Learn: Membranes and Transport Mechanisms

Welcome!Today we'll explore membranes and how substances move across them. These processes are vital for cell function and survival.

What is the Cell Membrane?The cell membrane is a thin, flexible barrier that surrounds the cell. It controls the movement of substances into and out of the cell and maintains the internal environment.

Structure of the MembraneThe cell membrane is made up of a phospholipid bilayer, which consists of two layers of phospholipids. Proteins, cholesterol, and carbohydrates are embedded within it to help with specific functions like transport and cell recognition.

Transport MechanismsSubstances move across membranes by diffusion, osmosis, and active transport. Each process suits different needs depending on the molecule and the energy available.

DiffusionDiffusion is the movement of particles from a region of high concentration to a region of low concentration. It happens naturally and doesn’t require energy.

OsmosisOsmosis is the diffusion of water across a semi-permeable membrane, from a region of high water potential to low water potential. It’s essential for maintaining cell turgidity.

Active TransportActive transport moves substances against their concentration gradient (low to high) using energy from the cell. Carrier proteins are involved in this process.

Facilitated DiffusionFacilitated diffusion is a type of passive transport that uses carrier or channel proteins to help large or charged molecules cross the membrane.

Review Time!Great work! You've learned about membranes and transport mechanisms. Now let’s test your understanding with a few final questions.