The surface properties of biomembranes play a crucial role in the uptake and transport of molecules across the membrane. These properties include surface tension, hydrophobicity, and surface charge, which collectively determine the selective permeability of the membrane and the efficiency of transport mechanisms.1. Surface tension: Surface tension arises from the cohesive forces between molecules at the surface of the membrane. In the case of biomembranes, the lipid bilayer structure creates a barrier that prevents the free movement of polar and charged molecules across the membrane. This selective permeability allows the cell to maintain a stable internal environment by regulating the transport of ions and molecules. For example, aquaporins are specialized channels that facilitate the transport of water molecules across the membrane while excluding ions and other solutes.2. Hydrophobicity: The lipid bilayer of biomembranes consists of hydrophobic tails and hydrophilic heads. This amphipathic nature creates a hydrophobic core that acts as a barrier for polar and charged molecules, while allowing the passive diffusion of small, nonpolar molecules such as oxygen and carbon dioxide. The hydrophobic effect also influences the folding and insertion of membrane proteins, which contain both hydrophobic and hydrophilic regions. For example, the glucose transporter GLUT is a membrane protein that facilitates the transport of glucose across the membrane. Its hydrophobic regions interact with the lipid bilayer, while its hydrophilic regions form a channel for glucose to pass through.3. Surface charge: The surface charge of biomembranes is determined by the presence of charged molecules, such as phospholipids, glycolipids, and membrane proteins. The overall charge of the membrane can influence the transport of charged molecules and ions across the membrane. For example, the sodium-potassium pump Na+/K+-ATPase is a membrane protein that uses ATP to transport sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient necessary for various cellular processes. The surface charge of the membrane can also affect the binding and interaction of charged molecules, such as hormones and neurotransmitters, with their respective membrane receptors.In summary, the surface properties of biomembranes, including surface tension, hydrophobicity, and surface charge, play a critical role in determining the selective permeability of the membrane and the efficiency of transport mechanisms. These properties allow cells to maintain a stable internal environment and facilitate the exchange of molecules and ions necessary for cellular function.