Final answer:
Integral proteins and peripheral proteins are embedded in the cell membrane, playing various roles such as transportation, enzymatic activity, and cellular recognition. Integral proteins span the membrane, and peripheral proteins attach to the membrane's surfaces or to integral proteins.
Step-by-step explanation:
Structure of Cell Membranes
Membranes are fundamental cellular structures, and they include two types of proteins: integral proteins and peripheral proteins. Integral proteins are embedded within the plasma membrane and can span the entire membrane. These proteins often function as channels or pumps, facilitating the transport of materials in and out of the cell. On the other hand, peripheral proteins are located on the membrane's exterior or interior surfaces. They can be attached to integral proteins or to the phospholipid molecules of the membrane itself. Peripheral proteins often serve various roles, including acting as enzymes, providing structural support for the cytoskeleton, or forming part of the cell's recognition sites.
In addition, integral proteins frequently have glycoprotein components that face outward from the cell. These contribute to forming the glycocalyx, which is involved in cell recognition and in attracting water to the cell surface.
The physical attachment of peripheral proteins to the cell membrane involves hydrogen bonding and electrostatic forces. This loose association allows them to perform specific functions for the cell, such as facilitating digestion in intestinal cells or regulating the concentration of substances inside the cell.