Talk:Electron transport chain

message: I think the ETC also exists in plastids (chloroplasts) and respiring bacteria. AdamRetchless 22:04, 9 Apr 2005 (UTC)
thread_title: Untitled

message: I have always heard this subject referred to as the Electron Transport Chain.  Is transfer more common?
 The article states "In most organisms the majority of ATP is generated in electron transport chains, while only some obtain ATP by fermentation.[citation needed]" Do we have any in vivo in situ justification for this statement?  We have lots of measurements made of ATP synthesized by isolated mitochondria, showing that they CAN make a lot of ATP, under certain conditions in a test tube (ie a reaction chamber equipped with an oxygen electrode and a few other things.) So we get values for P/O ratios under various conditions, and then extrapolate all the way back to the real world of whole organisms.  What we're doing is taking these P/O ratios and treating them like they were yields of ATP in vivo!  If that has ever been documented, fine.  (Bearing in mind that I don't want to spend my time plowing through textbooks and articles that mindlessly repeat the same mantra as summarized here in the Wikipedia statement I just quoted, supra; in vivo, please, as in "real world"; real organisms, and no weasel words neither, dangnabbit!Richard8081 (talk) 16:19, 3 October 2012 (UTC)
thread_title:  Name: transfer? chain 

message: why is it necessary to keep transferring electrons to so many carrier molecules? -- Bubbachuck 11:34, 23 December 2005 (UTC)
replies: text: I can't give a definite answer but it might be to spread the energy released as the electron goes from high energy to low energy over a number of steps, so that each step is a small release of energy that is more manageable to the organism. In addition to it being easier for all the energy to be picked up (increased efficiency), smaller redox potentials are less likely to cause the formation of reactive oxygen species that would be damaging to a mitochondria and the cell it's in. Just a guess. Philbradley 00:20, 15 June 2006 (UTC)
replies: text: My science textbook had an excellent way of putting it.  Suppose you had a flow of water at 1,000 feet.  If you had it fall those 1000 feet onto a waterwheel, you'd simply destroy your waterwheel.  If instead you had the water go down a cliff pushing several wheels as it went, you'd get more energy out of it. Mathwhiz90601 03:14, 30 May 2007 (UTC)

text: The problem is that none of these processes mentioned has sufficient Free energy to make one ATP. Therefore the work is divided into smallet steps and each step can pump a couple of protons and produce the pH gradient. However, the pH gradient is not sufficient to make one ATP either (because each step cannot make a large pH gradient by itself). Therefore the membrane potential comes into the picture. The membrane potential is made by pumping Na and K and other ions across the membrane. Now for each ATP syntheis, several protons and Na ions come back (down the concentraton gradient) and their total energy is used in making the ATP. This is one of the reasons that the ATP synthase is so complex (it looks and acts like a motor or generator). This will also explain why the number of ATP made per NADH or FADH2 is non-stochiometric (they simply work independently). Also Na ions need to be constantly pumped outside to maintain the membrane potential and this takes energy which is not included in the calculations.
I hope I am clear. chami 18:53, 30 May 2012 (UTC)
thread_title:  purpose of transferring electrons 

message: I added this image that I made. Do I need to go back and change Kreb cycle to Krebs cycle or perhaps Citric acid cycle?
Please tell me if there are any more errors in this drawing.—The preceding unsigned comment was added by Rozzychan (talk • contribs) .
:I think the use of alternate names is not a problem.  By the way, I enlarged the image so the small type would be easier to see. Hope no one minds.  Thanks for putting in this picture, it really adds a lot to the page! delldot | talk 05:20, 10 March 2006 (UTC)
thread_title:  Image 

