Photosynthesis Again...Dark Reactions

Earlier in the week I discussed the topic of photosynthesis, but never touched upon the topic of dark and light reactions. The photosynthesis reaction can be broken into two seperate sub-reactions, light and dark. As described by its name the light reactions gain their energy and are activated by light photons. As the intesity of light increases the amount of products produced, speed and efficiency of the reaction are increase. The light reactions involve two photosystems connected by an electron transport chain, these two systems function optimally at 680nm and 720nm light wavelegths.The dark reactions on the other hand, are considered to function independently from it, meaning they do not need photon energy of any sort to produce products. The process of the reaction is the Calvin cylce, which invovles the fixation of carbon into carbohydrates and the dissacotiation of water. This carbon fixation occurs in the stroma and requires NADPH and ATP in order to occur effectively. The ATP and NADPH the dark reactions use are the products of the light reaction, therefore without the light reactions and in turn the presence of light, the dark reactions would cease to occur because of their use of the ATP and NADPH.