Talk:Mitochondrion

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Use in Population Genetic Studies

Quoth the article, "Because of the unique matrilineal transmission of mitochondrial DNA, scientists in population genetics and evolutionary biology often use data from mitochondrial DNA sequences to draw conclusions." Scientists use data to draw conclusions?? Shocking! I am not knowledgeable enough to expand this into a more informative sentence. Albatrossish 05:22, 18 March 2006 (UTC)[reply]

Endosymbiotic theory

More information about mitochondiral DNA and endosymbiosis theory is needed here! Some is available at

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Endosymbiosis.html

Different page

This should rather go to endosymbiotic hypothesis or a new page, I guess.

Aragorn2 15:25, 16 Sep 2003 (UTC)

non-photosynthetic eukaryotes

can you give an example of one without mitochondria? I'm skeptical.168... 08:14, 11 Jan 2004 (UTC) Never mind. I found the Diplomonadida.168... 08:18, 11 Jan 2004 (UTC)

mtDNA recombination possible in humans

Hopefully it has been noticed that Kreytsberg et al. have released a shocking paper. Although it doesn't directly refute the use of mtDNA as a marker in population genetics, it casts doubt on this method.

I have changed the article to reflect this. I refer to ' Kraytsberg et al., Recombination of Human Mitochondrial DNA, Science 2004 304: 981'.

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 unexmaplined 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. – Clockwork Soul 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)

Interesting theory or established fact?

I can't recall where but I seem to remember hearing that mitochondria may have been one of the first lifeforms in the primeval sea and started out as an independent lifeform which may later on have struck up some kind of mutually beneficial relationsship with another lifeform thus becoming the foundation of all life that it is today. Was that just nonsense? If not I think it deserves some mention because it is frightfully interesting isn't it? Preisler 21:19, 25 Apr 2005 (UTC)

Ah it's already mentioned I see.. The bio lingo in the first couple of paragraphs made me skip it.. This article really is a bit hard to read for the layman..

That's a side effect of the fact that this article is mostly edited by people specifically interested in cell biology, whch tends to be individuals involved in the field, or at least studying it at the university level. Without looking again at the article myself, may I ask which parts you found the most difficult? – Clockwork Soul 18:42, 4 December 2005 (UTC)[reply]

Author Help

Who are the authors that wrote this article? How should I cite this article for my report? I need help in this area. Mitochondria are so interesting! For those who haven't, I suggest you read A Wind in The Door by Madeline L'Engle- it's an amazing fictional/factual story on mitochondria suggesting that farandolae might exist on mitochondria.

There are numerous contributors—from the article page, click the "history" tab to see all the people who have worked on this article. To see how to cite the article, please click on the "cite this article" link in the toolbox to the left of the article. Hope this helps! — Knowledge Seeker দ 18:34, 4 December 2005 (UTC)[reply]

Of course, it bears repeating that encyclopedia (and especially Wikipedia) articles should generally not be used as sources except in a very general way. Albatrossish 05:19, 18 March 2006 (UTC)[reply]

Yeah, I read A Wind in the Door. It's a great book. I'm planning to write some more for this article, about recent studies. By the way, do you think someone should add a section to this article called "Mitochondia in Fiction?" 208.38.46.5

Dropped paragraph

There is a paragraph in Use in population genetic studies section in rev.38776689 which somehow got dropped when reverting vanadalism. It may contain relevant information but I cannot judge. The paragraph reads: Recent studies have, however, cast doubt on this hypothesis. Kraytsberg et al. showed that mitochondrial recombination is possible in humans (Science 304:981, May 2004, pubmed #15143273).

image for mitochondrion (light microscope)

I've taken the liberty of removing the Image:Mitochondria in cell.jpg from the top in support of the comment from Rob at the top of the talk page. Though I am not familiar with light microscopy of mitochondria, I have several electron microscopy images in my 'molecular biology of the cell', and they all show structures much more resembling the diagram, and certainly without any threadlike structures. The light microscopy image does not add much information and perhaps even adds some confusion. Jens Nielsen 10:53, 10 February 2006 (UTC)[reply]

has my support Adenosine | Talk 09:08, 12 February 2006 (UTC)[reply]

Percentage of cytosol or cytoplasm?

Re "[mitochonria] can occupy up to 25% of the cell's cytosol". Since the cytosol is the portion of the cytoplasm without the organelles, logically mitochonria cannot "occupy" any part of the cytosol. A-giau 06:35, 14 February 2006 (UTC)[reply]

Well seen. I've changed it accordingly (don't hesitate to do so yourself if you spot such mistakes - just add explanation).

A related point: Can anyone confirm the 25% figure? A citation would be good to have. Jens Nielsen 21:18, 14 February 2006 (UTC)[reply]

Revised: Comment on Images in Mitochondrion Entry

The previous light microscopic image of a mitochondrial reticulum in a cell that was removed in February should be restored. Mitochondria are a dynamic reticulum in most cells, with long and short cylinders fissioning and fusing to form an elaborate branched network. The football shape in textbooks is a throwback to a time before three dimensional confocal fluorescence and electron tomographic imaging. It is also biased by results with isolated mitochondria, which do tend to be more round.

The current cartoon is also inaccurate in the representation of cristae as random infoldings. They are invaginations that originate at tubular openings into the boundary or peripheral region of the inner membrane. I have uploaded a model (MitoModelCAM.jpg) based on electron tomography that shows this. (I'd be happy to work with whoever drew the cartoon to help make it more accurate. I think a simple fix is possible.) You can also click on the website links (on the top page of the mitochondrion entry) for the national microscopy centers in Albany NY and San Diego CA that have been generating 3D images of mitochondria for over 10 years.