message: This illustration greatly improves the overall visual appearance of the article.  Unfortunately, it is confusing, misleading, incomplete and factually incorrect.   There are at least 10 problems:
1. It should be labeled “Mitochondrial electron transport chain” to distinguish it from bacterial electron transport chains and photosynthetic electron transport chains, which are also discussed in the article.
2.  The upper membrane shows ATP synthase (so-called Complex V) off to the left.  ATP synthase is not part of the electron transport chain.  It is powered by a proton gradient, not by a series of redox reactions.  Many diagrams of mitochondria include it, but “Complex V” is misleading when the subject is “electron transport chains.”
3.  The upper membrane shows Complexes I and III connected by an arrow with an orange “II” floating overhead in the intermembrane space.  Mitochondrial Complex II is a transmembrane complex just like I, III and IV and should be depicted as such.
4.  Moreover, if this is intended to show the electron transport chain with NADH as the electron donor, “Complex II” does not belong here.  Complex I should be connected to Complex III by ubiquinone (Q). 
5.  Complex IV (which is unlabeled in the diagram) is shown connected to III by “cyto chrome” [sic].  Why not “cytochorome c,” or “cyt c”?  
6.  If “2H+ + ½ O2 → H20” is intended to represent a reduction, the arrow (which represents electrons) should join with the reactants, not cross over them.
7.  Moving onto the lower membrane, we see (in reverse logical order) the same bizarre “cross-reduction” diagram, Complex IV (unlabeled), “2e-” instead of “cytochrome c”, Complex III (unlabeled), and Complex I (unlabeled). Complex II is entirely missing.
If this is intended to represent the electron transport chain with FADH2 as the electron donor, Complex I should be omitted, II should be included and shown as connected to III by Q, “2e-” should be replaced by “Cyt c”, the final arrow should show a reduction, and the whole series should read left-to-right, not right-to-left. 
8.  Moving into the matrix, we find the “Kreb Cycle” (it’s “Krebs cycle”) floating off to the right between two arrows going around in a cycle.  If the Krebs cycle is included in this diagram, it should be shown as feeding NADH and FADH2 into the electron transport chain.
9.  A small point, but “high pH” and “low H+concentration” mean exactly the same thing.  Do we really need both captions in the diagram, or can we assume a basic familiarity with chemistry on the part of the reader?
10. Finally, the statement that “FADH2 pumps 2 protons across the membrane and makes 2 ATP, NADH pumps 3 protons across the membrane and makes 3 ATP” is simply false.  Complex I pumps 4 protons (per pair of electrons); Complex III pumps 4 protons, and Complex IV pumps 2 protons.  This gives 10 protons per NADH, 6 protons per FADH2.  ATP synthase needs 3 protons to produce one ATP; an additional proton is needed to transport the reactants (ADP and Pi) and products (ATP) across the membrane.  The ratio of ATP molecules produced per NADH (or per FADH2) is not an integer.
This article could be vastly improved by the inclusion of graphics, but the graphics should reflect our current knowledge of electron transport chains.  Excellent examples can be found in Lehninger and Voet.  Too bad about those copyright restrictions.
However, Wikipedians can probably do better anyway. Btarski 18:26, 17 March 2006 (UTC)
replies: text: I thank you for your diligence in spelling out your concerns. It sounds like you are an expert on the subject -- if you could put together a quick-and-dirty diagram and upload it to the commons, you would be doing us a great favor. However, until/unless we have a better image, I have added User:Rozzychan's image back, with a caveat underneath it addressing the limitations of the diagram. This is the approach usually used on Wikipedia when there is no replacement image currently available. But I do agree that if/when another Wikipedian is kind enough to build or donate an improvement (possibly adapting one of the others that are found on the sister wikis) it would be appropriate to incorporate many of your suggestions. --Arcadian 01:25, 18 March 2006 (UTC)
thread_title: Incorrect diagram

message: I finally got around to editing this page.
Thanks for the comments.
I addressed the listed points by number.
1. I thought that having the word Mitochondrion printed on the image would be sufficient to distinguish that this is the Mitochondrial ETC. I changed the title.
2. The ATP synthase is the main POINT of the ETC. I think that removing the ATP synthase confuses the student as to why the ETC exists at all. Also it was referenced in the article which is why I numbered it as I did, but since the article has been changed, I removed the V.
5. Writing cytochrome c without a space would be preferable, but then the font would be too small to read. I put a dash to make it more clear that this is a line wrap.
6. Done.
7. I disagree. Omitting complex I might confuse viewers. It is meant to be obvious that the complex shown on the bottom is the same one shown above for NADH. 
As to it reading from left to right instead of right to left. I am sorry but a membrane makes no such distinction. Also, reading directions are not the same for all viewers.
8. Yes I know it's Krebs. I mentioned this in a previous comment.
I don't want to go into detail for that cycle. How can I add this without needing to be accurate about the exact numbers that must feed into the cycle. I could remove the cycling arrows, but I don't think that would be clear.
9. No, I don't assume this familiarity by the reader. Beginning students are often confused on this point. I was trying to be clear to students who do not remember such facts immediately. This is a very important point. If I had to remove one, I would remove the pH.
10. This was a simplified note for beginning students, and I did not mean to leave it on this image.
Often we tell students inaccurate things because they are easier. When things do not come out as simple integers, students have a hard time understanding and remembering the point. Simple rules like this help a student understand. When they go on to more advanced studies, we tell them the earlier rule was slightly inaccurate.
However, since this is a dictionary entry, I have removed the text entirely and expect that you can mention the specifics of the reaction in the body of the article.
I changed the image to say that two protons were transferred due to the information shown on this website. 
http://www.elmhurst.edu/~chm/vchembook/596electransport.html
I have also included the source document (Etc2.svg).
Feel free to fix any small errors that you see.
Rozzychan
::The link you have shown is simply wrong. One NADH oxidation, whatever way that may be carried out, does not have sufficient energy to make three ATPs. 
Further, ATP synethesis is not coupled to the ET chain. ETC contributes to the pH gradient only.
ATP synthesis need both pH gradient and membrane potential. ATP synthase also carries Na ions downhill.
A table of standard free energies or redox potentials will be great help.
The article is too much simplified. The real process is somewhat complex.
chami 19:10, 30 May 2012 (UTC)
thread_title:  Modified Image 

