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Topic: Photophosphorylation

	Photosynthesis: The Role of Light
		Because it is drive by light, this process is called photophosphorylation.
		It is also called noncyclic photophosphorylation because it produces ATP in a one-way process (unlike cyclic photophosphorylation and pseudocyclic photophosphorylation described below).
		Some workers believe that cyclic photophosphorylation is simply an artifact of the preparations studied in the laboratory.
	users.rcn.com /jkimball.ma.ultranet/BiologyPages/L/LightReactions.html (1142 words)

	Light-dependent reaction - Wikipedia, the free encyclopedia
		The light reaction also generates ATP by powering the addition of a phosphate group to ADP, a process called photophosphorylation.
		This pathway is known as cyclic photophosphorylation, and it produces neither O
		The other pathway, noncyclic photophosphorylation, is a two-stage process involving two different chlorophyll photosystems.
	zope.gnowledge.org /Wiki_Encyclopedia/Data/Objects/1/181674 (898 words)

	Photosynthesis
		Photophosphorylation is the process of converting energy from a light-excited electron into the pyrophosphate bond of an ADP molecule.
		Photophosphorylation consists of two pigments to excite, called PS1 (photosystem 1) and PS2 (photosystem 2).
		Photophosphorylation occurs when the electrons from water are excited by the light in the presence of P680.
	www.angelfire.com /ak2/chemists/leah7.html (872 words)

	Water Quality Guidelines Online - Water: The Hub of Life - Key Features of Living Things - Electron Transport Chains
		In non-cyclic photophosphorylation there is a one-way flow of electrons, ultimately from water to NADP+.
		With cyclic photophosphorylation the pathway is cyclic because excited electrons that originate from the pigment at the reaction center eventually return to it.
		Cyclic photophosphorylation occurs in plant cells when there is too little NADP+ to accept electrons from ferredoxin.
	www.ozh2o.com /h2life4.html (1451 words)

	Botany: Photosynthesis (Site not responding. Last check: )
		In non-cyclic photophosphorylation both photosystems are used and there is a one-way flow of electrons, ultimately from water to NADP+.
		With cyclic photophosphorylation only Photosystem I is involved, and the pathway is cyclic because excited electrons that originate from P700 at the reaction center eventually return to P700.
		Cyclic photophosphorylation occurs in plant cells when there is too little NADP+ to accept electrons from ferredoxin.
	www.bergen.org /AAST/Projects/Botany/photo.html (769 words)

	Summary, WAU dissertation no. 488
		Oxygen evolution was measured with the aid of the WARBURG technique, the suspension medium mostly was WARBURG buffer no 9, the gas phase was air, in general, the temperature 25°C. Cyclic photophosphorylation was determined by measuring inorganic phosphate uptake by the algae during a 90 minutes illumination period under a nitrogen atmosphere.
		With respect to the mechanism of photosynthesis it is concluded that cyclic photophosphorylation occurs also in vivo.
		Evidence suggests that there are two phosphorylation sites in the cyclic electron transport chain: one between cytochrome 559 and cytochrome 553, and another one in the chain of PS I between Z and plastoquinone.
	library.wur.nl /wda/abstracts/ab488.html (767 words)

	Botany online: Photosynthesis - Light Reactions
		To the right: the original concept of non-cyclic photophosphorylation (according to D. The only unexplained process remained was the photoreduction of NADP in chloroplasts.
		It were again ARNON and his collaborators that were in 1957 able to discover a second part of photophosphorylation.
		In contrast to the cyclic photophosphorylation is the production of ATP coupled stoichiometric to a light-induced transfer of electrons from water to NADP and to the production of oxygen.
	www.biologie.uni-hamburg.de /b-online/e24/24c.htm (1605 words)

	IngentaConnect Photophosphorylation and the chemiosmotic perspective (Site not responding. Last check: )
		Photophosphorylation was discovered in chloroplasts by D. Arnon and coworkers, and in bacterial `chromatophores' (intercytoplasmic membranes) by A. Frenkel.
		Isolation and analysis of the ATP synthase showed, as with mitochondrial and bacterial analogues, an intrinsic membrane complex (CF) and an extrinsic complex (CF is a latent ATPase, activated additively by the high-energy state of the thylakoids, and by reduction of a disulfide bond on the gamma subunit.
		Chemiosmosis was confirmed in several ways, including ATP synthesis in the dark due to an acid-to-base transition of thylakoids, and photophosphorylation accomplished in artificial lipid vesicles containing both the proton-pumping bacterial rhodopsin and a mitochondrial ATPase complex.
	www.ingentaconnect.com /content/klu/pres/2002/00000073/F0030001/00407559 (307 words)

	Chapter 10
		Summarize the carbon-fixing reactions of the Calvin cycle and describe changes that occur in the carbon skeleton of the intermediates.
		This process is called photophosphorylation because the energy required is light.
		His experiments demonstrated that during photophosphorylation, the function of the photosystems and the electron transport chain is to create a proton-motive force that drives ATP synthesis.
	www.niles-hs.k12.il.us /jacnau/chpt10.html (5729 words)

	Press Release: The 1978 Nobel Prize in Chemistry
		The processes by which ATP is formed from ADP and Pi during photosynthesis and respiration are usually called 'photophosphorylation' and 'oxidative phosphorylation', respectively.
		In higher cells, photophosphorylation and oxidative phosphorylation occur in specific membrane-enclosed organelles, chloroplasts and mitochondria, respectively; in bacteria, both these processes are associated with the cell membrane.
		In addition, this concept of biological power transmission by protonmotive force (or 'proticity', as Mitchell has recently began to call it in an analogy with electricity) has already been shown to be applicable to other energy-requiring cellular processes.
	nobelprize.org /nobel_prizes/chemistry/laureates/1978/press.html (743 words)

