Talk:Light-dependent reactions

photophosphorylation = Light-dependent reaction?

For some reason, the photophosphorylation article is re-directed into Light-dependent reaction article. The two, in my opinion are not the same and therefore shouldn't be linked. The former is more tightly related to plants, while the later can in fact be applied even to photovoltaic cells (solar cells)

It would be a good idea to expand the Light-dependent reaction article to include non-biological examples of this, but keep the redirect (as otherwise it would just be duplication of content). Or perhaps it would be better to turn the light-dependent reaction page into a disambiguation page. Thoughts? Talrias 10:35, Feb 5, 2005 (UTC)

Photovoltaic cells do not phosphorylate anything. There's more to the light reactions than photophosphorylation, but the redirect seems appropriate to me. dsws 02:27, 12 July 2005 (UTC)

Is NADPH considered as stored energy?

Just wondering , because all the sources I found so far states that it is just a reducing agent (but it did not say it's not an energy store). But isn't it also chemical energy then?

---NADPH is also an energy storing molecule, yes.

---It is a reducing agent; however, it has a rather highly negative reduction potential -- that is to say, its oxidation is very thermodynamically downhill. Therefore, NADPH can transfer electrons to chemicals that are not normally easy to reduce. This includes CO2 in the Calvin-Benson cycle. It also explains how so much energy becomes available to pump protons to mitochondrial ETC reactions where the reducing power of NADH is coupled to many uphill reactions. —Preceding unsigned comment added by 128.12.246.246 (talk) 02:18, 14 December 2009 (UTC)

Step 7

curious as to why it says "SENS RULE!!" after number 7 in the steps section... it could be vandalism considering i've never heard of any such thing and i doubt it has anything to do with the calvin-benson cycle.Annie 02:23, 27 November 2006 (UTC)

--- it was vandalism, so i removed it.

this doesnt help :( — Preceding unsigned comment added by 2602:306:BD30:1820:5140:DC60:D9CE:61AB (talk) 01:28, 1 December 2016 (UTC)

Cyclic photophosphorylation

I think this discription contains a mistake stating: "passes from the primary acceptor to ferredoxin, then to a complex of two cytochromes (similar to those found in mitochondria), and then to plastoquinone before returning to chlorophyll". It is supposed to be plastocyanin that carries the electrons back to the PS1, isn't it?

jeah, you are totally right. Ferredoxin can't gives electons to cytochrome b6f. I fixed it. (Kasper90 (talk) 01:03, 4 January 2009 (UTC))

The first figure (https://en.wikipedia.org/wiki/Light-dependent_reactions#/media/File:Thylakoid_membrane_3.svg) and accompanying description do not clearly show how the electrons are recycled so as to avoid the production of NADPH. This cyclic process is shown later on, but in less detail, in the animated figure (https://en.wikipedia.org/wiki/Light-dependent_reactions#/media/File:Light_Dependent_Cyclic_Reactions.gif). I lack the graphic arts skill to fix this myself, but if I am right, someone should change the figure and accompanying text to make the cyclic path clear, e.g. by adding a blue dotted arrow to represent electrons returning from PSI to PSII.CharlesHBennett (talk) 13:15, 19 January 2017 (UTC)

ET in photosynthesis is solid-state?

There appears to be a comment in this page that suggests electron-transfer in photosystem II should be considered a solid-state reaction. I vehemently disagree with this statement; however, I figured it would be more appropriate to bring it up in discussion rather than change it on my own. The contributor seems to think that because the protein arranges a crystalline state, it cannot be considered a chemical reaction. He/she goes further to say that chemistry is described by "random energy distributions." Both claims seem to me do be false. Yes, proteins pre-organize highly specific architecture, however that is entirely in the purview of supramolecular chemistry. If pre-organized architecture was equivalent to the solid-state, then every protein-mediated ET would need to be considered "solid-state," which makes a mockery of the long tradition of chemists who have studied ET in proteins through the molecular framework, and have used it both to understand results and predict phenomena. The solid-state facilitates electron transfer not simply because of rigid structure, but rather, because the solution to Schrödinger's Equation for a periodic potential reduces to Bloch waves, which reveals that the state in position space is unlocal and reduces to a Fermi gas. A protein might be rigid, but it is by no means macroscopically periodic. The efficiency of ET is a testament of supramolecular functionality. It looks like a solid-state physicist has sour grapes over photosynthesis. 128.12.246.246 (talk) 02:31, 14 December 2009 (UTC)

I understand that many have emotional comments about this article. I studied photsynthesis at UCB with Melvin Calvin (who described the first enzyme in the Calvin Cycle-RUDP carboxylase for which he earned a Nobel Prize) and Daniel Arnon who discovered photophosphorylation. This page needs to be edited and I can do it.

