This is a worksheet that helps students understand how the molecular structures of the three main components of cell membranes (i.e. phospholipids, cholesterol, and proteins) explains their respective functions. Students should understand that the molecular components of the cell membrane are largely held in place via the hydrogen bonds they form with water on either side of the membrane, not with one another. This is an effective way to help students make connections between concepts in biochemistry (e.g. surface charge, hydrogen bonding, functional groups, hydrophobic/hydrophilic properties, etc.) and the concepts they will learn as they study cell membranes (e.g. membrane transport, osmosis, exocytosis, membrane fluidity, etc.). This can also be used as a formative assessment or summative assessment. The level of detail that students are expected to provide may range from introductory to advanced, depending on the class grade and level.