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Original - "Cyanobacteria" edit
Photosynthesis edit
While contemporary cyanobacteria are linked to the plant kingdom as descendants of the endosymbiotic progenitor of the chloroplast, there are several features which are unique to this group.
Electron transport edit
In contrast to purple bacteria and other bacteria performing anoxygenic photosynthesis, thylakoid membranes of cyanobacteria are not continuous with the plasma membrane but are separate compartments.[1]
While most of the high-energy electrons derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via electrogenic activity.[2]
Metabolism and organelles edit
As prokaryotes, cyanobacteria do not have nuclei. In most forms, the photosynthetic machinery is embedded into internal membrane structures called thylakoids. Cyanobacteria get their colour from the bluish pigment phycocyanin, which assists chlorophyll in photosynthesis. In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide[3] a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria. Carbon dioxide is reduced to form carbohydrates via the Calvin cycle.[citation needed]The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria.[citation needed] They are often found as symbionts with a number of other groups of organisms such as fungi (lichens), corals, pteridophytes (Azolla), angiosperms (Gunnera), etc.[citation needed]
Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). In anaerobic conditions, they are able to use only PS I—cyclic photophosphorylation—with electron donors other than water (hydrogen sulfide, thiosulphate, or even molecular hydrogen[4]) just like purple photosynthetic bacteria. Furthermore, they share an archaeal property, the ability to reduce elemental sulfur by anaerobic respiration in the dark. Their photosynthetic electron transport shares the same compartment as the components of respiratory electron transport. Their plasma membrane contains only components of the respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electron transport chain.[citation needed] The terminal oxidases in the thylakoid membrane respiratory/photosynthetic electron transport chain are essential for survival to rapid light changes, although not for dark maintenance under conditions where cells are not light stressed.[5]
Edits - "Cyanobacteria" (After Peer Review) edit
Peer review responses
I received two peer review responses, and decided to take a look at the feedback from both of them.
For the feedback from Grobbin5, they suggested that I remove the "Electron transport" title under the assumption that photosynthesis is sufficient enough for the following paragraphs, however I disagree. For a specialist in the field photosynthesis alone is definitely sufficient for referring to electron transport, however someone without much prior knowledge of the chemical and molecular mechanisms of photosynthesis would benefit from having "Electon transport" specified. It also leaves the paper in a similar structure to how I found it, which was good in the past. Other feedback incorporated.
For the feedback from Kimwayne, I moved the respiration subsection beside the electron transport chain subsection. However with their recommendation of changing "photosynthesis" to "carbon cycle & respiration", it seems more simple to just leave it as photosynthesis, which is a defining factor of Cyanobacteria. I'm not sure of what citations lack proper sources, aside from those that say "[citation needed]" which were already present in the original article.
- Adam Mesa (talk) 04:07, 20 November 2017 (UTC)
Photosynthesis edit
While contemporary cyanobacteria are linked to the plant kingdom as descendants of the endosymbiotic progenitor of the chloroplast, there are several features which are unique to this group.
Electron transport edit
In contrast to purple bacteria and other bacteria performing anoxygenic photosynthesis, thylakoid membranes of cyanobacteria are not continuous with the plasma membrane but are separate compartments.[1] The photosynthetic machinery is embedded in the thylakoid membranes, with phycobilisomes acting as light-harvesting antennae attached to the membrane, giving the green pigmentation observed (with wavelengths from 450nm to 660nm) in most cyanobacteria.[6]
While most of the high-energy electrons derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via electrogenic activity.[2]
Respiration edit
Respiration in cyanobacteria can occur in the thylakoid membrane alongside photosynthesis,[7] with their photosynthetic electron transport sharing the same compartment as the components of respiratory electron transport. While the goal of photosynthesis is to store energy by building carbohydrates from CO2, respiration is the reverse of this, with carbohydrates turned back into CO2 accompanying energy release.
Cyanobacteria appear to separate these two processes with their plasma membrane containing only components of the respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electron transport chain.[7] Cyanobacteria use electrons from succinate dehydrogenase rather than from NADPH for respiration.[7]
Electron transport chain edit
Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). In contrast to green sulfur bacteria which only use one photosystem, the use of water as an electron donor is energetically demanding, requiring two photosystems.[8]
Metabolism edit
In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide[3] a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria.
Carbon dioxide is reduced to form carbohydrates via the Calvin cycle.[citation needed] The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria.[9] They are often found as symbionts with a number of other groups of organisms such as fungi (lichens), corals, pteridophytes (Azolla), angiosperms (Gunnera), etc.[citation needed]
Removed some paragraphs and subsections from this section that weren't edited, for clarity - Adam Mesa (talk) 04:07, 20 November 2017 (UTC)
Edits - "Cyanobacteria" (Before Peer Review) edit
Photosynthesis edit
While contemporary cyanobacteria are linked to the plant kingdom as descendants of the endosymbiotic progenitor of the chloroplast, there are several features which are unique to this group.
