Plasma membrane

The following session will cover plasma membrane within the context of this subject focusing on the structure and composition of the plasma membrane emphasizing its fluid mosaic model and selective permeability. We will discuss the diverse roles of membrane proteins, including transport, signaling, and maintaining cell integrity. Key mechanisms of molecule transport both passive and active will be explained in relation to cellular survival. Finally, we will explore how the plasma membrane facilitates environmental sensing, communication, and cell recognition. The plasma membrane is an essential boundary that separates the cell's internal environment from its surroundings. More than a simple barrier, it's a dynamic interface vital for communication and homeostasis. Structurally, it's a phospholipid bilayer. Each molecule has a hydrophilic head facing water and hydrophobic tails inward. Interspersed proteins play structural and functional roles while cholesterol modulates fluidity. Carbohydrate chains aid recognition and signaling. The fluid mosaic model describes this adaptability. A defining feature of the plasma membrane is its selective permeability allowing control over which substances enter or exit the cell. Small uncharged molecules like oxygen and carbon dioxide can move freely through the lipid bilayer as can water via diffusion or aquaporins. Ions, sugars and most polar molecules require transporters or channels.