PCC 7942. *Response times vary by subject and question complexity. Cyclic electron flow (CEF) is a crucial component of photosynthesis in both plants and cyanobacteria. Recent studies show that the cyclic electron flow can operate under aerobic conditions and support a simple competition model where the excess reducing power is recycled to match the demand for ATP. Light adaptation of cyclic electron transport through Photosystem I in the cyanobacterium Synechococcus sp. All three pathways are necessary for poised and sustained synthesis of ATP and NADPH and their interplay enables the flexibility of photosynthesis … In the thylakoid reactions, electrons excised from water in PSII are transferred to NADP + through the cytochrome b 6 f complex and PSI, resulting in the production of NADPH. The light-driven reaction of photosynthesis also called light reaction (Hill reaction), referred to as electron transport chain, were first propounded by Robert Hill in 1939. Three major electron transfer pathways known are linear, cyclic and pseudo-cyclic electron transfer (LEF, CEF and PCEF, respectively). B) It changes the direction of... See full answer below. However, recent genetic approaches using Arabidopsis thaliana have clarified the essential functions of this electron flow in both photoprotection and photosynthesis. The electron transport chain of photosynthesis is initiated by absorption of light by photosystem II (P 68o). However, up to now, it was not clear how it differs … Photosynthesis consists of a series of electron transport reactions in the thylakoid membrane and carbon fixation reactions in the stroma. Linear electron transport generates both ATP and NADPH, whereas PSI cyclic electron transport produces ATP without producing NADPH. Differences between the supply of ATP from linear electron transport and an increased demand could be balanced via cyclic electron flow (Kramer and Evans, 2011; Walker et al., 2014; Yamori et al., 2016). Photosynthesis Research 1995 , 46 (1-2) , 277-285. Cyclic electron transport in photosynthesis is required when the total demand for ATP exceeds the demand for ATP in basic CO 2 fixation reactions. True, cyclic electron transport only uses the P700 photosystem. FIGURE 1: Overall reaction of photosynthesis Chemical Equation for photosynthesis process: 6CO 2 + 12H 2 PHOTOSYNTHESIS The conversion of light energy to chemical energy that is stored in sugar or other organic compound using CO 2 and water (occurs in plants, algae & certain unicellular eukaryotes and some prokaryotes). The parsing of the proton-motive force between ΔpH and Δψ, regulated in many different ways (cyclic electron flow, ATPsynthase conductivity, ion/H+ transporters), is comprehensively reported. Median response time is 34 minutes and may be longer for new subjects. The light reactions in photosynthesis drive both linear and cyclic electron transport around photosystem I (PSI). 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