Lesson 13: Membrane Structure Key Terms

membrane protein

amphiphilic protein of diverse structure and function that associates with the lipid bilayer of cell membranes

amphiphilic

having both hydrophobic and hydrophilic regions, as in a phospholipid or a detergent molecule

glycolipid

lipid molecule with a sugar residue or oligosaccharide attached

cholesterol

an abundant lipid molecule with a characteristic four-ring steroid structure

glycoprotein

any protein with one or more sugars or oligosaccharide chains covalently linked to amino acid side chains

lipid bilayer

thin double sheet of phospholipid molecules that forms the core structure of all cell membranes. The two layers of lipid molecules are packed with their hydrophobic tails pointing inward and their hydrophilic heads outward, exposed to water

transmembrane (TM) protein

a protein that spans across the entire plasma membrane, with part of the protein on one side of the membrane and another part on the other side

phosphoglyceride

a major class of phospholipids that form the main structural foundation of biological cell membranes

plasma membrane

membrane that surrounds a living cell

apical

referring to the tip of a cell, a structure, or an organ. The exposed free surface, opposite to the basal surface

basal

situated near the base. Opposite the apical surface

lateral

the sides that are in contact with neighboring cells

membrane-associated protein

membrane protein not extending into the hydrophobic interior of the lipid bilayer but bound to either face of the membrane by noncovalent interactions with other membrane proteins

single-pass TM protein

membrane protein in which the polypeptide chain crosses the lipid bilayer only once