Question

1. On a piece of paper, draw and label the parts of a typical cell membrane around a cell.

2. In your picture, create a concentration gradient across your cell membrane for glucose (high glucose concentration inside your membrane and low outside your membrane).

3. Draw and describe what process your cell would use to transport glucose into your cell.

4. If your cell membrane was impermeable to glucose, what direction would water flow (into or out of your cell)? Is your cell in a hypertonic, hypotonic or isotonic solution in this scenario?

Answer 1

1. Biological membranes are lipid bilayers.
They contain hydrophilic head groups exposed on the surface and hydrophobic tails buried inside.

2. Concentration gradient = Difference in concentration across the membrane

3. Glucose is a polar molecule. So, it cannot freely cross the membrane. It requires a carrier protein for its transport.
It has to be transported from low concentration to high concentration. Hence ATP hydrolysis is required
= Active transport

4. More glucose concentration in cell = Hypertonic
Less glucose concentration outside = Hypotonic
Water moves from hypotonic region to hypertonic region
i.e. Water moves into the cell = Endosmosis
See the image