Fluid mosaic membranes — common mistakes

When describing membrane fluidity, focus on the movement of phospholipids (lateral diffusion, rotation, flexion) and proteins. Avoid simply saying it's 'not rigid'. For 'mosaic', emphasise the distribution of embedded and surface proteins. Always link the structural features directly to their function and refer to specific components.

The primary function is to regulate the movement of substances into and out of the cell, maintaining homeostasis. It also plays critical roles in cell signalling, adhesion, and recognition. You can deepen your understanding by exploring our free Cambridge Biology 9700 course content and practising with past papers.

At higher temperatures, phospholipids gain kinetic energy, increasing membrane fluidity. At lower temperatures, fluidity decreases, potentially making the membrane too rigid. Cholesterol, found in animal cells, helps buffer these changes, maintaining optimal fluidity. Our premium lessons dive deeper into these effects and provide past paper questions to test your knowledge.

The term 'mosaic' refers to the scattered and irregular arrangement of various proteins embedded within or attached to the phospholipid bilayer, much like tiles in a mosaic artwork. These proteins are not uniformly distributed but form a diverse pattern essential for specific functions. Learn more about membrane proteins and their roles in our free 9700 Biology revision series, complete with detailed explanations and practice questions.