message: there is nothing about how it is transported across the mito inner mem.
the shuttles i mean.--M siterman 09:22, 17 May 2006 (UTC)
thread_title:  NADH 

message: I understand that explaining the shuttles would be useful in understanding the difference between the 36ATP and 38ATP yield for the aerobic breakdown of glucose, however this does not directly impact on the function of the mitochondrial electron transport chain.
I agree that this is an important point though. 
I did not know about the shuttles until I had to teach this point, and realized that the numbers did not add up. A little online research clarified the point, but I still did not tell this to my most recent class, as this detail will only confuse beginning students.
More advanced students, however, are more disturbed by numbers that don't add up when they expect them too.
Suggestions:
1. Add a sentence saying that NADH from glycolysis enters the mitochondria through either the Glycerol phosphate shuttle (LINK) or the malate-aspartate shuttle (link).
This sentence should probably go onto another page though, I'm not sure which. Perhaps Oxidative phosphorylation
2. Make two new pages for those shuttles.
3. Make a glossary page that links to all pages discussing Aerobic and Anaerobic respiration.
Rozzychan 17:27, 23 June 2006 (UTC)
thread_title:  Shuttles in Oxidative phosphorylation 

message: This article seems to be redundant with many other articles in wikipedia. Since it is so long would it be wise to remove some of this information and rely on the other articles for more specific information? I am thinking of photosystems for one. David D. (Talk) 20:52, 16 June 2006 (UTC)
replies: text: I take this back.  i was looking at the other articles and they are not as complete as I had imagined. However there is a distinct lack of cross referencing to related articles especially in the photosynthesis related pages.  David D. (Talk) 20:57, 16 June 2006 (UTC)
thread_title: redundancy

message: To combat the feelings of redundancy and inadequate cross-referencing, I created a page to serve as an index to this subject called glucose catabolism.
Now we can add topics to this page. Rozzychan 20:07, 23 June 2006 (UTC)
replies: text: Wouldn't it be better to make a template? i think the page you have started could end up as a replicate of cellular respiration. David D. (Talk) 20:16, 23 June 2006 (UTC)
thread_title: Made a new index page [[Glucose_catabolism]]

message: Interested parties, please post your responses to my observations and compromise offer, and please remember to be civil and assume good faith in your peers. If you wish, simply add:
* Agree ~~~~ 
or if you disagree, please post constructive alternatives.
--Aguerriero (talk) 18:20, 27 June 2006 (UTC)
replies: text: By the way why are we in mediation, I didn't know there was really anything happening here? Obviously there is a lot of rewriting required, which is one reason i have not got stuck into this yet. But is there actually a real dispute here? I thought we were just beginning? David D. (Talk) 19:26, 27 June 2006 (UTC)
replies: text: Btarski requested mediation. --Arcadian 19:40, 27 June 2006 (UTC)
replies: text: Oh I see. The only reason I'm surprised is that its normally mayhem when a mediator gets brought in.  To date, i have just seen a bold move, that while not pretty, at least got the ball rolling on the fact that we need to get something done, i.e. rewite and reorganise. i do agree that the spin off articles were not articles, but i had assumed that they would be worked up to standard in due course.  I think there is room to have very specific details in those four spin off pages, although, they too need to be rewritten now that they are out of context.  This page will need to be rewritten to reflect the loss of the old material and highlight similarities and differences between the various transport chains. The challenge is to keep it simple while maintaining relevant links to encompase all the associated pages in wikipedia.  David D. (Talk) 20:24, 27 June 2006 (UTC)

