AP BIOLOGY

Detailed explanation-1: -Their hydrophilic regions are exposed to water on either side of the membrane. The hydrophobicity of some of these transmembrane proteins is increased by the covalent attachment of a fatty acid chain that inserts into the cytosolic monolayer of the lipid bilayer (example 1 in Figure 10-17).

Detailed explanation-2: -Polar and hydrophilic amino acids are most commonly found in the cytosolic and exoplasmic regions of the membrane, as these regions interact with the aqueous environment outside of the membrane.

Detailed explanation-3: -The hydrophilic regions of the phospholipids tend to form hydrogen bonds with water and other polar molecules on both the exterior and interior of the cell. Thus, the membrane surfaces that face the interior and exterior of the cell are hydrophilic.

Detailed explanation-4: -The heads, which form the outer and inner linings, are “hydrophilic” (water loving) while the tails that face the interior of the cell membrane are “hydrophobic” (water fearing). Water is attracted to the outsides (red) of the membrane but is prevented from going through the non-polar interior (yellow) layer.