I also worked with Bob Buchanan at UCB who is a world expert on the dark reactions of photosysnthesis. I am credited with describing the first allosteric (regulatory) enzyme in the Calvin Cycle: Sedoheptulose 1,7 Bisphosphatase.

Regards,

Vicki Breazeazle — Preceding unsigned comment added by Vicki breazeale (talk • contribs) 00:21, 9 October 2013 (UTC)

Photoreduction?

The article starts with: The light-dependent reactions, or photoreduction, is the first stage.... Are the light-dependent reactions really called 'photoreduction'? One type of what the literature calls 'photoreduction' is the light-stimulated reduction of Mn(IV) to Mn(II) in for instance the euphotic zone of seawater. This process is unrelated to photosynthesis.

I suggest that we either remove the term 'photoreduction' as a substitute for 'light-dependent reactions', or please back up the usage with citations (if in doubt, put them here in the discussion). Hulten (talk) 12:19, 5 June 2014 (UTC)

Seems similar to what the oxygen-evolving complex does.{RGS 20/04/18} — Preceding unsigned comment added by 82.14.235.194 (talk) 13:29, 20 April 2018 (UTC)

Rename?

Possibly this article should be renamed? There are millions of light-dependent reactions, ranging from the silver halide reactions used in photographic film to the creation and destruction of ozone in the upper atmosphere, but this article only talks about a minor subset of these, the ones related to photosynthesis. Geoffrey.landis (talk) 13:44, 28 May 2019 (UTC)

I propose Light-dependent reactions in photosynthesis. An alternative might be simply "Light-dependent biological reactions." Geoffrey.landis (talk) 19:20, 20 August 2019 (UTC)

Split proposal

Wikipedia has several overlapping articles focused somewhat on photosynthesis. We need fewer better-curated articles, the goal of this split idea:

• this article title would become a redirect to photochemistry (which are light-dependent reactions, this very title)
• a lot of content would be relocated to photosystem
• Even photosystem is dubious value in view of photosynthesis, photosystem I, photosystem II, and probably many others.
• some of the problems here result from the creation of niche topics for homework.--Smokefoot (talk) 16:56, 18 March 2026 (UTC)

I miss this page. I'll check what's there on the main page of photosynthesis. PigeonShaman (talk) 15:41, 25 August 2026 (UTC)

Any suggestions welcome. The topic is dormant so far as Wiki editors are concerned: photochemistry (which inherited light-dependent reactions) has had zero substantive edits in the past 5 months.--Smokefoot (talk) 16:25, 25 August 2026 (UTC)

Yeah, maybe later. I'm currently updating the Dutch pages involving photosynthesis. We like to have the photosynthesis page as an overview page, with the individual sections linking to other main articles; one of which is Light-dependent pages.

It's got so much detail and basically too much to have it on the main photosynthesis page. Similar now for the english version. There's two paragraphs, which is a good amount, but the rest appears to be gone now by easy link. (apart from the Z-scheme and waterphotolysis). PigeonShaman (talk) 16:36, 25 August 2026 (UTC)

It looks like I led the merge of light-dependent reactions into photosystem. This article should redirect there, not to photochemistry. If more work is needed, I can help but my knowledge of photosynthesis is generic.--Smokefoot (talk) 16:38, 25 August 2026 (UTC)

It looks like? You've been having lapses?

Ok, I see you've changed the link. I've changed the placeholder too now.

I mean why wouldn't you rename Photosystem to Light-dependent reactions? You seem to have most of it down, except for ATP-synthase. PigeonShaman (talk) 17:10, 25 August 2026 (UTC)