	Photophosphorylation
		Photophosphorylation (def) uses the radiant energy of the sun to drive the synthesis of ATP.
		Light energy activates chlorophyll causing it to transfer an electron to an electron transport chain and, in the process, produce ATP from ADP and inorganic phosphate.
		Photophosphorylation will be discussed in greater detail under photosynthesis.
	student.ccbcmd.edu /~gkaiser/biotutorials/energy/photoph.html (61 words)

	13
		This electron flow is "coupled" to the formation of ATP in both cyclic and non-cyclic pathways; in addition, NADP is reduced in the non-cyclic pathway.
		Non-cyclic photophosphorylation is initiated by light shining on photosystems 1 Andean.
		In cyclic photophosphorylation, electrons, from cytochrome complex are recycled back to P 700 via the chain of electron carriers.
	www.nos.org /bio12/b2h13.1.htm (2919 words)

	Procaryotic Metabolism
		This universal mechanism of cyclic photophosphorylation is referred to as Photosystem I.
		The light energy is used to boost the electron to a low redox intermediate, ferredoxin, (or some other iron sulfur protein) which can enter electrons into the photosynthetic electron transport system in the membrane.
		In plant photosynthesis, chlorophyll a is the major chlorophyll species at the reaction center and the exact nature of the primary electron acceptors (X or ferredoxin) and the components of the ETS are different than bacterial photosynthesis.
	textbookofbacteriology.net /metabolism.html (8689 words)

	The Diversity of Metabolism in Procaryotes
		Photosystem I and the mechanisms of cyclic photophosphorylation operate in plants, algae and cyanobacteria, as they do in bacterial photosynthesis.
		In plant photosynthesis, chlorophyll a is the major chlorophyll species at the reaction center and the exact nature of X and the components of the ETS are different than bacterial photosynthesis.
		Most of the phototrophic procaryotes are obligate or facultative autotrophs, which means that they are able to fix CO2 as a sole source of carbon for growth.
	dwb.unl.edu /Teacher/NSF/C11/C11Links/www.bact.wisc.edu/Bact303/bact303metabolism (8097 words)

	BCH/PPA 503 \| Lecture Six Web Notes
		The Z scheme and photophosphorylation were overviewed in Lecture 2.
		This overall process is known as acyclic photophosphorylation.
		This photophosphorylation is carried out by a 4
	www.uky.edu /~dhild/biochem/6/lect.html (310 words)

	Photophosphorylation
		This Proton gradient can be used to generate ATP chemiosmotically.
		the electrons are recycled, hence the name cyclic photophosphorylation.
		The electrons are using to translocate Protons which the ATPase
	bioweb.wku.edu /courses/Biol120/images/Photophosphryl.htm (293 words)

	Photophosphorylation (Site not responding. Last check: )
		Stimulation of Photophosphorylation by Ascorbate as a Function of Light Intensit...
		Re: The fate of the electron in cyclic photophosphorylation in photosynthesis...
		Outline for Chpater 19: Oxidative Phosphorylation and Photophosphorylation...
	www.scienceoxygen.com /biology/128.html (112 words)

	COORDINATING PHOTOSYNTHETIC ACTIVITY: CIRCADIAN RHYTHMS
		The two pathways of photosynthesis, photophosphorylation and the Calvin-Benson Cycle, proceed within the chloroplast.
		Because photophosphorylation requires light energy to proceed, both pathways of photosynthesis stop in the dark.
		It is therefore beneficial for plants to coordinate their photosynthetic activity and stomata activity with daily changes in light availability.
	www.tiem.utk.edu /~gross/bioed/webmodules/circadianrhythm.html (1553 words)

	Photosynthesis Terminology
		There are two pathways, or photosystems, which harvest light and produce reduced products.
		Noncyclic photophosphorylation: pathway utilizing both photosystem I and II.
		Cyclic photophosphorylation: energy harvested by photosystem II only.
	web.bio.utk.edu /kelly/photosynthesis_terminology.htm (416 words)

	Bio 21 Supplemental Study Guide for Exam 2 (3/14) (Site not responding. Last check: )
		Explain how noncyclic photophosphorylation balances NADPH and ATP production to meet requirements of the Calvin cycle.
		Distinguish between substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation.
		Describe important differences in chemiosmosis between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts.
	www.macalester.edu /~montgomery/terms4.html (281 words)

	Courses: BIO111-General College Biology I: Chapter 10 Outline
		The light reaction is broken down into two components, cyclic and non- cyclic photophosphorylation.
		Cyclic Photophosphorylation: As you saw in the last section, non-cyclic photophosphorylation produces equal quantities of ATP and NADPH.
		Non-cyclic photophosphorylation utilizes P680, while cyclic utilizes p700.
	www.colorado.edu /MCDB/MCDB3120/outlines/old/ch10.html (720 words)

	The changes in ATPase activity of the coupling factor of photophosphorylation in etiolated pea leaves under red and ... (Site not responding. Last check: )
		The changes in ATPase activity of the coupling factor of photophosphorylation in etiolated pea leaves under red and blue light
		The activity of CA2+- and MG2+-dependent ATPase of the coupling factor of photophosphorylation in etiolated pea leaves during their greening under white, red or blue light for 2 h was investigated.
		There was little effect of white, red or blue light on Mg2+-dependent ATPase activity.
	olericulture.org /000/432/000432449.html (113 words)

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