The cytochrome b complexes of the mitochondrion and the chloroplast have similar organization and function. They each pass electrons from a reduced quinone to a peripheral membrane protein, pumping protons across the membrane in the process, and contributing to the proton gradient that drives ATP synthesis. In the diagram below identify the components and the membrane orientation of each system by dragging the appropriate labels to their correct positions.

cytochrome b6f

cytochrome bc1

plastoquinol

plastocyanin

chloroplast stroma

thylakoid lumen

mitochondrial matrix

intermembrane space

cytochrome c

ubiquinol

ADP + Pi

ATP + H2O