A-Level Biology - Fluid Mosaic Model - What Cell Membranes Are | Key Structures (2027/28 exams)

Introduction to Cell Membranes00:00:07

Cell membranes act as barriers separating the inside of a cell or organelle from the outside. They are composed of a phospholipid bilayer, making them selectively permeable to regulate substance movement.

Fluid Mosaic Model Overview00:01:47

The fluid mosaic model describes the membrane's structure: 'fluid' refers to the movement of phospholipids, and 'mosaic' refers to the various proteins embedded throughout the bilayer.

Phospholipid Bilayer and Cholesterol00:02:41

Phospholipids form a bilayer with hydrophilic heads and hydrophobic tails, creating a core that blocks water-soluble substances. Cholesterol molecules sit within this bilayer, helping to stabilize membrane fluidity across varying temperatures.

Membrane Proteins00:04:27

Proteins are categorized as intrinsic (integral), which span the bilayer for transport, or extrinsic (peripheral), which remain on one side for signaling and structural support.

Glycoproteins and Glycolipids00:05:19

Glycoproteins and glycolipids are molecules with attached carbohydrates that play essential roles in cell adhesion, recognition, and cell signaling.