What is the purpose of the high concentration of hydrogen ions created by the Electron Transport System on one side of the cell membrane?
The correct answer and explanation is:
The purpose of the high concentration of hydrogen ions (protons) created by the Electron Transport System (ETS) on one side of the membrane is to generate a proton gradient, which is crucial for the production of ATP during cellular respiration. This process takes place in the mitochondria of eukaryotic cells, specifically in the inner mitochondrial membrane.
As electrons pass through the complexes of the ETS (Complexes I, III, and IV), energy is released. This energy is used to pump protons from the mitochondrial matrix into the intermembrane space, creating a high concentration of hydrogen ions on the outer side of the inner mitochondrial membrane. This results in a proton gradient, also known as the electrochemical gradient, where the concentration of protons is much higher in the intermembrane space than in the matrix.
The high concentration of hydrogen ions in the intermembrane space generates both a concentration gradient and an electrical gradient across the membrane. These gradients create potential energy, often referred to as the proton motive force (PMF). This force drives protons back into the mitochondrial matrix through ATP synthase, a protein complex embedded in the membrane.
As protons flow through ATP synthase, their movement causes the enzyme to catalyze the phosphorylation of ADP into ATP. This process, known as oxidative phosphorylation, is the final stage of cellular respiration and is responsible for producing the majority of the ATP required by cells for energy.
In summary, the purpose of the proton gradient created by the ETS is to store energy in the form of a gradient, which is later used to drive ATP synthesis, the primary energy source for the cell.