Learn: Cell Membranes and the Fluid Mosaic Model

Welcome!You've already learned about gas exchange surfaces and the mammalian lung, including how gases move across membranes using Fick's Law. Today, we'll build on this by exploring cell membranes and the fluid mosaic model, essential for understanding how substances move in and out of cells.

What is the Fluid Mosaic Model?The fluid mosaic model describes the structure of cell membranes. It shows that membranes are made of a phospholipid bilayer with proteins scattered throughout, like tiles in a mosaic. This structure is flexible (fluid) and allows the movement of substances needed for cell function.

Phospholipid BilayerThe cell membrane is made of a double layer of phospholipids. Each phospholipid has a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail. This arrangement forms a barrier that only allows certain molecules to pass through.

Proteins in the MembraneProteins are embedded in the phospholipid bilayer and have various functions. Some act as channels to transport molecules, while others serve as receptors for signals. This is why the cell membrane is described as a mosaic of components.

How Substances Cross the MembraneCell membranes control what enters and exits the cell. Substances cross the membrane using diffusion, osmosis, or active transport. Diffusion relies on concentration gradients, while active transport requires energy from ATP.

Review Time!Great work! You've learned about the fluid mosaic model, phospholipids, proteins, and how substances cross the membrane. Let's test your understanding of these concepts.

Final Review!Well done! You've covered all key concepts related to cell membranes. Here's a final test of your knowledge.