Talk:Glycolysis/Archive 1

other meaning
doesn't glycolysis also mean the cleavage of some molecular structure by the action of glycol (thus:ethanediol)? e.g. polyurethanes can be cleaved in this manner... 194.53.253.51 (talk) 14:24, 12 January 2010 (UTC)
 * Can you provide a reliable source using "glycolysis" that way? Yappy2bhere (talk) 15:02, 12 January 2010 (UTC)

Diagram
I have made the potentially controversial move of removing the glycolysis diagram from this page. My reasoning for this is that:
 * it is fairly unintelligible to even an expert reader
 * it is big, pixelated, and cramped in layout
 * it shows information which is widely duplicated in the rest of the document
 * the additional information in it (ie. cofactors and inhibitors) would fit better in an explanation of pathway flux explanation rather than a diagram

I have placed the code for the image on this page (but i did shrink it) to save the captions colour coding. This would take a long time to redo if the diagram is ever required again... Zephyris Talk 16:22, 3 November 2006 (UTC)
 * Many more edits later... Hopefully this article is now of significantly better quality, it has been restructured, rewritten, and loads of repeated points removed! Zephyris Talk 18:01, 3 November 2006 (UTC)

I'm not sure where to put comments, so I'll put it here. In the sequence of reactions section, the diagram for the reaction catalyzed by PFK-1 is wrong; it just shows G6P being converted to F6P when it should actually show F6P to F1,6P. ~a random observer, not Zephyris
 * Yup, my mistake, it has been corrected... - Zephyris Talk 19:40, 6 November 2006 (UTC)

I see another error; in the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase, the substrate should be glyceraldehyde-3-phosphate; however, the figure is of dihydroxyacetone phosphate. ~random observer, again
 * This appears to have been corrected, though I cant find the edit in the history where this has been done. - Zephyris Talk 12:13, 8 November 2006 (UTC)

The name of the substrate for the glyceraldehyde-3-phosphate reaction is correct; however, the diagram shown below that name is that of DHAP. It still appears to be wrong. I'm talking about the first reaction shown in the payoff phase. -random obs


 * *New diagram I am a bit confused by the new glycolysis diagram, who read a diagram start from the right hand-side, going down then up again to the left handside? uuuǝıɹ 13:13, 15 May 2013 (UTC)

oxidized?
This article states that during glycolysis, glucose is oxidized. It also states that flux through the pathway is greater in anaerobic conditions (i.e., in the absence of oxygen). Are these two statements contradictory? How can glucose be oxidized in the absence of oxygen?

At the end of glycolysis it can proceed to either the aerobic or aneorbic in eukaryotic cells (so lactic acid builds up in your muscles when a person is sprinting). -- Eean


 * Oxidation is, in the most general sense, loss of electrons or loss of hydrogen, not necessarily gain of oxygen. Oxygen is not required for glycolysis, merely oxidising power. This oxidising power does, however, need to be repaid somehow. In humans this is the oxygen debt associated breakdown of lactic acid.

Data dump: Key (reaction type & enzyme) δ G°' = ? * critical control point
 * 1) Chimical diagram of reactants
 * 2) Names of reactants

Glycolysis 1 ATP -> ADP + H+ 1)  . = radioactive label

2) å-D-G ––--->      å-D-G-6-P (phosphorylation, *Hexokinase) -4.0 kcal/mol  ATP -> ADP + H+

Glycolysis 2

1)  (P) is H2COPOsub>3 -2

H2COPO3-2 |___O         (P) O   CH2OH ./    \    -->   |/    \|         |\|___ /|  <--–––  \.__|/|               |             |

2) å-D-G-6-P ––--> Fructose-6-P (isomeration, phosphoglucoisomerase) +0.4 kcal/mol

Glycolysis 3 ATP -> ADP + H+ 1) (P) is H2COPO3+       (P)  O   CH2OH         (P)  O  (P)       |/     \|     -->      |/    \|        \.__ |/|     <--–––    \.__|/|         |                      |

+ ATP  + ADP + H+

2)   F-6-P   -->  F-1,6-BP (phoshorylation, phosphofrucoknse) -3.4 kcal/mol  ATP -> ADP + H+

Glycolysis 4 1)  (P)                |             (P)       HC.=O      C=O            |         |   __ |  –––  -->    C=O    + HCOH      |.__   <--–––  |         |      | __         H2C.OH     (P)      |       (P)

