Life on Earth as we know it depends on photosynthesis. In this process, plants, algae and cyanobacteria use solar energy to convert water and carbon dioxide into the oxygen we breathe and the glucose that fuels many biological processes (Blankenship, 2002).
The photosynthetic machinery is made from an intricate and complicated collection of protein complexes containing mainly chlorophyll a molecules and carotenoid molecules. Several of these complexes work together in a synchronised fashion to accomplish an amazing feat: to split water molecules (one of the most stable molecules on earth) to extract electrons and produce oxygen, and to transfer electrons to quinone molecules so that photosynthesis can continue. The efficiency of this initial energy-conversion step determines the outcome of the whole process.