Answer:
If an uncoupler is added to the intermembrane space of a mitochondrion, it will affect both ATP synthesis and electron transport in the following ways:
a) ATP Synthesis:
Uncouplers allow protons (H+) to freely move across the membrane, bypassing the ATP synthase enzyme. This disrupts the chemiosmotic gradient that drives ATP synthesis. As a result, the energy from the electron transport chain is no longer used effectively to generate ATP. While electron transport may continue, ATP synthesis becomes uncoupled from it. This leads to a decrease or complete cessation of ATP synthesis.
b) Electron Transport:
Uncouplers disrupt the proton gradient (proton motive force) that builds up across the mitochondrial inner membrane during electron transport. They increase the permeability of the membrane to protons, allowing protons to freely flow back into the matrix without passing through the ATP synthase. This bypassing of the ATP synthase causes the electron transport chain to continue functioning independently of ATP synthesis. As a result, electron transport can still occur, allowing the flow of electrons through the chain, while ATP production is significantly reduced.
In summary, the presence of an uncoupler in the intermembrane space of a mitochondrion will lead to a decoupling of ATP synthesis and electron transport. While electron transport can still occur, the energy normally used for ATP synthesis is dissipated as the protons freely move across the membrane, thus greatly reducing or halting ATP production.