Main content of bilayer cell membrane is: March 2009

Ans. B: CholesterolBiological membranes typically include several types of lipids other than phospholipids. A paicularly impoant example in animal cells is cholesterol, which helps strengthen the bilayer and decrease its permeability.Cholesterol also helps regulate the activity of ceain integral membrane proteins. Integral membrane proteins function when incorporated into a lipid bilayer.Because bilayers define the boundaries of the cell and its compaments, these membrane proteins are involved in many intra- and inter-cellular signaling processes.