1.2.3 Membranes consist mainly of lipids and proteins with mass ratio ranges between 1: 4 to 4: 1(membranes with different functions have different proteins, some lipids and proteins have covalently linked carbohydrates) 1.2.4 Membranes contain specific proteins (e.g, pumps, channels, receptors, energ. transducers, and enzymes) to mediate their distinctive functions1.2.3 Membranes consist mainly of lipids and proteins with mass ratio ranges between 1:4 to 4:1 (membranes with different functions have different proteins, some lipids and proteins have covalently linked carbohydrates). 1.2.4 Membranes contain specific proteins (e.g., pumps, channels, receptors, energy transducers, and enzymes) to mediate their distinctive functions