What Happens in the Light Reaction of Photosynthesis?
What is Photosynthesis? Photosynthesis is a biological process by which energy contained within light is converted into chemical energy of bonds between atoms that power processes within cells. It is the reason Earth’s atmosphere and seas contain oxygen. Photosynthesis occurs today within a variety of single-celled organisms as well as in plant cells (in specialized organelles called chloroplasts). There are two stages of photosynthesis: the light reactions and the dark reactions. Oxidation and Reduction Compared to sugars such as glucose, carbon dioxide (CO2) is a low-energy chemical compound. CO2 is highly “oxidized” compared to a glucose, which is more “reduced.” When a chemical compound, such as CO2 gains electrons, it becomes less oxidized and more reduced, and this means that it holds more energy that can be used in cells. In fact, the electrons are what holds the chemical energy. Thus, as CO2 molecules are changed chemically, carbon atoms are joined together, forming glucose, wh