(I hold the copyright to the uploaded image and hereby release it into the public domain.)

Carmmann 19:38, 5 March 2006 (UTC)[reply]

I would suggest 2 images be used in this article - one simplified one (such as the current one) which shows clearly the main structure, plus another which is more accurate in a real situation. --Scohoust 14:23, 18 March 2006 (UTC)[reply]

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[reply]

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)[reply]

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

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)[reply]

^{[citation needed]}

Why do you doubt this statement? If it didn't undergo destruction soon after fertilization then mitochondiral inheritence *wouldn't* be matrilineal. pschemp | talk 04:13, 13 July 2006 (UTC)[reply]

For reference, the article sentence I tagged with {fact} was:

"However, the mitochondria provided by the sperm are targeted for destruction very soon after entry into the egg."

I would like a source for this because there are many other possible mechanisms which could cause matrilineal inheritance of mitochondrial genes. Just offhand I can come up with these alternatives:

the paternal mitochondria aren't transferred into the egg by the sperm or aren't permitted to enter by the egg.
only the nucleus enters the egg
all entering material is transferred to the egg's nucleus, where the paternal mitochondria cannot reproduce
the paternal mitochondria in the cytosol are not permitted to reproduce by some mechanism, thus being diluted into essential nonexistence eventually

Given that there are many possible ways to explain matrilineal inheritance, it seems like the article should support the particular assertion it makes. Whatsmore, the particular mechanism of targetting is of interest. -R. S. Shaw 05:02, 13 July 2006 (UTC)[reply]

The original statement was correct, and I replaced it with the correct source reference. (It had been replaced by a mistake with a general textbook cited -- not good.) 209.11.184.1 08:41, 16 July 2006 (UTC)[reply]

That's not a mistake, that was a correct, sourced statement from a college level textbook. If you can prove it is wrong, please do, but you'll have to find a source. Don't arbitrarily remove things like that if you don't know what you are doing please. pschemp | talk 15:05, 16 July 2006 (UTC)[reply]

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)[reply]

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)[reply]
- 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)[reply]

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)[reply]

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)[reply]

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)[reply]

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)[reply]

Need a microscope picture at top

Since the duplicate diagram was removed, it would be good to have a microphotograph up at the top of the article next to the intro. I recommend this one. It is free because it is a product of a US government agency. Its caption is: Electron micrograph of a single mitochondrion showing the organized arrangement of the protein matrix and the inner mitochondrial membranes. (Photo: U.S. Dept. of Health and Human Services/National Institutes of Health)[3]

I would upload it but the silly public terminal I'm on will not let me save images to disk. 209.11.184.1 06:58, 16 July 2006 (UTC)[reply]

I uploaded it for you. Here is the image: Image:Mitochondrion 186.jpg. Its a little small but better than nothing. David D. (Talk) 07:07, 16 July 2006 (UTC)[reply]

Thanks! 209.11.184.1 08:41, 16 July 2006 (UTC)[reply]

Eloping mitochondrion

I remember when I were younger, we learned that since the mitochondria has it's own set of DNA, it could easily escape. I remember talking to my teacher a lot about this, but haven't really found anything in those words exactly about it! Was he just pulling my leg, or is this a possibility, if so, should it be included in the article, or is it too un-scientific? — Preceding unsigned comment added by 85.166.199.220 (talk)

Pulling your leg. A good bit of the original DNA a mitochondria had has been transferred to the nucleus of eukaryotic cells, therefore, it doesn't have everything it needs to survive outside the cell. pschemp | talk 15:07, 16 July 2006 (UTC)[reply]

yes, but it could still "escape" (if you can follow) and the consequences I believe would be fatal. Or maybe I'm trying to say, there is nothing that really constitutes the mitochondria to stay, they just choose to! (erh... this might seem naïve, it was just a childhood fascination that I suddenly remembered)85.166.199.220 15:24, 16 July 2006 (UTC)[reply]

No, it can't escape. They don't choose to be there, because they can't "choose" to do anything. In fact, the cytoskeleton holds them in place somewhat. Like I said before, mitochondria do not have the nesseccary DNA to live outside the cell, or to "choose" anything. They are completely dependent on the cell, and the cell on them. I think you may be thinking about Endosymbiotic theory which may explain their original configuration as free bacteria, but the mitochondria around today have changed too much to be able to "choose" to leave the cell. Also see the fiction section of this article, there was a sci-fi book written about mitochondria that revolt, perhaps you are mixing fact with fiction. pschemp | talk 18:37, 16 July 2006 (UTC)[reply]

Sperm mitochondria - do they go in the egg at fertilisation?

In reply to the anon edits, there is one single documented instance where a mitochondrion entered the egg cell at fertilisation. The evidence was that the transmitted mitochondrion caused the same medical condition in the son as in the father (it was a kind of fatigue syndrome that meant that light physical work would quite exhaust both men, trivially a mitochondrial problem). I don't have the reference here, but the basic message is that this transfer is still thought to be very, very rare. The exception should probably be mentioned if someone can find the reference. - Samsara (talk • contribs) 19:01, 16 July 2006 (UTC)[reply]

This one is in the article already - Is that it? pschemp | talk 19:03, 16 July 2006 (UTC)[reply]

Johns, D. R. (2003). "Paternal transmission of mitochondrial DNA is (fortunately) rare". Annals of Neurology. 54: 422–4.