Question

EXPLAIN how the PMF is produced and Describe TWO ways it is used to do work.

Answer 1

The paricles tend to diffuse from high concentration to low concentration across the mebranes. The ions across membrane produce electrochemical gradient by moving across the membrane during which the positive ions move down to electric potential from positive to negative side while negative charged ions in opposite direction. These two activities produce electrochemical gradient across membranes and proton motive force (PMF) is derived from it.

Thus, proton motive force is defined as measure of potential energy stored in the form protons (H⁺ ions) and voltage gradients across the membrane. The electrochemical gradient generating proton motive force stores energy for cellular activities and acts similar to a battery. The strored energy of PMF can also be used for cellular movements by energizing flagella. Thus, PMF is pH and charge difference produced across cell membrane resulting in electrochemical potential. PMF is generated during electron transport chain of cellular respiration and energy is produced in the form ATP by using proton pumps. PMF is also generated during photosynthesis in plants.