CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon


Question

According to the widely accepted "fluid mosaic model" cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several respects. In this regard, which of the following statements is incorrect?


A
Proteins can also undergo flip-flop movements in the lipid bilayer
loader
B
Many proteins remain embeded within the lipid bilayer
loader
C
Proteins in cell membranes can travel within the lipid bilayer
loader
D
Proteins can remain confined within certain domains of the membranes
loader

Solution

The correct option is D Proteins can also undergo flip-flop movements in the lipid bilayer
Singer and Nicolson gave the Fluid Mosaic Model of the plasma membrane in 1972. According to this model, membranes are quasifluidic in nature compared with proteins floating in a sea of lipids. External proteins are called extrinsic or peripheral whereas internal proteins are named as intrinsic or integral. Membrane proteins may function as enzymes, permeases, carriers, receptors etc. Large integral proteins extending from outside to inside are called Tunnel proteins or transmembrane proteins eg glycoproteins. Singly or in groups they function as channels for passage of water, solutes and ions. Till recently it was believed that proteins can diffuse within the membrane but not across the membrane. The diffusion across the membrane is called flip-flop movement. Recent studies have however confirmed that proteins can diffuse across the entire width of the membrane and show flip-flop movement. However, these movements are rare.
So, the correct answer is 'Proteins can also undergo flip-flop movements in the lipid bilayer'.

Biology

Suggest Corrections
thumbs-up
 
0


similar_icon
Similar questions
View More


similar_icon
People also searched for
View More



footer-image