2) F-1,6-BP -->  DHAP + Gy-3-P (Isomerization, *aldolase) +5.7 kcal/mol

DHAP   Dihydroxyacetone Phosphate

Glycolysis 5 1) Lable is mixed in 2 species

(P)         HC.=O |           |       C=O   -->   HCOH |    <--    |     H2C.OH        (P) 98%         2%

2)   DHAP  -->  Gy-3-P (isomerization, triose-phosphate isomerase) +1.83 kcal/mol

Glycolysis 6 2(NAD -> NADH) 1) Double all molecules             HC.=O          O=C.-OPO3-2         |       -->     |        HCOH    <--––   HCOH         |               |        (P)             (P)

+ NAD + Pi    + NADH + H+

2) 2(Gy-3-P -->  1,3-BP-Gy) (dehydration, Gy-3-P dehydrogenase) +1.5 kcal/mol NAD + Pi -> NADH

Glycolysis 7 2(ADP -> ATP) 1) Double all molecules            O=C.-OPO3-2 C.OO-          |         |         HCOH  --> HCOH          |    <--  |            (P)       (P)

+ ADP    + ATP

2) 2(1,3-BP-Gy -->  3-PGy) (Phosphoryl Transfer, phosphoglycerate kinase) -4.5 kcal/mol  2(ADP -> ATP)

Glycolysis 8 1) Double all molecules               C.OO-       C.OO-          |      -->  |         HCOH   <--  (P)          |           |            (P)        H2COH

Note

2) 2(3-PGy -->  2-PGy) (Phosphoryl Shift, phosphoglyceromutase) +1.06 kcal/mol Note: 2-PGy's (P) has 1 fewer H than referance (P).

Glycolysis 9 ---> + 2H2O 1)  Double all molecules  (Note 1)           C.OO-        C.OO-        |  –   -->   |       (P)    <--   (P)        |           ||          H2COH         CH2

Note        + H2O

2) 2(2-P-Gy > phosphoenol Py) (Dehydration, enolase) 1st  molecule's (P) has 1 fewer H than referance (P). 2nd  molecule's (P) has 2 fewer H than normal (P)

Glycolysis 10 2(ADP -> ATP) 1)  Double all molecules  (Note 1)       C.OO-         C.OO-       |  –    -->   |      (P)     <--–   C=O      ||             |         CH2            CH3

+ ADP         + ATP

2) 2(PEP   -->  pyruvate) (Phosphoryl Transfer, )  ADP -> ATP -7.5 kcal/mol Note: 1st  molecule's (P) has 2 fewer H than normal (P)

TODO: Double check to make sure this is correct, try to translate into English, put into right justified table with text of article flowing on the left. --maveric149

NOTE: The pictures currently on the page do not depict the above reactions. See pyruvate: it currently has two ketone oxygens —Preceding unsigned comment added by 24.252.86.87 (talk) 01:34, 17 February 2010 (UTC)

Well spent
Not certain if the references to energy being 'well spent', etc during the energy investment phase are entirely appropriate. Seems to me to be a little unscientific. Stryer states that glycolysis is the sequence of reactions that converts glucose into pyruvate with the concommitant production of ATP. Based on this I don't think that Entner-Doudoroff can be considered a form of glycolysis. As far as I'm aware, glycolysis is Embden-Meyerhof. Could anyone confirm the differences between hexokinase and glucokinase? My information is hazy. I think maybe pathway section needs to be split - one for the pure reactions and then maybe a seperate one for the implications of the reactions. ie; that phoshorylation of glucose leads to instabliity that allows it to be split. I am unable to satisfactorily integrate the process and the reasons individual steps are carried out. Think this is on the way to being a really good article. All comments very very welcome. I'd like to hear your thoughts.Marc Isaacs

Welcome, and nice work at first glance. I have written an extensive article on glucokinase and fleshed out the article on hexokinase, so I would value your opinion as to whether they adequately answer your question about the differences. Many of our articles on carbohydrate metabolism could be improved, or at least made more physiological so there is some context for the reactions. alteripse 11:56, 1 Jun 2005 (UTC)

Hi. I'll look through those articles when I have a bit more time to study them properly. You're right - the glucokinase one certainly is extensive :o). I think what you say about making this article more physiological is a very good point. With this in mind, perhaps there is potential for a section on regulation of the process? This could allow for a lot of detail to be removed from the pathway section, making that a bit more streamlined. What do you think? Marc Isaacs 14:33, 1 Jun 2005 (UTC)