text: It looks to me like this can be wrapped up quickly; I am just waiting for Btarski to respond. After the mediation, I will also make sure to communicate what other avenues of dispute resolution are available before going to mediation.  Thanks for your quick responses, everyone! --Aguerriero (talk) 20:33, 27 June 2006 (UTC)
thread_title: Responses

message: Since everyone who has showed an interest has agreed on a solution, I am closing the mediation case.  I suggest that you outline a plan for executing Btarski's proposal before carrying it out, perhaps as follows:
# Plan what content will end up on which page, based on the pre-split version.
# Revert Electron transport chain to the pre-split version.
# Perform the split into two articles as proposed.
# Arcadian blank the old split articles (now unused) and file requests for speedy deletion per G7.
Thank you for your cooperation and civility in this matter; carry on smartly. --Aguerriero (talk) 15:40, 29 June 2006 (UTC)
thread_title:  Closing 

message: In the interest of maintaining the momentum, the proposed split presented in full.  The proposed new articles are Electron transport chain and Photophosphorylation.  Their respective Tables of Contents will, hopefully, make more sense than the Table of the provisional 41 kilobyte article.
Some the material has been duplicated, and some of the material has been rearranged.  New material (which is intended to summarize the stuff removed from Part A and transferred to Part B, and to properly introduce the new Part B) has been added.  Nothing has been deleted.
I will leave it to your judgment whether to proceed with the split at this time.  Arcadian has the authority to make it official.
It has been a pleasure to work with you on this issue.  Thank you for all the time you took
Btarski 03:20, 1 July 2006 (UTC)
replies: text: Although I disagree that I have any special authority in this matter, in my personal opinion I do think that your work looks good, and I encourage you to move forward, and split the second half into Photophosphorylation. --Arcadian 04:38, 1 July 2006 (UTC)
thread_title: The proposed split

message: The first sentence in the article is "Electron transport chains (also called electron transfer chains) are biochemical reactions that produce ATP". However, if you read the article you probably won't understand how this electron transport chain results in ATP synthesis. This is why i added the coupling with oxidative phosphorylation section. I also added a hint about uncouplers to clarify that in certain cases the electron transport chain doesn't result in ATP synthesis. I read somewhere in this talk page a debate about ATP synthase: whether it is complex V or not. Well, though ATP synthase is responsible for oxidative phosphorylation, it is regarded by many textbooks as complex V. I revised Lehninger. The fact that ATP synthase is also called complex V is mentioned in pages 697 and 708. You can view page 78 in Lippincott's illustrated reviews in biochemistry here(requires a google account). Notice that figure 6.13 contains complex V which is ATP synthase.--Wedian 16:37, 12 July 2006 (UTC)
thread_title: Coupling with oxidative phosphorylation

message: I think the community would benefit if someone elaborated on the reverse electron flow briefly mentioned (perhaps creating a new page).
romunov 18:23, 12 January 2007 (UTC)
thread_title:  Expanding on a related topic 

message: "Electrons from these donors are passed through an electron transport chain to oxygen, which is reduced to water." was stated under the "Electron transport chains in mitochondria" section. What? So electrons are passed to oxygen, O, and is somehow reduced(made smaller) to water, H2O. This doesn't make sense to me how a molecule getting bigger, is considered reduced. I know it probably made sense if I knew the details, but it doesn't include any details on it. Thanks in advance. --24.27.141.96 (talk) 22:04, 11 December 2007 (UTC)
replies: text: Good point.  Would a wiki-link to redox be enough to clarify the usage of the word? David D. (Talk) 03:18, 14 December 2007 (UTC)
thread_title:  Oxygen is reduced to water? 

