Photosynthesis oxygenic

Current evidence indicates that the excess of oxygenic photosynthesis over respiration and decomposition produced the major fraction of the oxygen of the Earth s atmosphere. [The overall reaction for aerobic respiration and decomposition is the reverse of reaction (3).] Oxygenic photosynthesis has been dated to before 2Ga ago by some distinctive geological formations. One of these formations is the extensive banded iron formations, our chief economic source of iron, found in rocks dated to 2- 

There are some cyanobacteria, especially species of Oscillatoria, that can grow anaerobically and photo- 

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In cyanobacteria and the eukaryotic photosynthetic cells of algae and higher plants, HgA is HgO, as implied earlier, and 2 A is O,. The accumulation of O, to constitute 20% of the earth s atmosphere is the direct result of eons of global oxygenic photosynthesis. 

Green, B. R., and Dnrnford, D. G., 1996. The chlorophyll-carotenoid proteins of oxygenic photosynthesis. Annual Review of Plant Physiology and Plant Molecular Biology 47 685—714. 

Photoautotrophic organisms, such as algae, cyanobacteria, and plants, all contain chlorophyll a and obtain energy by a process known as oxygenic photosynthesis. The overall chemical reaction of this process is ... 

Whereas the 2[4Fe-4S] ferredoxin may have been replaced by the [2Fe-2S] ferredoxins in oxygenic photosynthesis, another 2[4Fe-4S] protein, the so-called FA/FB-binding subunit (see Fig. 1), appears to be common to all RCI-type photosystems. 

A decade after the discovery of the Rieske protein in mitochondria (90), a similar FeS protein was identified in spinach chloroplasts (91) on the basis of its unique EPR spectrum and its unusually high reduction potential. In 1981, the Rieske protein was shown to be present in purified cytochrome Sg/complex from spinach (92) and cyanobacteria (93). In addition to the discovery in oxygenic photosynthesis, Rieske centers have been detected in both single-RC photosynthetic systems [2] (e.g., R. sphaeroides (94), Chloroflexus (95)) and [1] (Chlo-robium limicola (96, 97), H. chlorum (98)). They form the subject of a review in this volume. 

Cyanobacteria, prokaryotic algae that perform oxygenic photosynthesis, respond to a decrease in ambient growth temperature by desaturating the fatty acids of membrane lipids to compensate for the decrease in the molecular motion of the membrane lipids at low temperatures. During low-temperature acclimation of cyanobacterial cells, the desaturation of fatty acids occurs without de novo synthesis of fatty acids [110, 111]. All known cyanobacterial desaturases are intrinsic membrane proteins that act on acyl-Hpid substrates. 

Green, B.R. and Dunford, D.G., The chlorophyll-carotenoid proteins of oxygenic photosynthesis, Anmi. Rev. Plant Physiol. Plant Mol. Biol., 47, 685, 1996. 

If we look at evolution as a whole we will note that over 3.5 billion years, plant life has increased the ability to absorb energy from the Sun. However, only part of this energy is used to make ATP through a series of steps another part is used to make chemicals in the plant and a third part is used directly to oxidise the environment since 02 is produced in the process. This is the essence of oxygenic photosynthesis described in subsequent chapters and we may be interested in studying the... 

Fig. 6.5 Microbial iron and sulfur cycles that may have dominated biogeochemical cycling before the origin of oxygenic photosynthesis, aerobic respiration and possibly before the use of oxides of nitrogen.

Iverson, T.M. (2006) Evolution and unique bioenergetic mechanisms in oxygenic photosynthesis, Curr. Opin. Chem. Biol., 10, 91-100. 

Ultraviolet radiation (UVR) is a natural fraction of the solar radiation, and therefore has always influenced life in aquatic ecosystems. The development of oxygenic photosynthesis 2.5-2 J billion years ago (Holland 1984) led to drastic chemical changes in the Earth s oceans and atmosphere. The gradual increase in photosyn-thetically produced oxygen over millions of years was accompanied by a strong enrichment of it in the atmosphere, which ultimately acted as precursor for the ozone (03) layer in the stratosphere. 

Summons, R.E., L.L. Jahnke, J.M. Hope, and G.A. Logan. 1999. 2-methyl hopanoids as biomarkers for cyanobacterial oxygenic photosynthesis. Nature 400 554-557. 

Z-scheme of oxygenic photosynthesis in green algae cyanobacteria, showing links to hydrogenase... 

Figure 10.3 Z-scheme of oxygenic photosynthesis in green algae and cyanobacteria, showing links to hydrogenase. Q (plastoquinone) and X (an iron-sulfur cluster) are electron acceptors from photosystems II and I, respectively.The two hydrogenases shown are the NADP-dependent bidirectional hydrogenase and a ferredoxin-dependent enzyme.

Appel, J. and Schulz, R. (1998) Hydrogen metabolism in organisms with oxygeneic photosynthesis Hydrogenases as important regulatory devices for a proper redox poising. J. Photobiochem. PhotobioL, 47, 1-11. 

Continuum of metabolic strategies. AnAnP, anaerobic anoxygenic photosynthesis OP, oxygenic photosynthesis AAnP, aerobic anoxygenic photosynthesis RP/PC, rhodopsin and other pigments HT, heterotroph DOM, dissolved organic matter. Source-. From Filer, A. (2006). Applied Environmental MIoroblology, 42(12), 7431-7437. 

Role of Trace Metals in the Evolution of Oxygenic Photosynthesis... 

Cyanobacteria were probably the first organisms to perform oxygenic photosynthesis resulting eventually in the oxidation of environmental Fe " to Fe " with all its consequences. To cope with this problem the production of siderophores was initiated. Not much is known about the siderophores of cyanobacteria. Schizokinen (see below under citrate siderophores, Sect. 4.1) (326) found to be produced by several bacterial species may have been acquired by gene transfer see however also the citrate siderophores synechobactins. 

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