Question

station 5: fluid mosaic model questions

1. what is the fluid mosaic model?
2. what is the effect of temperature on membranes fluidity at low temperatures?
3. what is the effect of temperature on membrane fluidity at high temperatures?
4. how do unsaturated phospholipids affect membrane fluidity?
5. what role does cholesterol play in maintaining membrane fluidity at high and low temperatures?

station 6: concentration gradients and transport
molecules move across the membrane following a concentration gradient, from areas of high to low concentration, unless energy is used to move them against the gradient. the goal is cellular equilibrium.

1. what is a solute?
2. what is a solvent?
3. what is a concentration gradient?
4. molecules following a concentration gradient will always move from __ to __ concentration.
5. which figure below shows solutes moving with a concentration gradient? (figure a or figure b)

figure b. because its showing that its going down along the gradient

Explanation:

1. The fluid - mosaic model describes the cell membrane as a fluid structure with a 'mosaic' of various proteins embedded in a phospholipid bilayer.
2. At low temperatures, membrane fluidity decreases as the phospholipid tails move less.
3. At high temperatures, membrane fluidity increases as the phospholipid tails move more freely.
4. Unsaturated phospholipids have kinks in their tails which prevent them from packing tightly, increasing membrane fluidity.
5. Cholesterol acts as a buffer: at high temperatures, it restricts movement of phospholipids to reduce fluidity; at low temperatures, it prevents phospholipids from packing too tightly, maintaining fluidity.
6. A solute is a substance dissolved in a solvent to form a solution.
7. A solvent is a substance that dissolves a solute to form a solution.
8. A concentration gradient is the difference in the concentration of a substance across a space.
9. Molecules following a concentration gradient will always move from high to low concentration.

Answer:

1. The cell membrane is described as a fluid structure with proteins embedded in a phospholipid bilayer.
2. Membrane fluidity decreases.
3. Membrane fluidity increases.
4. Increase membrane fluidity.
5. At high temperatures, restricts movement to reduce fluidity; at low temperatures, prevents tight - packing to maintain fluidity.
6. A substance dissolved in a solvent to form a solution.
7. A substance that dissolves a solute to form a solution.
8. The difference in the concentration of a substance across a space.
9. High; low.