Talk:Cell metabolism

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Here are some tasks you can do:

    From User:Lexor/Temp/Cell (NCBI), to be merged into article, or into cellular respiration --Lexor|Talk 13:25, 19 Sep 2004 (UTC)

    Let's break down each of these steps so that you can better understand how food and nutrients are turned into energy packets and water. Some of the best energy-supplying foods that we eat contain complex sugars. These complex sugars can be broken down into a less chemically complex sugar molecule called glucose. Glucose can then enter the cell through special molecules found in the membrane, called glucose transporters. Once inside the cell, glucose is broken down to make adenosine triphosphate (ATP), a form of energy, via two different pathways.

    The first pathway, glycolysis, requires no oxygen and is referred to as anaerobic metabolism. Glycolysis occurs in the cytoplasm outside the mitochondria. During glycolysis, glucose is broken down into a molecule called pyruvate. Each reaction is designed to produce some hydrogen ions that can then be used to make energy packets (ATP). However, only four ATP molecules can be made from one molecule of glucose in this pathway. In prokaryotes, glycolysis is the only method used for converting energy.

    The second pathway, called the Kreb's cycle, or the citric acid cycle, occurs inside the mitochondria and is capable of generating enough ATP to run all the cell functions. Once again, the cycle begins with a glucose molecule, which during the process of glycolysis is stripped of some of its hydrogen atoms, transforming the glucose into two molecules of pyruvic acid. Next, pyruvic acid is altered by the removal of a carbon and two oxygens, which go on to form carbon dioxide. When the carbon dioxide is removed, energy is given off, and a molecule called NAD+ is converted into the higher energy form, NADH. Another molecule, coenzyme A (CoA), then attaches to the remaining acetyl unit, forming acetyl CoA.

    Acetyl CoA enters the Kreb's cycle by joining to a four-carbon molecule called oxaloacetate. Once the two molecules are joined, they make a six-carbon molecule called citric acid. Citric acid is then broken down and modified in a stepwise fashion. As this happens, hydrogen ions and carbon molecules are released. The carbon molecules are used to make more carbon dioxide. The hydrogen ions are picked up by NAD and another molecule called flavin-adenine dinucleotide (FAD). Eventually, the process produces the four-carbon oxaloacetate again, ending up where it started off. All in all, the Kreb's cycle is capable of generating from 24 to 28 ATP molecules from one molecule of glucose converted to pyruvate. Therefore, it is easy to see how much more energy we can get from a molecule of glucose if our mitochondria are working properly and if we have oxygen.

    This article contains material from the Science Primer published by the NCBI, which, as a US government publication, is in the public domain.


    Moved from discussion at previous article "Catabolism":

    --MattDal 05:09, 3 Sep 2004 (UTC)The section on th empirical formula of carbohydrates is incorrect. This was once believed to be true but has since shown to be incorrect. The formula is at best a general rule of thumb

    [edit] Subpages

    Seems to me that what we have are three (almost) definition pages: cell metabolism, anabolism, and catabolism. These should be combined since each now is pretty much limited by the fact that all the details are being developed in separate artticles (which I think is a good idea). If this article could serve as an introduction to cell metabolism and a branching to the details developed from here, the reader would not need to wander around so much. I'll try to develop to illustrate. Anybody see problems with this approach? - Marshman 23:35, 28 Oct 2004 (UTC)

    Marshman, I'm inclined to your approach, splitting up articles too much is as bad as over-agglomeration. Since the catabolism and anabolism are currently fairly short, it makes sense develop them as sections within this article and then split them up if they get too large. Otherwise we have too much balkanization of the articles (as we have now) and readers have to hunt around several articles to get a complete picture. Compare this to the cell (biology) article which has the material in place, but plenty of Main article: links to specialized article. Basically we should use good summary style. --Lexor|Talk 05:54, Nov 16, 2004 (UTC)

    Moved in from User talk:Marshman about Metabolism:

    I thought that we could start a discussion on the Talk page about this, so followups should probably go there. --Lexor|Talk 05:58, Nov 16, 2004 (UTC)

