Final answer:
Integral proteins, which span the bilayer, have hydrophobic regions that interact with the bilayer's core and hydrophilic regions for aqueous interactions, while peripheral proteins are bound to the membrane surface by electrostatic forces and hydrogen bonding.
Step-by-step explanation:
The structural feature of a protein molecule that determines its position within the lipid bilayer is primarily related to the distribution of amino acids in the protein. Integral proteins span the hydrophobic interior of the bilayer, interacting with the lipid bilayer via their hydrophobic regions.
Meanwhile, the hydrophilic regions of these proteins are exposed to the aqueous solutions on either side of the membrane. In contrast, peripheral proteins are associated with the surface of the lipid bilayer and are usually bound by hydrogen bonding and electrostatic forces.
Integral proteins have hydrophobic amino acids within their transmembrane regions, allowing them to interact seamlessly with the hydrophobic core of the lipid bilayer. These proteins may also have hydrophilic regions that protrude from the membrane to interact with the extracellular fluid and cytoplasm.
In comparison, peripheral proteins have amino acids that enable them to bind to the hydrophilic heads of phospholipids or to other proteins without penetrating the hydrophobic core.