Talk:Mitochondrion

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• Talk:Mitochondrion/Archive_prior_talk

(first archived on 12-Nov-2008)

Topics from 2005

Rewrite

This article has been accepting a number of "1 line updates" over its history, and has become somewhat cluttered. Additionally, many of the entries are redundant ("cristae" were described a number of times, for example), and a number of the entries were opaque to a lay reader (such as unexamplined references to "alpha-proteo bacteria" and "matrix-targeting sequences", for example). I decided to undertake a large rewrite of this article, with the goals of reorganizing the information, and making it fully accessible to, say, a motivated middle school reader. Entries of more complexity should be pushed into specialized articles on the subject. – ClockworkSoul 17:44, 18 Mar 2005 (UTC)

Organisinisation of the mitochondrion associated articles

I've been looking at the articles that stem from this one and I think that we should consider the following changes:

• Merging Mitochondrial DNA and Mitochondrial genetics, probably keeping the Mitochondiral genetics title.
• Keeping and tidying Mitochondrial disease

--nixie 23:09, 10 Apr 2005 (UTC)

Topics from 2006

Mito and ATP Synthase

Dudes,

Mito actually are kind of threadlike, they're also round. I've seen lots of electron micrograph images in my cell class, my impression is that they are pretty fluid. But, i think it mostly depends on the cell. Mito in the axon of a neuron are going to arranged differently than those in a liver cell, etc.

Also, the image in the article depicts ATP synthase as floating around in the matrix. It's actually a transmembrane protien, actually that is essential to its function, as it is motivated by the flow of the H+ that have been pumped across the membrane.

Peace, --FoodRiot 04:53, 22 May 2006 (UTC)FoodRiot

This is a Good Article

After review, I've determined this article to meet the qualifications for good article status. Remember to keep up with the references for future edits, and continue to use the inline style whenever possible.

I do have a comment about the images. The two images seem to be roughly the same. One is just a very simple version of the other, but doesn't seem to add much in the way of its own information. I noticed a discussion a few months ago about some new images. What happened to those? The combination of a 'very simple' graphic and a 'more realistic' graphic makes sense.

Keep up the good work, folks. Remember, when making small changes, to read the surrounding paragraphs, and make small edits as necessary to make sure that your addition 'flows' into the rest of the article. It is easy for articles to end up as long lists of distinct sentences, if you take the time to read the entire paragraph, and 'flow' your addition in, it makes things much more readable. Feel free to message me on my talk page if you have any questions about my promotion rationale. Phidauex 17:31, 11 July 2006 (UTC)

Yeah! pschemp | talk 17:40, 11 July 2006 (UTC)

Very nice work! congrats to the editors that made this happen, you know who you are. ++Lar: t/c 19:33, 11 July 2006 (UTC)

This article may be a good article by editorial standards; the problem is that it doesn't have much to do with living breathing mitochondria. For starters, let's get a picture in the article of the network of mitochondria that you see when you do selective staining, taking a look at the mitochondria as they reside in cells -- in vivo, more or less in situ; well, they're alive, anyway. I am pretty sure that such pictures have been around for about twenty years now, since around 1987 or so.Richard8081 00:00, 4 July 2007 (UTC)

Aren't mitochondria more like a refinery than like a powerplant? Richard8081 00:00, 4 July 2007 (UTC)

Aging

I came to this article to look up the influence of Mitochondrial DNA on aging an I notice that it isn't in the article. Is this deliberate because the research is too new, or is it just because non one has added it in yet? Theresa Knott | Taste the Korn 22:56, 13 July 2006 (UTC)

• MtDNA like all DNA accumulates mutations - this has been linked to aging (i.e the older you are the more mutations there will be - which is espeically apparent in long-lived tissues like the brain; mitochondria also don't work as efficiently with age (in part due to accumulated mutations) which can also cause phenotypes) - but from a quick look at PubMed no one has really shown how MtDNA degeneration directy affects aging.--Peta 23:10, 13 July 2006 (UTC)
  • I read something in the new scientist (I don't have the copy in question any more) that stated that recent research linked mitochondrial DNA directly to aging. After all short lived tissues like skin also age. I didn't understand the mechanism though :-( Theresa Knott | Taste the Korn 23:39, 13 July 2006 (UTC)

He we go - a little light reading for anyone who is interested.

Review paper [1] "Several hypotheses suggest that defective mitochondria contribute to, or are responsible for, ageing. Recent observations indicate that mitochondria in an old organism differ in many respects from those in a young organism."

Letters to Nature[2] "Our results thus provide a causative link between mtDNA mutations and ageing phenotypes in mammals."

