C. The lipid bilayers found in cells are fluid, yet asymmetrical in the composition of the monolayers. Is this a paradox? Explain your answer. D. Why do transmembrane domains of proteins typically fold into alpha helices or beta-barrels rather than exist as disordered chains? Solution C) The lipid bilayer is made up amphipathic lipid molecules, that is it contains a polar head (hydrophilic- water loving) and non- polar tails (hydrophobic). The polar heads face the aqueous envoriment and the tails towards the inside. An important property of the lipid bilayer is its fluidity . This property is due to the non-polar tails and is dependent on temperture and the lipid composition. Fludity in the bilayer helps in the movement of the molecules within the structure and in maintianing permeability. The two monolayers are asymmetrical in their structure as well as in function. The asymetrically nature of the layers is based on the different kinds of protiens found in the monolayers and their specific orientation in the membrane. This asymmetric nature helps cells to distinguish between the inner surface of the cell and the outer surface of the cell and plays an important role in the during apoptosis and other numerous cellular functions..