Question

According to the 'unit membrane model,' the thickness of the cell membrane is about

• A. 200 nm
• B. 7.5 nm
• C. 150 nm
• D. 1.0 nm

Answer 1

Answer: (B)

7.5 nm

Unit membrane model was given by Robertson in 1959. According to this concept, plasma membrane has a trilaminate structure with an electron transparent lipid bilayer 35 $\mathring{A}$ thick lying sandwiched between electron dense protein layers 20 $\mathring{A}$ thick each. Thus, the total thickness of membrane will be 75 $\mathring{A}$ or 7.5 nm.

So, the correct answer is '7.5 nm'