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Questions and Answers
What occurs in the sodium-potassium pump when a phosphate group is detached from ATP?
Which of the following is a key distinguishing feature of plant cells compared to animal cells?
What is the primary consequence of placing plant cells in a hypertonic solution?
Which mechanism is specifically involved in the transport of water across cell membranes?
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According to the fluid mosaic model, what primarily contributes to the dynamic structure of the cell membrane?
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What is the primary function of ATP in the cell?
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How do high salt concentrations affect plant cells?
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In the fluid mosaic model, what does the term 'fluid' refer to?
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What adaptation helps organisms in cold climates maintain plasma membrane fluidity?
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What distinguishes rough ER from smooth ER?
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What role do aquaporins play in cells?
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Which type of molecules can easily pass through the plasma membrane without transport proteins?
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In a U-tube with different solute concentrations, what will happen to the water levels?
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Study Notes
Water Movement in Solutions
- Water moves from areas of lower solute concentration to areas of higher solute concentration (osmosis).
- An example is an U-tube with a semipermeable membrane separating a solution of 0.2 M glucose from a solution of 0.6 M KCl.
- Water will move from the left side (0.2 M) to the right side (0.6 M).
ATP Synthesis
- Adenosine Triphosphate (ATP) is synthesized in the mitochondria of cells.
Impact of High Salt
- High salt concentrations in the soil create a hypertonic solution.
- This causes plant cells to lose water, leading to plasmolysis.
AQP1 Gene
- The AQP1 gene codes for aquaporins.
- Aquaporins facilitate water transport across the membrane.
- A mutation could reduce water uptake, but cells can still take up water through osmosis (although slower without aquaporins).
Plasma Membrane Permeability
- The plasma membrane allows selective permeability.
- Small nonpolar molecules (e.g., oxygen) can pass easily through without transport proteins.
Fluid Mosaic Model
- The “fluid” aspect of the fluid mosaic model refers to lipids and proteins moving laterally within the membrane.
- Lipids and proteins are held together by weak hydrophobic interactions.
Cell Membrane Adaptations
- Organisms in cold climates have cell membranes with more unsaturated fatty acids to maintain fluidity and prevent tight packing at low temperatures.
Surface Area to Volume Ratio
- Cells with a higher surface area to volume ratio are more efficient in exchanging materials.
- Surface area and volume ratio are important considerations for material exchange.
Protein Structure in Membranes
- Proteins embedded in the membrane have regions that interact differently with the membrane interior and aqueous environment.
- Region 1 (hydrophilic) interacts with the membrane interior.
- Region 2 (hydrophobic) interacts with the aqueous environment.
Smooth vs Rough ER
- The rough endoplasmic reticulum (ER) synthesizes and packages proteins for export.
- The smooth ER cannot synthesize and package proteins.
Sodium-Potassium Pump
- The detachment of a phosphate group from ATP induces a conformational change in the sodium-potassium pump.
- This conformational change allows the pump to return to its original position.
Distinguishing Features of Plant Cells
- A central vacuole is a distinguishing feature of plant cells compared to animal cells.
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Description
Explore the principles of water movement in solutions, ATP synthesis, and the effects of salt on plant cells. This quiz covers osmosis, aquaporins, and the selective permeability of plasma membranes. Test your understanding of these vital biological concepts.
