How cells move molecules without spending a drop of energy
In short: Diffusion is a fundamental passive process that allows life to function. This video breaks down how cells transport essential substances across membranes using both simple pathways and specialized protein machinery.
The video explains the mechanics of diffusion, defined as the net movement of particles down a concentration gradient. Because it is a passive process, it requires no cellular energy. It distinguishes between simple diffusion, which allows small, non-polar molecules to pass through membranes freely, and facilitated diffusion.
Facilitated diffusion is necessary for larger or polar molecules, which require specific channel or carrier proteins to cross. The rate of this movement is governed by three primary factors: the steepness of the concentration gradient, the available surface area of the membrane, and the quantity of transport proteins available.
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Sources
- Summary by Intellect · source: A-Level Biology - Diffusion - Simple & Facilitated | Factors Affecting Diffusion (2027/28 exams)
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