I don't know enough biology to write anything up myself I'm afraid What you you guys think? Theresa Knott | Taste the Korn 23:49, 13 July 2006 (UTC)

Later work on the mutator mouse (from the second article you cite) proposes that the aging phenotype is caused by respiratory chain failure rather than the mutations; suggesting that loss of mitochondrial function is a major causal factor in aging rahter than mutations in mtDNA. To quote a letter to Science (310:411) - "Whether the rate of aging depends critically on mitochondrial mutations is still very much an open question".

We should probably add a mention of the theory, but at this point is is just a theory.--Peta 00:20, 14 July 2006 (UTC)

I agree with Peta's remarks. I followed a course on biology of ageing some years ago, and it's clear that ageing cannot be attributed to a single process, there are many important, different processes going on. Please consider this when writing about the research. Jens Nielsen 13:13, 14 July 2006 (UTC)

That's all I'm asking for. A brief mention of the theory with a statement that it's still a top[ic or research and debate. Theresa Knott | Taste the Korn 20:23, 15 July 2006 (UTC)

Peer Review

This article has been listed at Peer Review. Please take the time to read the suggestions made at Wikipedia:Peer review/Mitochondrion and improve the article if you can. The biggest issue is references, anyone who can contribute in that area would be appreciated. I think that this article can become a Featured Article with just a little more work, so let's do it. pschemp | talk 01:46, 17 July 2006 (UTC)

mitochondria in forensics

I propose the creation of a new section for the use of mitochondrial DNA in forensics. Mitochondrial DNA can be used to determine indentity when nuclear DNA is not available. If there are no objections, I will get started on this soon! Lauren 15:47, 29 August 2006 (UTC)

25% of the cell's cytoplasm

'Usually a cell has hundreds or thousands of mitochondria, which can occupy up to 25% of the cell's cytoplasm.' Can anyone cite that? Also- by weight, volume, or some other, more esoteric, measure?

That's probably easy: Molecular Biology of the Cell, by Alberts et al. Here's the book's web site: http://www.garlandscience.com/textbooks/0815332181.asp I glanced through my copy, but couldn't find those numbers--but the book is over 1000 pages long, so it's not surprising I didn't find it. This is one of those numbers I see quoted in the literature all the time, but without citation. :( As for the 25%, that is probably by both weight and volume--I don't expect there to be huge differences between cytosolic density and mitochondrial density, and that number is probably fairly rough anyway. ~Doc~ EquationDoc 05:08, 10 November 2006 (UTC)

Topics from 2007

Mitochondrial pH

Articles always mention the fact that protons are driven accross the membrane to drive ATP formation, but what is the actual pH accross these membranes? I'm very interested to hear about how much this varies, because, of course, pH is integral to protein structure. When we add something that uncouples phosphorylation, like dinitrophenol, would this affect the mitochondrial proteins? There's a massive proton gradient, surely there's a pH gradient too? Does this change intracellular pH in the local vicinity of the mitochondrion too?Jph53 17:05, 14 March 2007 (UTC)

Good point. FYI the pH gradient is 1 (10 fold concentration difference). In chloroplasts it is a whopping 4 pH units difference between the lumen (pH4) and the stroma (pH8). Both electrochemical gradients drive the ATP synthase and actually have about the same energy potential despite the large concentration difference in protons. The mitochondrial inner membrane has a negative charge on matrix side compared to the inner membrane space side. This charge makes up the difference in the mitochondria such that the mito and chloroplast proton gradients have roughly the same electrochemical potential when ATP synthesis is active. There is no charge across the choroplast thylkoid membrane. David D. (Talk) 18:26, 14 March 2007 (UTC)

Mitochondrial number and volume

The concept that there is a typical eukaryotic cell with 2000 mitochondrion is confusing. Mitochondrial number is specific to tissue and organism type. I suggest that this line be replaced with something like "Mitochondrion number varies immensely according to organism and tissue type. Many cells possess only a single mitochondrion, while others can contain several million. Molecular Biology of the Cell, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter, ISBN 0815332181 --Spamburgler 02:30, 24 April 2007 (UTC)

Is this "single mitochondrion" a filamentous network of, well, mitochondria? Richard8081 20:31, 15 August 2007 (UTC)

Well? Anyone? Richard8081 (talk) 13:45, 10 June 2008 (UTC)

The kinetoplast in protozoa like Trypanosoma brucei is a single mitochondrion with a single continuous mitochondrial matrix. It extends the length of the cell. Tim Vickers (talk) 16:10, 10 June 2008 (UTC)

fungus or protozoa

Cryptosporidium is not a fungus —The preceding unsigned comment was added by 201.143.135.81 (talk) 22:08, 6 May 2007 (UTC).