It seems that glycolysis is indeed sometimes used to include ED. See, for exampe, these articles. I'm not sure why you think ED is inconsistent with Stryer's definition (is it because he says "the sequence of reactions" rather than "any sequence of reactions"? since there isn't just one, his definition is ambiguous, at best), but I wouldn't base this call on a definition in an introductory text. With that said, I note that people sometimes clearly discuss glycolysis on the one hand and ED on the other. Josh Cherry 15:25, 4 Jun 2005 (UTC) Josh, could you please provide PMID rather than link like this, as I don't get anything when I click on your link except the NLM page with no query. alteripse 15:31, 4 Jun 2005 (UTC)
 * Oops, I messed up the link. It's fixed now. Josh Cherry 16:08, 4 Jun 2005 (UTC)

Layman's English?
Hi, is there any chance of anybody sticking in a sentence or two about what this is in layman's terms. As somebody who takes part in sport I was interested in anaerobic functions and what it means for the body in broad terms, but have very little knowledge of either Biology or Chemistry (I'm an engineer by trade).

Is this what you had it mind at the beginning? If you like it, sign up with us and write about some engineering topics. alteripse 00:28, 24 July 2005 (UTC)

Should this be merged with "Cellular Respiration?"
Reading this article and Cellular Respiration, it appears that they duplicate a lot of information. Should they be merged?


 * No, the reason they share a lot is becuase of the classical view for the purpose of the reactions of Glycolysis - convertion of Glc to Pyr with the formation of ATP. Instead, Glycolysis should be looked at as a chemical channel that conects the pool of the carbohydrates with the pools of the aminoacids and the lipids, a role which has the involvement in the energy production as being a small part. -- BorisTM


 * I agree. Keep separate. Expansion is possible. alteripse 15:01, 17 October 2005 (UTC)


 * Very much no, as BorisTM says. Zephyris Talk 13:39, 3 November 2006 (UTC)

NADH to NADPH
Hi Tito400, I understand that this can happen. I do not understand the relevance to glycolysis. Why should this be mentioned in this article? The only thing i can think of is that it is another way to recycle the NADH to NAD+ but how significant is that reaction during hypoxia compared to the pyruvate to lactate reaction? David D. (Talk) 18:00, 22 November 2005 (UTC)

Hi Daycd. The original statement was "Although fermentation does not produce much energy, it is critical for an anaerobic or hypoxic cell since it regenerates NAD+ that is required for glycolysis to proceed" However, that is a tautological clause unless we specify why it is important to have a plentiful pool of NAD/NADH despite the very low efficiency of glycolysis in terms of ATP production. Back to you David! --Tito4000 03:32, 23 November 2005 (UTC)

I see your reasoning now, but that is not the rationale I am using. You're right we need to spell it out. The reason the NAD+ is important is for reaction 6 in glycolysis: (cut and paste from above)

Glycolysis 6

HC=O          O=C-O~PO32- |      -->     |        HC-OH   <--––   HC-OH |              |       H2C-O-PO32-      H2C-O-PO32-

+ NAD+ + Pi    + NADH + H+

(Gy-3-P NAD+ + Pi -->  1,3-BP-Gy + NADH)

(dehydration, Gy-3-P dehydrogenase)

If glycolysis runs fast in anaerobic condition one glucose will leave 2 pyruvate, 2ATP and 2NADH and this is great to get that ATP. The caveat is that if all NAD is in the reduced NADH form (the cellular pool is small enough that is does not take long for this to happen) then the oxidation reaction above cannot proceed since there is no NAD+ substrate. Obviously in aerobic respiration this is not an issue since the NADH is quickly oxidised by reactions in the mitochondria. The solution that the anaerobic organisms use is to cycle the NADH back to NAD+ by reducing the pyruvate to one of many different feremntation products. For example the reaction for pyruvate to lactate:

Pyruvate + NADH --> Lactate + NAD+

So in summary, without reducing the pyruvate to recycle the NADH to NAD+ glycolysis would grind to a halt due to no substrate for reaction six.

While I agree that the NADH can be reduced to by NADP+, in practise this would never work in a cell to keep fermentation going since the pool of NADP+ would soon run out and son on. Does this make sense? David D. (Talk) 04:01, 23 November 2005 (UTC)

Hi Daycd. Well, I believe that in practice the exercise explained above would actually work since the triose-P intermediates would end up elsewhere as building blocks rather than in the pyruvate/lactate sink. Thus, the resulting net NADH can be available to be converted to NADPH, which is the preferred pyridine cofactor in biosynthetic processes. This is in fact one of the real functions of anaerobic glycolysis, namely to provide carbon building blocks and reducing equivalents to biosynthetic pathways. At any rate, you've got my idea. Why don't I leave it up to you to edit this in a concise and digestible form. --Tito4000 22:48, 23 November 2005 (UTC)


