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Hydrogen ions concentration gradient

Definition

This refers to the difference in concentration between two areas separated by a membrane. In biological systems, this often involves hydrogen ions (protons) moving across a membrane, such as the inner mitochondrial membrane or thylakoid membrane in chloroplasts.

Analogy

Think of this like a crowd of people (the hydrogen ions) at a concert. If there's an exit on one side of the venue, over time more people will move towards that exit creating a gradient - more people near the exit (high concentration) and fewer people further away (low concentration).

Related terms

Active Transport: The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

Passive Transport: The movement of biochemicals and other atomic or molecular substances across cell membranes without need for energy input.

Osmosis: A process by which molecules of a solvent tend to pass through a semipermeable membrane from less concentrated solution into more concentrated one, thus equalizing concentrations on each side.