Why do membranes have to be selectively permeable?

3. What determines whether a particular substance can diffuse (simple or facilitated) through a membrane?

4. What mechanisms drive molecules across membranes? Use the terms concentration gradient, (facilitated) diffusion and active transport.
5. Which parts of the plasma membrane proteins do you expect to be hydrophobic or hydrophilic? Justify your answer.
concise and short answers pls

11. Synthesis of ATP using the energy released as a proton diffuses down a concentration gradient involves the conversion of concentration gradient energy into chemical energyâTrue or false?

12. In the absence of active transport of a molecule, a simple or facilitated diffusion of the molecule will result in an equilibrium of the molecule across the membraneâTrue or false?

13. In the absence of an active transport of a molecule, a simple or facilitated diffusion of the molecule across a membrane will result in zero energy available to do workâTrue or false?

14. If biological membranes were permeable to all solutes osmosis could not occur because the concentration of water will be same on both sides of the membraneâTrue or false?

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BIOL 100 Lecture Notes - Lecture 6: Tonicity, Osmoregulation, Osmosis

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