Directly or indirectly, photosynthesis provides our entire food requirement, and many of our needs for fiber and building materials. The energy stored in petroleum, natural gas and coal all ultimately come from the sun via photosynthesis, as does the energy in firewood and other organic materials, which are major fuels in many parts of the world even in the present day. Thus, humans and other forms of life have existed, and exist today, due to performance of photosynthesis by plants, algae and cyanobacteria, which give Staurosporine nmr us oxygen, food, biomass, and bioenergy. This being the case, scientific

research into photosynthesis is vitally important if we are to maintain the demands of the ever-increasing population of our planet. Currently, it is estimated that photosynthesis produces more than 100 billion tons of dry biomass annually, which is equal to about 100,000 GW of stored energy. Furthermore, half of this activity occurs in the oceans. On a global scale, the raw materials and energy (e.g. water, carbon dioxide, this website sunlight) needed to drive the synthesis of biomass is available in massive quantities.

However, in different ecosystems one or more of these factors can be limiting for photosynthesis. At the heart of the reactions in photosynthesis is the splitting of water into oxygen and hydrogen, through a series of steps that start with absorption of sunlight by photosynthetic pigments. The oxygen produced from water oxidation is released into the atmosphere where it is available for combustion of fuels and

for us to breathe. The ‘hydrogen’ is not normally released into the atmosphere, but instead is combined with carbon dioxide not to make various types of organic molecules. When we burn fuels we combine the ‘stored hydrogen’ in these organic molecules with atmospheric oxygen; in other words, we use the products of photosynthesis to obtain energy required for sustaining our life. Understanding the reactions in photochemistry is crucial to the goal of making artificial photosynthesis, namely to utilize solar energy and convert it into chemical energy through a series of photo-electrochemical events. The design of such systems may benefit greatly from elucidation of the principles of the natural photosystems. Currently, we know a great deal about the workings of the two photosystems, including the water oxidation reaction and reactions of carbon assimilation. However, there are still many gaps in our understanding of photosynthesis, and thus in our ability to use knowledge of the process to benefit mankind.