"Death Center"

I was just reading a New Scientist article ( http://www.newscientist.com/channel/health/mg19626252.300-death-special-back-from-the-brink.html;jsessionid=LCNFCHIBIPGB ) and it had an interview where he states that they are hypothesising that the mitchondria are also the "death center" for the cell and can trigger death in a variety of circumstances. Is this worth a mention? just thought i would bring it to attention... Helmet Shell 13:28, 15 October 2007 (UTC)

Resubmission for featured article status?

Anybody know what it will take to resubmit this for FA review? There have been huge improvements since July 2006 when it was reviewed, and nearly all the criticisms in the review have been implemented. The number of references has gone up 10-fold since then as well. Sedmic 16:37, 4 November 2007 (UTC)

First check the Featured Article criteria, and if the article has met them, you can submit it for review at WP:FAC. –panda 16:12, 1 December 2007 (UTC)

I think this article may meet criteria for FAC. I just submitted it for peer-rereview. After working on this for a while, I'm looking for suggestions on new areas to improve within the article to get it to FA status. What else should be in this article to make it complete without being unnecessarily long? Thanks! Sedmic 21:22, 7 December 2007 (UTC)

Article nominated for WP:FAC. I don't see much more coming in the way of peer review. Sedmic 17:45, 16 December 2007 (UTC)

A few inaccuracies/unclarities

Even though the article for the large part is very good, it includes a few points that could be clarified better.

• As the mitochondrial content of a cell is in a constant flux of fusing and division (example review[3], visual representation here [4]), it might be better to refer to it as "the mitochondrial network". Likewise, it is usually more accurate to use the copy-number of the mitochondrial DNA in the cell as a whole as a measure of mitochondrial content. "MtDNA/mitochondrion" is a meaningless measure due the mentioned dynamics of the mitochondrial network.
• When talking about the mitochondrial genome, it should be made clear that it is the human one being talked about. This as other species have fewer or more genes in mtDNA, and the mtDNA of different species is dramatically different in lenght (plant mitochondrial DNA especially are often very large), ie mtDNA is not by definition ~16kb. There is also a wierd choice of words in this section "and many chromosomes are circular". Almost all mtDNA is circular, linear mtDNA must be said to be the rare exeption [5].
• It has recently been shown by several groups that increased reactive oxygen species is not coupled with mitochondrial mutations linked with ageing. (example[6]).

Any comments? --Lensor (talk) 09:57, 26 November 2007 (UTC)

These are all really good comments. I'd invite you to just make the changes yourself and any other corrections/copy editing. Is there any reason why you'd prefer not too? David D. (Talk) 10:01, 26 November 2007 (UTC)

None really, just that they might be viewed as controversial (especially the ageing comment), and I wanted to get comments first.--Lensor (talk) 10:04, 26 November 2007 (UTC)

I think the PNAS paper you linked is great. I missed it when I originally wrote the paragraph on ROS. There's a lot of controversy still, but this paper certainly deserves mention. I'm adding it in now. Please alter/add if you think it needs further clarification or you disagree with what it says. Sedmic 15:38, 7 December 2007 (UTC)

daltons?

>> "These porins form large aqueous channels that permit the passage of molecules 5000 daltons or less."

• The link to daltons goes to an article about a newspaper (I think. Not sure :). I'll fix the hatnote in a bit.
• to make it easier to read to a dimwit like me, could perhaps the trailing clause read "... molecules that are 5000 daltons or less in weight"?

Thanks. -- Fullstop (talk) 20:44, 16 December 2007 (UTC)

Thanks for the suggestions. I moved the daltons link to Atomic mass units and changed the sentence as requested. Sedmic 00:43, 17 December 2007 (UTC)

external links

• Template:PLoSlink
• Information on Mitochondrial Diseases at circuitblue.com
• Mitochondria and Aging at circuitblue.com

i removed the three above since they should probably be cited in the text at the apropriate place, if appropriate, rather than exist as external links. David D. (Talk) 21:23, 16 December 2007 (UTC)

I added the PLOS Bio article which that summary referred to in to the main page. The circuitblue.com pages are interesting summaries with possibly useful bibliographies, but I don't know that they necessarily add anything new other than more papers to read if interested? Sedmic 00:39, 17 December 2007 (UTC)

I added the mitochondria and aging link as a reference in the aging section at the end.--Xris0 (talk) 03:47, 11 May 2008 (UTC)

