Final answer:
Peripheral proteins attach loosely to the cell membrane and can be associated with ion channels or transmembrane receptors. They do not span the entire membrane but are important for cell functions like signaling, attaching to the cytoskeleton, and cell recognition.
Step-by-step explanation:
Peripheral Proteins in Cell Membranes
Proteins that attach loosely to the plasma membrane are known as peripheral proteins. These proteins do not span the entire membrane but are vital for various cellular functions, such as signaling and acting as enzymes. Peripheral proteins can attach to the membrane by binding either to other membrane proteins or to the polar regions of phospholipids. Unlike integral proteins that are embedded within the membrane, peripheral proteins are located on the outer or inner surfaces. They may serve as structural attachments for the cytoskeleton, participate in cell recognition, or anchor themselves to one side of the membrane.