Chemistry for Biologists: Photosynthesis
Photosynthesis is the process that enables higher plants, algae and a broad class of bacteria to transform light energy and store it in the form of energy‐rich organic molecules. In plants and algae, as well as some species of bacteria, photosynthesis removes carbon dioxide from the atmosphere, produces the molecular oxygen we breath and stores energy in biomass. In addition some bacteria use light energy to create energy‐rich molecules, but do not split water to produce oxygen. Photosynthesis is finely regulated to avoid damage caused by excess solar energy. At the same time, though, this regulation also decreases the efficiency of photosynthesis. Current research is aimed at understanding these responses to improve photosynthetic efficiency, thus increasing the production of food and fuel.
Photorespiration (article) | Photosynthesis | Khan Academy
Algae are a very diverse group of predominantly aquatic photosynthetic organisms that account for almost 50% of the photosynthesis that takes place on Earth. Algae have a wide range of antenna pigments to harvest light energy for photosynthesis giving different types of algae their characteristic colour. Early work done with algae contributed much to what is presently known about the carbon dioxide fixation pathway and the light harvesting reactions. The processes of photosynthesis in algae and higher plants are very similar. From among the three types of carbon dioxide‐concentrating mechanisms known in photosynthetic organisms, two types are found in different types of algae. Algae are proposed to play a role in the global carbon cycle by helping remove excess carbon dioxide from the environment. Recently, algae are recognized as a promising biodiesel source due to its efficient absorption and conversion of solar energy into chemical energy.
C2 photorespiration cycle; C3 photosynthetic carbon reduction cycle; C4 photosynthetic pathway and CAM; light‐harvesting complex; photosystem I; photosystem II
Learn About Photosynthesis Formula - ThoughtCo
Baker N, Harbinson J and Kramer DM (2007) Determining the limitations and regulation of photosynthetic energy transduction in leaves. Plant, Cell & Environment 30: 1107–1125.
The Power of Photosynthesis | Helix Magazine
Kramer DM, Avenson TJ and Edwards GE (2004) Dynamic flexibility in the light reactions of photosynthesis governed by both electron and proton transfer reactions. Trends in Plant Science 9: 349–335.
Artificial photosynthesis - Wikipedia
The C4 photosynthetic carbon metabolism pathway suppresses photorespiration by concentrating carbon dioxide at the site of carboxylation by Rubisco. The C4 pathway involves two different cell types, mesophyll cells and bundle sheath cells. Shown in the C4 cycle are: carboxylation of carbon dioxide into a four‐carbon acid in mesophyll cells; transport of the four‐carbon acid into bundle sheath cells; decarboxylation of the four‐carbon acid producing a high concentration of carbon dioxide within bundle sheath cells where the C3 cycle produces carbohydrate; transport of the resulting three‐carbon acid back to the mesophyll cell; and the regeneration of the carbon dioxide acceptor, PEP.
The Light Reactions of Photosynthesis
Behrenfeld MJ, Bale A, Kolber Z, Aiken J and Falkowski PG (1996) Confirmation of iron limitation of phytoplankton photosynthesis in the equatorial Pacific Ocean. Nature 383: 508–511.
The Calvin cycle (article) | Photosynthesis | Khan Academy
More interestingly, the dhurrin P450s were used to demonstrate that it is possible for P450s to obtain electrons directly from the photosynthetic apparatus. Eukaryotic P450s are normally located in the endoplasmic reticulum and rely on a NADPH-dependent dedicated oxidoreductase as a redox partner. However, in vitro and in vivo experiments have shown that if the P450s localize in the proximity of the photosystem I, they can retain activity by gaining electrons from photoreduced ferredoxin, thus bypassing the specialized reductase requirement. Since this concept worked quite well in plant chloroplasts, the researchers saw no reason that this principle is not transferable to cyanobacteria.
Photosynthesis's Purple Roots - Scientific American
Schematic drawing showing part of a chloroplast. The thylakoid membrane contains the major protein complexes of the photosynthetic machinery responsible for light absorption and electron and proton transfer. The reactions of the thylakoid membrane drive the C3 photosynthetic carbon reduction cycle that takes place in the chloroplast stroma. Illustrated is the concept of light‐driven linear electron flow coupled with the accumulation of protons in the thylakoid lumen, which is in turn used to drive ATP formation by the ATP synthase. In addition to the energy stored in ATP formation, energy derived from absorbed light is stored by the reactions of the thylakoid membrane in the formation of NADPH. Photosynthetic carbon reduction is shown as a three‐stage cycle. (1) Carboxylation: a molecule of carbon dioxide is covalently linked to a carbon skeleton. (2) Reduction: energy in the form of NADPH and ATP is used to form simple carbohydrate. (3) Regeneration: energy in the form of ATP is used to regenerate the carbon skeleton for carboxylation. Key: PS II, photosystem II; PS I, photosystem I; PQ and PQH2, plastoquinone and reduced plastoquinone; cyt, cytochrome; FeS, Rieske iron–sulfur protein; PC, plastocyanin; Fd, ferredoxin; FNR, ferredoxin‐NADP reductase.