 * Tito4000, it seems to me that you are missing a lot of things. The direction in which a revirsible reaction will preceed is determined by two factors - the nature of the reactants/substrates and their concentrations. Let's ignore the first factor and see how the second one affects the direction in a simple oxido-redox with the initial relative concentrations of the reactants being [1]:

A(red)[1] + B(ox)[1] <---> A(ox)[1] + B(red)[1]

Now if B(ox) concentration is increased 10 times - [10] - the reaction is expected to proceed to the right, the oposite will hapen if B(red) is increased 10 times. Well normally [NAD+]/[NADH] ratio inside the cell is 700, while [NADP+]/[NADPH] is 0.014 or if you turn it around [NADPH]/[NADP+]=60!!! So if the cell wants to oxidize a substrate (A) it will use the NAD+/NADH system

A(red)[1] + NAD+(ox)[700] <---> A(ox)[1] + NADH(red)[1]

for the reduction it uses NADPH/NADP+

A(red)[1] + NADP+(ox)[1] <---> A(ox)[1] + NADPH(red)[60]

Now if we put these two cofactors ever cross pathways in a reaction that you say is more likely to happend during anaerobic glycolysis, tell me in which way it is going to proceed

NADH(red)[1] + NADP+(ox)[1] <-?-> NAD+(ox)[700] + NADPH(red)[60]

apparently it will result in NAD+ oxidizing NADPH. Yes, NADPH is used in the biosynthetic pathways but these pathways need much more the energy of ATP and other energy rich compounds than they need reducing equivalents. Even if there is a type of cell that uses this reaction a lot (you might as well provide us with some sources), it is more an exeption than a rule, so, at least for me LDH still runs the show. Boris 18:36, 24 November 2005 (UTC)

Hi Boris. Well, you're right, I miss a lot of things; nevertheless, I don't claim otherwise. However, don't you miss the point that all I'm stating is that glycolysis doesn't necessarily go always straight down to pyruvate; sometimes, it does stop on the way deriving glucose carbons to necessary intermediates, and the resulting reducing equivalents become very handy for biosynthetic endeavors. Obviously, for biosynthesis to proceed swiftly a lot of ATP is needed too, but I don't see where I stated that this ATP must also come from glycolysis. On the other hand, I like your theoretical disquisition on enzyme thermodynamics although it's totally irrelevant to my point. In spite of your heavy-handedly having reverted my edits, I will not revert yours. I'll leave this point to people like yourself who don't miss anything. --Tito4000 14:36, 25 November 2005 (UTC)


 * Hi Tito, Your point that glycolysis, and TCA cycle for that matter, is a source of metabolic intermediates is a good one. Looking through the article it is a point that is missing. However, this is all about the relative importance of flux through different pathways.  Obviously intermediates for anabolism are a critical role for gylcolysis but it is relatively minor compared to its role in producing ATP in an anaerobic environment. Remember that in anaerobic conditions glycolysis is the ONLY source of ATP. Since you say "I don't see where I stated that this ATP must also come from glycolysis" you are implying the ATP might come from another source.  Effectively this is a bioenergetic shell game, since eventually, for an anaerobe, all ATP must come from glycolysis.
 * Unfortunatley I don't have any good examples at hand, but lets assume that the anabolic reactions in an anaerobic cell requires 2ATP for every NADPH (this is probably a good approximation). Each glucose that is metabolised to pyruvate will yield 2ATP and 2NADH. In that scenario the NADH can never be fully recylced as the ATP will be limiting (as only 1NADP+ is made available for every 2ATP actually used).  Since the NADH will keep building up the cells the supply of NAD+ will quickly be depleted and death will follow.  Consequently, for survivial, there must be a way to make ATP with out using anabolic reactions.  The solution is the pyruvate to lactate reaction as we have been discussing here.  Without it the cells would die due to the inhibition of glycolysis by low levels of NAD+.  It is definitely the only critical reaction with regard to the recycling of NAD+ if not the only possible wat to recycle the NAD+. David D. (Talk) 17:49, 25 November 2005 (UTC)

Hi David. To say that a cell is living under strict anaerobic conditions doesn't imply that the glycolytic pathway is being used glucose to lactate (or alcohol) ALL the time. Let's not be fooled by stoichiometric analysis; that's mostly theory. My point is precisely that in reality the glycolytic flux -part of the time- must be devoted to deriving carbon units and reducing equivalents essential for biosynthesis elsewhere in the cell. When this happens the resulting NADH is used to increase the necessary NADPH pool. That's all. No thermodynamics or quantum mechanics I believe is needed to explain this. --Tito4000 15:47, 26 November 2005 (UTC)