    Did you mean Cell metabolism? My comment is at Talk:Cell metabolism. Metabolism is pretty much a disambiguation page. I went ahead and expanded Cell metabolism by bringing in the Anabolism and Catabolism articles; in the latter case, I left the detail behind, but in the former case there was no detail to leave and I would suggest that article become a redirect for now. - Marshman 17:12, 16 Nov 2004 (UTC)
    Er, yes, sorry about that, I did mean cell metabolism. --Lexor|Talk 10:39, Nov 17, 2004 (UTC)
    I'm confused. Bensaccount moved all the "stubs" out of cell metabolism, but Lexor put them in Catabolism, reversing the work I did previously. All we are doing is creating a bunch of stubs. Once an article says "see Main Article at ...." it is forever a stub unless similar short pieces can be logically combined into a master article (here "Cell metrabolism"). So lets have just one or no stub and not 3 or 4 - Marshman 18:18, 16 Nov 2004 (UTC)
    Agreed. --Lexor|Talk 10:39, Nov 17, 2004 (UTC)

    Haven't you ever noticed that every subject has subtopics? Once a subtopic has its own page it no longer needs to have the same stuff on the main topic page. A reference to the subtopic's page is better.

    • Don't make the reader sort through extraneous material.
    • It is bad to have two pages saying the same thing.
    • Eventually someone will change one of the pages and there will now be two pages with slightly different versions of the same thing. This can be very irritating for a reader. Bensaccount 02:24, 17 Nov 2004 (UTC)

    PS. Anabolism and catabolism do deserve their own articles and if you want to stop this page from being a stub -- try and add more subtopics (there are a LOT more than just two).Bensaccount

    It is up to the person doing the splitting into multiple articles to justify the action by providing the material to flesh them out beyond stubs. Otherwise, it is goiod housekeeping to consolidate stubs down into as few articles as necessary to encourage otherrs to add material. I suggest you are using a backwards approach to keeping things tidy around here. - Marshman
    I disagree that they need their own articles yet. Anabolism is less than a para, and catabolism is only about 4-5 paras, they need to be discussed in conjunction, if and when they increase in length, then that is the right time to split them out, but they are just too short currently. --Lexor|Talk 10:39, Nov 17, 2004 (UTC)

    btw, the rest of your changes to this page were good.

    I agree with the idea of having a main page and specialized pages in general, but the summaries that are left in the page should be of a decent length so that an article can be read as a standalone work, only diving into the specific page when more detailed work is required. The sections on anabolism and catabolism are not long enough (yet) to warrant separate pages. If a section becomes long enough, then, yes, I agree with you, we need specialized pages, but since anabolism and catabolism are so intertwined with each other and are currently so short, they really need to be discussed at length in this page.
    To be concrete, examples of what I consider the "right" amount of balance between main articles on major topics (think Britannica Macropedia) and specialized articles (think Britannica Micropedia) are cell (biology) (with subarticles on organelles, protein synthesis and the like) and ecology (subarticles on Gaia theory etc.). Cell, ecology and cell metabolism are all major subjects that need discussion at length to be made sense of, so currently, all the material at both anabolism and catabolism are so short, that they should be merged, and when they are long enough split up (we are nowhere near that with cell metabolism). --Lexor|Talk 10:30, Nov 17, 2004 (UTC)
    Obviously, I agree with Lexor on this. Indeed, if there were some substance to the subtopics, it might be time to create the separate articles (it is not). As it is now, we have a stub leading to more stubs. All three of the points made above by Bensaccount (did he actually make these points?) are not served by the Bensaccount approach: 1) extraneous material under subheadings on one page is far easier to sort through than the same material spread over three articles; 2) Seems obvious—one page should suffice; and 3) By having more pages covering the same things, more versions will be slowly expanded on independent of each other. - Marshman 19:56, 18 Nov 2004 (UTC)
    When I made my comment the three points made sense since there were pages for anabolism and catabolism, as well there should be - these subjects deserve their own pages. Unfortunately, these pages no longer exist (a step in the wrong direction if you ask me). Bensaccount 03:34, 20 Nov 2004 (UTC)
    They do deserve their own articles at such time they grow large enough from the cell metabolism article to warrant one. Anabolism was less than a paragraph, and refers to catabolism and cell metabolism and is difficult to read in isolation. I suggest we could all working on beefing up this cell metabolism article and when it is sufficiently long and the anabolism and catabolism sections at least 7-8 good sized paragraphs, then split it off. --Lexor|Talk 12:40, Nov 20, 2004 (UTC)
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