Question

1) Answer the following questions according to the Two-Dimensional Fluid Model of Membranes:

a) Would a transmembrane protein diffuse slower or faster than a lipid molecule? Why?

b) Lipid molecules change between the bilayer leaflets very slowly. What about transmembrane proteins? How fast can they change across bilayer leaflets?

c) If membrane proteins could change across bilayer leaflets easily, how would the function of the transmembrane protein Na+/K+/ATPase be affected? What will happen to the resting membrane potential?

Answer 1

1(a). Transmembrane protein diffuse slower than a lipid molecule because according to fluid- model of membranes, membranes are made up of phospholipid molecules which are hydrophilic in nature. It opposes the charged particles to cross the membrane.

(b). Lipid molecules change between the bilayer leaflets slowly while transmembrane protein easily.

(c). Na+/ K+/ ATPase flip 3 Na+ outside the cell and 2 K+ inside the cell against the concentration gradient using ATP. This transmembrane protein change easily.

It's stabilizes the resting membrane potential after depolymerization.