 * I agree with the "part of the time" aspect of glycolytic flux. This defintely needs to be incorporated into the article. The same is true for the TCA cycle metabolites. Also the fact that glucose is not the only entry point. fructose, galactose and mannose not to mention that triose molecules can enter at the half way point.  It's also worth noting that the major control of the pathway is downstream of the entry point into the pathway for all the hexoses (phosphofructokinase).  I agree with your interpretation that glycolysis is required to provide reducing equivalents for anabolic reactions.  This needs to be clarified in the article too.
 * So where do i disagree? I diagree that the provision of the reducing equivalents ALONE to anabolic reactions is enough maintain flux through the glycolytic pathway (by recycling NADH to NAD+). ONLY the pyruvate to lactate or equivalent can maintain the NAD+ levels to allow the pathway to function.  While the others certainly help, none are critical for this function. Pyruvate to lactate is critical which is why it should be the only one mentioned with regard to maintaining the levels of NAD+.
 * In summary we need a new section to introduce the concept that metabolites and reducing power is syphoned off to other metabolic pathways, as well as glucose is not the only entry point. A good example of the latter might be 'what happens when you eat sugar (sucrose)'. It gets broken down into glucose and fructose.  Glucose enters via hexokinase as glucose-6-phosphate, while the fructose enter, also via hexokinase, as fructose-6-phosphate one step further down the  pathway. We also need a section on regulation of the pathway that discuss negative feedback on flux due to high levels of ATP, fructose-2,6-bisphosphate or citrate. David D. (Talk) 18:01, 26 November 2005 (UTC)

Hi David. I agree with you. Let's do it. Why don't we let you start and I'll chip in along the way. --Tito4000 15:09, 27 November 2005 (UTC)

enolase
you have put this is a hydrolase enzyme however i believe this enzyme, 4.2.1.11 is a lyase enzyme

NADP+/NADPH
"From an anabolic metabolism perspective, the NADH has a role to drive synthetic reactions, doing so by directly or indirectly reducing the pool of NADP+ in the cell to NADPH, which is another important reducing agent for biosynthetic pathways in a cell." Is this really correct? I thought the reduction NADP+->NADPH took place in the pentose phosphate pathway, which does not involve NAD+/NADH.

The pentose phosphate pathway, together with transaldolase, transketolase and part of the glyconeogenesis pathway, can catalyze the reaction glucose-6-phosphate + 12 NADP+ + 7H2O -> 6CO2 + 12NADPH + 12H+ + inorganic phosphate, i.e a complete oxidation of glucose producing NADPH from NADP+ (Jeremy M. Berg, John L. Tymoczko, Lubert Stryer, Biochemistry, 5th ed), so it would be strange if there were a pathway that made NADH + NADP+ -> NAD+ + NADPH. Narayanese 11:26, 26 April 2006 (UTC)

Diagram, nice - simpler version?
That diagram whilst impressive is so complicated its not even any good to a Biochemist. It gives more information than a wikipedian needs, can we consider replacing it with a simpler version?

Well, here are examples of much simpler diagrams: staff.jccc.net/PDECELL/cellresp/glycolysis.html  http://web.indstate.edu/thcme/mwking/glycolysis.html#reactions Or maybe more of a flow chart type of thing would do? -unrgsrd

COMPARATIVE BIOCHEM OF GLYCOLYSIS
This is an incomplete treatment of glycolysis. A comparative biochem section should also be included. Plant glycolysis differs in some very key ways, namely in regulation and the some pyrophosphate dependent 'bypasses'. It would be nice if someone added this. —Preceding unsigned comment added by 69.157.48.127 (talk • contribs) and might be CBSB (talk · contribs)
 * I removed the following paragraph you inserted for now:
 * In plants ATP-phosphofructokinase is not activated by fructose-2,6-bisphosphate, but PPi-phosphofructokinase is. Fructose-2,6-bisphosphate synthesis and degradation is regulated by the levels of triose phosphates and inorganic phosphate, where inorganic phosphate promotes synthesis and inhibits degradation and triose phosphates inhibit synthesis. This mechanism prevents the plant from synthesizing sucrose when there are too few triose phosphates.  Low triose phosphate concentration leads to high fructose-2,6-bisphosphate concentration and this decreases the activity of fructose-1,6-bisphosphat e ase and leads to an increase in the flux through glycolysis through activation of PFP.
 * First, i assume that you are referring to the enzyme not the substrate (see bolded addition)? This is the first mention of this enzyme in the article and is a little out of left field in this context. Second the logic seems off when you state that: "This mechanism prevents the plant from synthesizing sucrose when there are too few triose phosphates". The prevalent flux through glycolysis is not because PFP is active but because the levels of triose are low. There would be nothing stopping a reverse of glycolysis as PFP is reversible (as opposed to PFK1).
 * There needs to be more discussion about the tole of PFP over PFK. Is the reverability of the enzyme important for its function? What are the differences in activity  between the PFP and the PFK1 in the cytosol?
 * At present, this paragraph does not have the context required to be useful. PFP is a reversible alternative to the combination of PFK1 and F16BPase in animals. But plants still have the latter two enzymes. All this needs to be stated somewhere. If comparative analysis is really the goal here then i would suggest it is also important to discuss the difference between the different isozymes in the cytosol and the choroplast. It should also be mentioned that PFP is cytosolic.
 * In swummary this is quite complex biochemistry you are trying to introduce into this article and I'm not even sure the real roles of this enzyme are fully understood. Probably a brief mention that it exists is enough for this article. Lastly, I think we might be straying from the point of this article. Much of this discussion is more appropriate in the gluconeogenesis article. Or we should create a companion article that discusses the regulation of flux using these two pathways. David D. (Talk) 17:21, 27 September 2006 (UTC)

