The motion of lipid molecules in a synthetic bilayer can be studied by various techniques. Which of the following has been observed in these systems?
A) Phospholipids diffuse rapidly within and between the two leaflets of a bilayer.
B) An average lipid molecule can diffuse the length of about 2 micrometers in a fraction of a millisecond.
C) The flip-flops are very rare for phospholipids but cholesterol molecules flip-flop more often.
D) Within a bilayer, lipid molecules rarely rotate about their long axis, but diffuse laterally at very high rates.
E) All of the above.

Question

Quizplus · Accepted Answer

In contrast to high lateral diffusion and rotation rates, flip-flop rates are very low for phospholipids, although not so low for cholesterol. Due to the high lateral diffusion coefficients, an average lipid molecule can travel the length of a bacterial cell (approximately 2 µm) in about a second.

The Motion of Lipid Molecules in a Synthetic Bilayer Can