Electron transport edit
In contrast to purple bacteria and other bacteria performing anoxygenic photosynthesis, thylakoid membranes of cyanobacteria are not continuous with the plasma membrane but are separate compartments.[1] The photosynthetic machinery is embedded in the thylakoid membranes, with phycobilisomes acting as light-harvesting antennae attached to the membrane, giving the pigmentation (from 450 to 660nm) in most cyanobacteria.[6]
While most of the high-energy electrons derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via electrogenic activity.[2]
Respiration edit
Respiration in cyanobacteria can occur in the thylakoid membrane alongside photosynthesis,[7] with their photosynthetic electron transport sharing the same compartment as the components of respiratory electron transport. While the goal of photosynthesis is to store energy by building carbohydrates from CO2, respiration is the reverse of this, with carbohydrates turned back into CO2 accompanying energy release.
Cyanobacteria appear to separate these two processes with their plasma membrane containing only components of the respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electron transport chain.[7] Cyanobacteria use electrons from succinate dehydrogenase rather than from NADPH for respiration.[7] - Adam Mesa (talk) 00:45, 9 October 2017 (UTC)
Metabolism edit
In general, photosynthesis in cyanobacteria uses water as an electron donor and produces oxygen as a byproduct, though some may also use hydrogen sulfide[3] a process which occurs among other photosynthetic bacteria such as the purple sulfur bacteria. - Adam Mesa (talk) 00:45, 9 October 2017 (UTC) Carbon dioxide is reduced to form carbohydrates via the Calvin cycle.[citation needed] The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria.[9] They are often found as symbionts with a number of other groups of organisms such as fungi (lichens), corals, pteridophytes (Azolla), angiosperms (Gunnera), etc.[citation needed]
Electron transport chain edit
Many cyanobacteria are able to reduce nitrogen and carbon dioxide under aerobic conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of photosystem (PS) II and I (Z-scheme). In contrast to green sulfur bacteria which only use one photosystem, the use of water as an electron donor is energetically demanding, hence the two photosystems.[8]
-- Removed some paragraphs and subsections from this section that weren't edited, for clarity - ~~~~
- ^ a b c Vothknecht, U. C.; Westhoff, P. (2001). "Biogenesis and origin of thylakoid membranes". Biochimica et Biophysica Acta (BBA) - Molecular Cell Research. 1541 (1–2): 91–101. doi:10.1016/S0167-4889(01)00153-7. PMID 11750665.
- ^ a b c Pisciotta JM, Zou Y, Baskakov IV; Zou; Baskakov (2010). Yang, Ching-Hong (ed.). "Light-Dependent Electrogenic Activity of Cyanobacteria". PLoS ONE. 5 (5): e10821. Bibcode:2010PLoSO...510821P. doi:10.1371/journal.pone.0010821. PMC 2876029. PMID 20520829.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) - ^ a b c Cohen Y, Jørgensen BB, Revsbech NP, Poplawski R; Jørgensen; Revsbech; Poplawski (1986). "Adaptation to hydrogen sulfide of oxygenic and anoxygenic photosynthesis among Cyanobacteria". Appl. Environ. Microbiol. 51 (2): 398–407. PMC 238881. PMID 16346996.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Champion Hydrogen-Producing Microbe, ScienceDaily, 15 December 2010
- ^ Lea-Smith, D. J.; Ross, N.; Zori, M.; Bendall, D. S.; Dennis, J. S.; Scott, S. A.; Smith, A. G.; Howe, C. J. (5 March 2013). "Thylakoid Terminal Oxidases Are Essential for the Cyanobacterium Synechocystis sp. PCC 6803 to Survive Rapidly Changing Light Intensities". Plant Physiology. 162 (1): 484–495. doi:10.1104/pp.112.210260. PMC 3641225. PMID 23463783.
- ^ a b Sobiechowska-Sasim Monika, Stoń-Egiert Joanna, Kosakowska Alicja (February 2014). "Quantitative analysis of extracted phycobilin pigments in cyanobacteria—an assessment of spectrophotometric and spectrofluorometric methods". J Appl Phycol. 26: 2065–2074 – via ProQuest.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ a b c d e f Vermaas, Wim FJ (2001). Photosynthesis and Respiration in Cyanobacteria. eLS. John Wiley & Sons, Ltd. doi:10.1038/npg.els.0001670. ISBN 9780470015902.
- ^ a b Klatt, Judith M.; de Beer, Dirk; Häusler, Stefan; Polerecky, Lubos (2016). "Cyanobacteria in Sulfidic Spring Microbial Mats Can Perform Oxygenic and Anoxygenic Photosynthesis Simultaneously during an Entire Diurnal Period". Frontiers in Microbiology. 7. doi:10.3389/fmicb.2016.01973. ISSN 1664-302X.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ a b Och, Lawrence M.; Shields-Zhou, Graham A. "The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling". Earth-Science Reviews. 110 (1–4): 26–57. doi:10.1016/j.earscirev.2011.09.004.