SOME HELP PLEASE---

I need some help. I am currently doing a project on Glycolysis and the Citric Acid Cycle. Can anyone tell me where Glycolysis and the Citric acid cycle take place, and why?

In Praise of Glycolysis

 * The tune of The British Grenadiers ist used in the The Biochemists' Songbook's song In Praise of Glycolysis Text mp3 -- 172.158.36.154 12:41, 11 December 2006 (UTC)

Realtion to LDH and normal physiological breakdown of RBC hemolysis relation to glycolytic cycle?
wondering if / where LDH fits in to the glycolytic cycle in relation to hemolysis and normal physiological function. —The preceding unsigned comment was added by 207.151.251.28 (talk) 22:30, 12 February 2007 (UTC).



Printable Glycolysis Pathway
I know that current view is to use the line drawings of molecules in pathways, but I find that when teaching glycolysis to introductory students, it is important to include every atom, so I made an old-fashioned Glycolysis pathway diagram from scratch.

I am going to add it to the article as a printable glycolysis pathway page as the article itself is large and detailed to be a quick reference. Rozzychan 20:19, 25 February 2007 (UTC)
 * As I said on the metabolic pathways wikiproject; good job! :) - Zephyris Talk 01:15, 26 February 2007 (UTC)

In PEP and Pyruvate he H should be removed from the C2 carbons 212.201.44.249 14:18, 24 March 2007 (UTC)

Corrected said very nice picture. Let me know if I didn't do something right.  N i g h t F a l c o n 9 0 9  0 9 '  T a l k  21:17, 12 April 2007 (UTC)
 * hi, am not sure but doesnt the glycolytic pathway end at lactic acid production or does it just stop at pyruvate???Vik4989 06:45, 5 August 2007 (UTC)
 * Glycolysis goes as far as pyruvate, lactic acid production is fermentation. Jack the Stripper (talk) 14:09, 29 November 2007 (UTC)

energy quotient
wats the gross and net enrgy(in cals and no. of ATPs) produced?? and exactly in which steps??Vik4989 06:40, 5 August 2007 (UTC)

2 ATP are produced with each run of glycolysis (Net) 4 ATP are produced overall, but 2 are invested in early steps —Preceding unsigned comment added by 74.118.177.189 (talk) 02:38, 10 March 2011 (UTC)

Simple Diagram
Any reason to put in a simple diagram, summarising the glycolysis process? To me, all the diagrams seem to go into way too much detail what the average person would need.

Oh and thanks for taking out that super-duperly complicated one... that blew my head off! - Massau 09:55, 20 October 2007 (UTC)

Can someone renumber the bar chart in the "Regulation" section that illustrates the changes in free energy. It only numbers the bars 1 through 9 but there are actually 10 bars, representing the 10 steps, on the graph. It appears that the problem lies in the excessive spacing of numbers 6-9, which are placed over the last four bars that need to instead be numbered 6-10. —Preceding unsigned comment added by 216.185.233.136 (talk) 17:00, 14 February 2009 (UTC)

