Summary
The combined chemical and electrical gradient of protons that powers ATP synthase and transport.
In depth
PMF = Δψ (membrane potential) + ΔpH term. In mitochondria, it is dominated by membrane potential (about -180 mV). It also drives transport (phosphate, ADP/ATP exchange) and bacterial flagella.
PMF has two parts; in chloroplasts the ΔpH dominates. It also drives ADP/ATP exchange.
Key idea: PMF is a store of energy used for several cell processes.
The proton motive force (PMF) is the stored energy of a proton gradient across a membrane. It has two components: the difference in proton concentration (delta pH) and the electrical potential difference (membrane potential). In mitochondria, the matrix is more alkaline and negative, with a potential of about 150 to 180 mV, and the PMF is about 200 mV.
The PMF drives ATP synthesis, but also the import of pyruvate and phosphate, calcium uptake and heat production by uncoupling. In bacteria it drives flagellar rotation and transport (such as lactose permease). In chloroplasts the PMF is mostly delta pH.
Example: protonophores like FCCP collapse the PMF and halt ATP synthesis.
Frequently asked questions
What is Proton Motive Force?
The combined chemical and electrical gradient of protons that powers ATP synthase and transport.
Which area of biology covers Proton Motive Force, and how advanced is it?
Proton Motive Force is one of the 53 topics in Metabolism & Bioenergetics. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Chemiosmosis, Mitochondrial Uncoupling, ATP Synthase Rotary Mechanism.
Why does Proton Motive Force matter?
It is a universal energy currency across life.
Can you give an example of Proton Motive Force?
Bacteria use PMF to spin flagellar motors.
What should I learn before Proton Motive Force?
Work through the Beginner topics in Metabolism & Bioenergetics first, such as Metabolism, Anabolism and Catabolism, ATP, then return to Proton Motive Force. Advanced topics assume the Intermediate vocabulary.
What topics are related to Proton Motive Force?
The closest topics to Proton Motive Force are Chemiosmosis, Mitochondrial Uncoupling, ATP Synthase Rotary Mechanism, Light Reactions and ATP Synthesis. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Proton Motive Force?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Proton Motive Force. To practise the whole of Metabolism & Bioenergetics, use the Metabolism & Bioenergetics quiz.
How is Proton Motive Force different from Chemiosmosis?
Proton Motive Force: The combined chemical and electrical gradient of protons that powers ATP synthase and transport. Chemiosmosis: Protons flowing back through ATP synthase down their gradient drive the formation of ATP. Read both side by side and note what each one explains.
How should I study Proton Motive Force step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Chemiosmosis and explain the difference aloud. Finally, take the Metabolism & Bioenergetics quiz and come back to this page for any question you miss.