ABSTRACT
Oxygenic photosynthesis is a biophysicochemical process that converts carbon dioxide into organic compounds using light as a source of energy. It occurs in plants, algae, and cyanobacteria, but not in archaea. Photosynthesis uses water as a source of electrons, releasing oxygen as a waste product. Photosynthesis confers autotrophy to organisms and is the only natural process, allowing for the creation of food from simple and abundant compounds. Therefore, this process is vital for all aerobic life forms on earth because, in addition to maintaining normal levels of oxygen in the atmosphere, photosynthetic products directly or indirectly constitute the ultimate source of energy in food. Regardless of the type of photosynthetic organism, this process takes place according to the same scheme (Merchant and Sawaya 2005). The photosynthetic apparatus is composed of four macrocomplexes, namely, water-oxidizing photosystem II (PSII), cytochrome b6f, photosystem I (PSI), and H+-translocating ATP synthase (CF0F1) (Nelson and Ben-Shem 2004). They supply ATP and NADPH for the synthesis of many essential compounds, such as carbohydrates, for autotrophic growth.