Hexokinase: Eukaryocentric!
As currently written, this article implies that the phosphorylation of glucose in glycolysis is invariably carried out by hexokinase (or glucokinase). In fact, many prokaryotes use the phosphotransferase (PTS) system, transferring a phosphate from PEP as the glucose is transported into the cell. This really should be acknowledged, but I am not an expert on this. There is a very poorly written Wikipedia article on phosphotransferases that makes mention of this, to which I would hesitate to link anything. I would hope to see this cleared up by a knowledgeable individual. MicroProf 04:03, 22 October 2007 (UTC)
 * You seem to under estimate your status as an "expert". You seem to know about it, which is more than most. I think the eucaryocentric slant is inevitable given that glycolysis is a core part curriculum but almost always present from the perspective of eucaryotes. If you have more insights to broaden the perspective you should add them. David D. (Talk) 07:39, 22 October 2007 (UTC)

Redirect
Can someone put a redirect for this page from "anaerobic respiration"? Prottos007 (talk) 00:01, 16 December 2007 (UTC)
 * No one in their right biological mind will, since they're not the same. Anaerobic respiration continues from glycolysis but differs from regular respiration in that it doesn't use O2 as an electron acceptor. Jack the Stripper (talk) 00:35, 11 January 2008 (UTC)

ADP - How about defining, explaining and hyperlinking it?
ADP - How about defining it, explaining what it is and hyperlinking it?

ATP, NADP, NADPH are explained, and hyperlinked  but not ADP.

We novice laymen need some help here!

Otherwise, good article and very pertinent, especially today! Rrrrprrrr (talk) 19:27, 9 February 2008 (UTC)
 * Abbreviation for adenosine diphosphate (as opposed to ATP, adenosine triphosphate. It just has a phosphate group removed). I'll edit the article. Jack the Stripper (talk) 14:29, 8 April 2008 (UTC)
 * Someone beat me to it. Jack the Stripper (talk) 14:32, 8 April 2008 (UTC)

Dutch link
When going to the Dutch version of this site ("Nederlands") you go to Pipo de Clown (a dutch tv show which has absolutely nothing to do with glycolysis). I don't know how to change it, so please change it. thank you. User:philip1201 19:09, 16 March 2008

2NAD+ -> 2NADH + 2H+ and 2ADP -> 2ATP intermediate processes
Something is wrong with the formatting of an image. By using, it makes the input display two intermediate reactions that cancel out each other (see [corrected] title above), and that would make the net change of molecules appear to be zero, i.e. no NADH, H+ or ATP is produced in two respective reactions concerned. Can someone else fix this? (My biology exam is in 30 minutes, so I can't trouble myself looking for the correct image and format at this time, sorry) Vic 226說 16:47, 10 October 2008 (UTC)
 * In what way should it be fixed? The arrows made larger? David D. (Talk) 18:25, 10 October 2008 (UTC)
 * I don't know why you would think that as the size of arrows is just simply unrelated, but perhaps I did not make myself clear in a hurry. For the overall glycolysis cycle, a net total of two NADH + H+ and two ATP should be produced. I don't know about whether the pathways which involve the two sets of molecules above are reversible, but by using the image/template above, it's instead showing that 1) both NADH + H+ and NAD+ are being produced at the same rate; 2) both ATP and ADP are being produced at the same rate. Which would imply that there would be no net product for the two metabolic pathways concerned. I'm thinking of using the template with |Image:Biochem reaction arrow foward YYNN horiz med while having "2 ATP" and "2 NADH + H+" (2 to indicate that there are two being produced) would better clarify the pathways, although I'll have to look into the template format to see how it works. Vic 226說 19:00, 15 October 2008 (UTC)


 * It is a reversible reaction. The overall direction depends on the concentration of the subtrates/products with respect to the equilibrium of the reaction. As the environment in a cell changes then the overall reaction can go either way. David D. (Talk) 19:14, 15 October 2008 (UTC)

Above discussion is continuing at Template talk:Glycolysis

Abbreviations
At the end of this article is a table of "Alternative nomenclature", shown below.

I propose to replace the abbreviations in this article with the compound names, and remove the table. Some biochemistry textbooks use abbreviations; some don't. I think the article would be easier to read if the names were spelled out. What do you think? Christopher King (talk) 20:43, 14 December 2008 (UTC)

The entry of galactose and fructose to the glycolysis pathway
Hey all. I'm thinking of adding a section in the article on how galactose and fructose undergo glycolysis and the reaction relevant to those processes. Any objections? Shiningheart (talk) 13:55, 15 December 2009 (UTC)
 * You mean adding a bit about where those sugars enter the pathway? Go for it. --Quadalpha (talk) 03:42, 14 January 2010 (UTC)

Top diagram
Can someone change the "bi-" in things like "biphosphate" to "bis-"? That is the correct form, right? Plus it would be consistent with the text. --Quadalpha (talk) 03:42, 14 January 2010 (UTC)