message: The article states in the Summary section at the end that "Electron transport chains are the source of energy for all known forms of life." While the ETC is a major component of most forms, I know that certain forms use only glycolysis as their energy source, anaerobic organisms in particular. While I would have normally just revise the offending material (and explain myself in the edit summary), I am merely an editor, with basic organic chemistry knowledge, who happened to stumble across this article. So I would like regular contributors to this article, who hopefully have a firmer grasp of organic chemistry than I do, to review the edit I made in case it too is incorrect. Typer525 Talk 04:16, 4 April 2008 (UTC)
replies: text: Inner cell membrane usually. Narayanese (talk) 20:30, 18 December 2008 (UTC)
replies: text: Auric light energy? I'm afraid you chanced upon the wrong entry for your comments. This article deals with the features and mechanisms of the electron transport chain that have been uncovered by scientific methods. Researchers all over the world (i.e., in the east and west) are engaged in scientific research, most of whom are not particularly phobic of "doctrines" (if perhaps sceptical of some of them). Auras along with fairies and pixies are fictitious objects or beings not to be confused with observable reality. So your promise to "enlighten" anyone about your theories smacks of sad irony, considering that the Enlightenment provided the spark that ignited modern scientific research. It helped do away with a great many superstitions and plain humbug, such as, for example, bloodletting, phlogiston, and witchcraft that have held back rational reasoning and progress for a long time. But, as your comment suggests, this doesn't stop some people trying to reset the clock. Malljaja (talk) 21:25, 29 April 2010 (UTC)
thread_title:  Source of energy for "all" life? 

message: It would be nice if some of our biologists here would add a section on how the ETC was discovered and by whom, when, etc.  I remember being in school not so terribly long ago and learning that the Krebs cycle generated the ATP for the body, but it appears the vast majority of ATP derives from the ETC.  A little history would not be unwelcome to the general reader, I think.  --64.66.85.99 (talk) 13:13, 27 October 2010 (UTC)
replies: text: Krebs cycle as such does not produce any ATP. However, it produces sufficient NADH that are used for the ATP synthesis. The one step of the reaction, succinate dehydrogenase, is however directly linked to the ETC. ATP production is also distinct, not really a part of ETC and is explained by the chemiosmotic theory. chami 19:24, 30 May 2012 (UTC)
replies: text: The Krebs cycle does produce one GTP directly. AlphaHelical (talk) 14:22, 11 May 2013 (UTC)
thread_title:  Discovery of ETC process? 

message: The article says
If protons flow back through the membrane, they enable mechanical work, such as rotating bacterial flagella. ATP synthase, an enzyme highly conserved among all domains of life, converts this mechanical work into chemical energy by producing ATP"
This seems confused.  It seems to imply that mechanical work, such as rotating flagella, is part of ordinary ATP synthesis using a proton gradient.  AlphaHelical (talk) 19:26, 20 April 2013 (UTC)
thread_title:  Mechanical work 

message: I'm removing this as the last paragraph of the article:
The coupling of thermodynamically favorable to thermodynamically unfavorable biochemical reactions by biological macromolecules is an example of an emergent property – a property that could not have been predicted, even given full knowledge of the primitive geochemical systems from which these macromolecules evolved.[original research?] It is an open question whether such emergent properties evolve only by chance, or whether they necessarily evolve in any large biogeochemical system, given the underlying laws of physics.[citation needed]
It's out of place, speculative, and uninformative.
173.25.54.191 (talk) 05:00, 30 June 2013 (UTC)
thread_title:  summary 

message: The current illustration (included here) indicates that the complex I reaction is NADH → NAD+ + H+. However, Biochemistry by Harvey and Ferrier says NADH + H+ → NAD+. Is there an error somewhere or am I misunderstanding things? —Bromskloss (talk) 22:14, 14 July 2013 (UTC)
replies: text: I thought about the same thing. Several other sources says that NADH + H+ → NAD+. I think 2 electrons are moved from NADH while the H+ from NADH and the free H+ goes into Coenzyme Q. 94.191.137.37 (talk) 17:48, 1 February 2023 (UTC)
thread_title:  Other source disagrees with "NADH → NAD<sup>+</sup> + H<sup>+</sup>". 

message: Substituted at 14:19, 29 April 2016 (UTC)
thread_title: Assessment comment

message: Currently there is an animated gif on the page that doesn't really fit the tone/style of the page, isn't really clear what information it conveys, and isn't encyclopedic. This file is also used exclusively on this page. I don't want to remove it without consulting the community. The file in question is 
Dietcoke3.14 (talk) 19:13, 15 August 2019 (UTC)
thread_title:  Out of place file 

