Question

You are performing an experiment with a new enzyme. This enzyme removes the heads of phospholipids. The enzyme cannot pass through plasma membranes. You have cells that have an outer membrane made up of a phospholipid bilayer, with a layer of phospholipids facing the inside of the cell and the other layer facing the fluid environment outside the cell. What do you predict will happen when you add the enzyme to the fluid containing your cells?

Choose one:

A. Not enough information is given to make a prediction.

B. The heads of the phospholipids in both layers of the membrane (those facing both the inside and outside of the cell) will be removed.

C. Only the heads of the phospholipids facing the inside of the cell will be removed.

D. Only the heads of the phospholipids facing the outside environment will be removed.

Answer 1

Answer: Option B is correct
Explanation:
It is given that a phospholipid bilayer is suspended in a solution.
the bilayer contains hydrophilic heads exposed outwards and the tails are buried inside.

It is given that an enzyme cleaves the exposed head regions.
Once the head regions of the outer layer are cleaved off, the outer lipid layer becomes unstable leading to the eventual conversion of the bilayer into a micelle.
The micelle contains exposed heads which will again be cleaved off by the enzyme. So, the heads of both layers would be cleaved off.