Glycolysis Overview Picture
In the first glycolysis overview picture I think the starting molecule of glucose may be incorrect. It only contains 11 hydrogen in the initial picture when it should be 12 (and so on through the diagram). Jinxx0r (talk) 05:37, 9 March 2010 (UTC)

Evidence that PFK is ratelimiting?
I noticed that the section on phosphofructokinase states that "This is also the rate limiting step." What does this statement mean and what evidence is there to support it? 18:25, 17 May 2010 (UTC) —Preceding unsigned comment added by Hsauro (talk • contribs)


 * The reason it's a rate limiting step is because the enzyme requires ATP as a co-substrate. It is also inhibited by high concentrations of ATP, Hydrogen Ions and Citrate molecules.  I'll try rewording the article.  Beamoflaser (talk) 23:35, 25 October 2010 (UTC)

Pyruvate or Pyruvic Acid ?
I have a textbook which states that glycolysis actually forms pyruvic acid, which is ionized into pyruvate due to the blood's pH. In fact, the whole process is presenting acidic intermediates: for example, 3-phosphoglyceric acid rather than 3-phosphoglycerate. Does the glycolysis actually result in molecules with carboxylic acid groups ? If so, then their ionization into salts would mean liberation of H+, hence participating in / causing acidosis. 76.10.161.207 (talk) 22:44, 16 September 2010 (UTC)

Clarification of PFK-1 step
The article states: Because the reaction catalyzed by Phosphofructokinase 1 (PFK-1) is not energetically very favorable, it is, in essence, irreversible, and a different pathway must be used to do the reverse conversion during gluconeogenesis. That does not make a whole lot of sense from a chemical point of view. Rather, chemical reactions that are not very favorable energetically establish an equilibrium and don't proceed irreversibly. I think what was meant to be said was that because the reaction is coupled with ATP hydrolysis, an energetically favorable step, it is in essence irreversible.

Or maybe I have been reading too much about metabolism for studies and am just nit-picking. Anyways, I made the change. Jimhsu77479 (talk) 00:08, 10 November 2010 (UTC)

Sugar biasedness
Why do we only describe the process of glucose into pyruvate? If fructose can also turn into pyruvate by entering the pathway in later steps, why don't we call that frycolysis? Dictabeard (talk) 23:37, 5 March 2011 (UTC)

Embden Meyerhof Parnas
In the wiki article I read the following: "The most common type of glycolysis is the Embden-Meyerhof pathway (EMP pathway).." This is incorrect since the abbreviation EMP stands for Embden-Meyerhof-Parnas (ref: BH Kim, GM Gadd,Bacterial Physiology and Metabolism, 3rd edition, 2011). It is also silly to abbreviate Embden-Meyerhof pathway to EMP, and call it EMP pathway, thus suggesting it is called Embden-Meyerhof pathway pathway. Also in the wiki article about Jakub Karöl Parnas, the pathway is stated correct as Embden-Meyerhof-Parnas. http://en.wikipedia.org/wiki/Jakub_Karol_Parnas Cuculus (talk) 12:00 10 October 2012 (GMT)
 * Thanks Cuculus. You're most welcome to make the correction.  You don't need permission or consensus to correct errors, especially when you have a reference. Adrian J. Hunter(talk•contribs) 04:09, 11 October 2012 (UTC)

History
Who discovered it? Should be mentioned in the article. — Preceding unsigned comment added by Mindravel (talk • contribs) 05:22, 23 April 2013 (UTC)

Diagrams
Previously the article included these diagrams: I've replaced them with File:Glycolysis metabolic pathway 3.svg which I hope is both an informative lead, as well as a simple summary. I plan to use the image annotation to insert wikilinked names (as in this example)
 * File:Glycolysis2.svg as the lead
 * File:Glycolysis.jpg as a summary in the first overview section

We currently also include the possibly redundant: Although the massive png image is more thorough, perhaps it is a bit much for the glycolysis article and could be moved to metabolic network or metabolic pathway?
 * File:Metabolism_of_common_monosaccharides,_and_related_reactions.png massive pathway (hidden)
 * Template:GlycolysisGluconeogenesis WP534 interactive map.

Let me know your thoughts. T.Shafee(Evo&#65120;Evo)talk 11:14, 27 March 2015 (UTC)

Contrary
...to the closing statement of the lede, the word glycolysis does not refer to the Entner-Doudoroff pathway, or vice versa. The two terms are viewed as and used distinctly, and if a source is found saying otherwise, it does not reflect mainstream scholarly and research usage. Le Prof 71.201.62.200 (talk) 06:27, 4 August 2015 (UTC)