message: Hi I am Toby. A 3rd year biochemistry undergraduate at Imperial College London. The page, as pointed out by teachers and professors, is a little confusing with link cycles and a lack of clarity. Also, the page lacks a common theme and some good images for a few sections. Overall it is good but I believe it could be improved in some areas. Outlined below are some proposed changes on the general layout, content and diagrams of the page.
==== Examples of potential changes to article. ====
1. More accessible lead.
The article is so widely used due to being a key topic throughout all levels of teaching. It is classed as a Level 5 vital article by wikipedia. This may be GCSE students to Professors. At the moment the lead section assumes a large amount of knowledge already. Perhaps this is okay for an undergrad but due to the importance of the topic at a lower level than this I believe the lead should be more accessible. One example of this is in the second sentence of the article. It may not be necessary to include information on how ATP stores energy with no further link about strained bonds. "This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds." A suitable change may involve moving this information to the ATP Synthase section and either linking to the adequate article to describe strained bonds and energy storage or addition of sufficient explanation for clarity.
2. Diagrams
Throughout the article there is a lack of consistent diagrams. One example of where a diagram could be produced for a clearer view of a process is the "Generalised electron transport chain in bacteria." Also, if there may be a new addition in these proposed edits that requires a diagram. One should be produced for this in accordance to others for consistency.
3. New additions
A few new additions to the page could be considered. A large topic only very briefly mentioned in the article is reverse electron flow in prokaryotic electron transport chains. This could have a new subsection under the bacterial heading.
4.Organisation
The article feels as if it could do with some cleaning. Some sentences in the lead article add don't add value and distract from key information. Also, in the later sections there is some ambiguity in what is stated, even if it is fundamentally correct. For example, "A small percentage of electrons do not complete the whole series and instead directly leak to oxygen, resulting in the formation of the free-radical superoxide, a highly reactive molecule that contributes to oxidative stress and has been implicated in a number of diseases and ageing." This statement is repeated in the lead. Either of these could be removed. In addition, the summary, at the end of the article, does not add value and likely would not be read by many. This could be removed as is not a general feature of good wikipedia articles. The need for an ending summary is negated by the lead.
If there are any reservations about any proposed changes please let me know and I'll gladly take them onboard. Tobyfensome (talk) 17:39, 16 April 2020 (UTC)
thread_title:  Proposed edits 

message: 1. More accessible lead.
The article is so widely used due to being a key topic throughout all levels of teaching. It is classed as a Level 5 vital article by wikipedia. This may be GCSE students to Professors. At the moment the lead section assumes a large amount of knowledge already. Perhaps this is okay for an undergrad but due to the importance of the topic at a lower level than this I believe the lead should be more accessible. One example of this is in the second sentence of the article. It may not be necessary to include information on how ATP stores energy with no further link about strained bonds. "This creates an electrochemical proton gradient that drives the synthesis of adenosine triphosphate (ATP), a molecule that stores energy chemically in the form of highly strained bonds." A suitable change may involve moving this information to the ATP Synthase section and either linking to the adequate article to describe strained bonds and energy storage or addition of sufficient explanation for clarity.
2. Diagrams
Throughout the article there is a lack of consistent diagrams. One example of where a diagram could be produced for a clearer view of a process is the "Generalised electron transport chain in bacteria." Also, if there may be a new addition in these proposed edits that requires a diagram. One should be produced for this in accordance to others for consistency.
3. New additions
A few new additions to the page could be considered. A large topic only very briefly mentioned in the article is reverse electron flow in prokaryotic electron transport chains. This could have a new subsection under the bacterial heading.
4.Organisation
The article feels as if it could do with some cleaning. Some sentences in the lead article add don't add value and distract from key information. Also, in the later sections there is some ambiguity in what is stated, even if it is fundamentally correct. For example, "A small percentage of electrons do not complete the whole series and instead directly leak to oxygen, resulting in the formation of the free-radical superoxide, a highly reactive molecule that contributes to oxidative stress and has been implicated in a number of diseases and ageing." This statement is repeated in the lead. Either of these could be removed. In addition, the summary, at the end of the article, does not add value and likely would not be read by many. This could be removed as is not a general feature of good wikipedia articles. The need for an ending summary is negated by the lead.
If there are any reservations about any proposed changes please let me know and I'll gladly take them onboard. Tobyfensome (talk) 17:39, 16 April 2020 (UTC)
thread_title:  Examples of potential changes to article. 

message: electron transport chain (ETC[1]) is a series of protein complexes and other molecules that transfer electrons from electron donors to electron acceptors via redox reactions (both reduction and oxidation occurring simultaneously) and couples this electron transfer with the transfer of protons (H+ ions) across a membrane. Many of the enzymes in the electron transport chain are membrane-bound 2409:4043:4E8A:71C2:D48C:5B18:7A4E:B671 (talk) 13:04, 27 March 2022 (UTC)
thread_title:  Olol 

message: Preparing for exam 119.155.199.146 (talk) 15:26, 16 December 2022 (UTC)
thread_title:  Biology