Singer and Nicolson (1972) suggested the widely accepted fluid mosaic model of biological membranes. According to this model the plasma membrane contains a bimolecular lipid layer, both surfaces of which are interrupted by protein molecules. Some proteins are attached at the polar surface of the lipid (ie, called extrinsic protein) while, other (called intrinsic proteins) either partially penetrate the bilayer or span the membrane entirely to stick out on both sides (called transmembrane proteins). Mobility of membrane proteins due to fluid property of lipid bilayer was demonstrated by classical experiment of D Frye and M Edidin (1970). The movement of lipid molecules from one lipid monolayer to another monolayer is called flip-flop-movement. Flip-flop movement is rarely found in lipid molecules whereas it remain absent in protein molecules.
Keeping in view the 'fluid mosaic model' for the structure of cell membrane, which one of the following statements is correct with respect to the…
NEET UG 2008 — Botany Cell - The Unit of Life
Keeping in view the 'fluid mosaic model' for the structure of cell membrane, which one of the following statements is correct with respect to the movement of lipids and proteins from one lipid monolayer to the other (described as flip-flop movement)?
Held on 30 Apr 2008 · Verified 9 Jul 2026.
Options
- A
Both lipids and proteins can flip-flop
- B
While lipids can rarely flip-flop, proteins cannot
- C
While proteins can flip-flop, lipids cannot
- D
Neither lipids, nor proteins can flip-flop
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