Genome/mtDNA

There is a genome section in this article and two separate articles on mitochondrial DNA (mtDNA) and mitochondrial genome which was proposed for a merge with mtDNA. Which one should be the main article for the genome section in this one? - tameeria (talk) 19:34, 30 December 2007 (UTC)

I agree that mitochondrial DNA and mitochondrial genome should probably be merged. As it stands, I favor mitochondrial DNA as the main linked article from mitochondria because it has more facts and is better sourced. However, there are many details in the mitochondria section on genome that are missing from the mitochondria DNA article. Maybe some of these items can be transferred in the future ... Sedmic 17:31, 1 January 2008 (UTC)

CMS in plants

Mitochondria can be involved in cytoplasmic male sterility in plants. This should probably at least be mentioned in the article. - tameeria (talk) 19:45, 30 December 2007 (UTC)

Topics from 2008

Apparent Contradiction in Origins section

At the moment, it says:

A few groups of unicellular eukaryotes lack mitochondria: the microsporidians, metamonads, and archamoebae.[35] These groups appear as the most primitive eukaryotes on phylogenetic trees constructed using rRNA information, suggesting that they appeared before the origin of mitochondria. However, this is now known to be an artifact of long branch attraction – they are apparently derived groups and retain genes or organelles derived from mitochondria (e.g., mitosomes and hydrogenosomes).[1] There are no primitive eukaryotes today that lack mitochondria.

The first bolded sections appears to contradict the second, can someone who knows which is correct edit out the incorrect section? Or resolve the apparent contradiction - JackAidley (talk) 15:22, 8 January 2008 (UTC)

Mitochondrion image

It would be useful to know what tissue the mitochondrion image in the lede came from, and what size the organelle is (no scale is provided or statement of magnification). Also, the resolution of that image is disappointing, too low to show details of the cristae, or relationships between inner and outer membranes. Any chance of a better picture, or a better version of the same one with more details of origin and a scale? Plantsurfer (talk) 10:04, 6 September 2008 (UTC)

See Category:Mitochondria. Tim Vickers (talk) 15:58, 6 September 2008 (UTC)

OK Thanks, that'll do nicely Plantsurfer (talk) 16:38, 6 September 2008 (UTC)

Copy number

The article now mentions that the number of mitochondria per cell varies from thousands (in muscle cells) to one. Someone who has relevant sources please expand on this, and include plants. This is a point of interest to readers of several medical articles, including Gout. Other information of interest, apart from copy number, are the variations in total DNA and RNA content of mitochondria. --Una Smith (talk) 14:02, 24 October 2008 (UTC)

I was thinking that the entire "organization and distribution" section could do with a rewording, This as what we today know about the organization of mitochondria not as discrete units, but as a constantly fusing and dividing network, makes it in essentially pointless to talk about mitochondrial copy number. A better measuring unit is mitochondrial DNA copy number. Alternatively mitochondrial mass.--Lensor (talk) 13:28, 1 April 2009 (UTC)

Retrofit topic year headers/subpages

12-Nov-2008: I have added subheaders above as "Topics from 2005" (etc.) to emphasize the dates of topics in the talk-page. Older topics might still apply, but using the year headers helps to focus on more current issues as well. The topic-year boundaries were located by searching from bottom for the prior year#. Afterward, I dated/named unsigned comments and moved 4 entries (including "Endosymbiotic theory" & "Mitochondrial pH") into date order for 2002, 2006 & 2007.
Then I added "Talk-page subpages" above the TOC. -Wikid77 (talk) 06:10, 12 November 2008 (UTC)

Technical article denied FA status

12-Nov-2008: I noticed the article was denied "Featured-article" status due to several sentences containing more than 3 technical terms. Based on that rejection, few tech articles can qualify. Would "Quadratic equation" be denied FA-status unless equation and algebra were also explained in that article to avoid using outside technical terms? Meanwhile, "Mitochondrion" is a very good tech article, but I can't see it ever becoming "Introduction to Mitochondrion" for the beginner. Seems like the FA-criteria tend to exclude tech articles that have lots of details. -Wikid77 (talk) 06:10, 12 November 2008 (UTC)

Created talk-page archive

12-Nov-2008: I just now created Talk:Mitochondrion/Archive prior talk (after 6 years of entries), and moved 25 older topics (60%) to that file, such as 2003 content debates & "need help with science project" or such. The entries there are in the same order, grouped under "Topics from 2005" (etc.), but it might be years before more need to be moved there. -Wikid77 (talk) 06:59, 12 Nov 2008