Talk:Undulipodium

Intracellular NOT extracellular

Eukaryotic flagella and cilia are intracellular organelles. They are projections of the cell (cell membrane). --kupirijo (talk) 10:50, 6 November 2020 (UTC)

October 2009

flagella are also characteristic of many prokaryotes —Preceding unsigned comment added by 64.131.174.181 (talk) 20:47, 30 October 2009 (UTC)

Merge with axoneme?

This article is very similar to axoneme. Perhaps the two should be merged.--Chibibrain (talk) 02:38, 20 November 2009 (UTC)

Yes, similar, but according to the lead sentence in the Axoneme article ("Numerous eukaryotic cells carry whip-like appendages (cilia or eukaryotic flagella) whose inner core consists of a cytoskeletal structure called the axoneme."), not identical. As I read that sentence, the axoneme is a part of an undulipodia. As I understand it, "undulipodia" is just a general name for the two structurally identical cellular organelles cilia and flagella; however, as noted in both articles and in this one, there appears not to be a shred of a source for this Wiki-claim—there is no verifiable, reliable secondary source citation for the claim in any Wikipedia article I have seen.

Still, a merge proposal could be made by someone. Perhaps axoneme would make a good section of the undulipodium article, if we were ever to have a good source for what an undulipodium is. Cheers. N2e (talk) 01:16, 19 March 2010 (UTC)

And here is another paragraph, directly from a source, to clarify the difference: "Inside cilia and flagella is a microtubule-based cytoskeleton called the axoneme. The axoneme of primary cilia typically has a ring of nine outer microtubule doublets (called a 9+0 axoneme), and the axoneme of a motile cilium has two central microtubule doublets in addition to the nine outer doublets (called a 9+2 axoneme). The axonemal cytoskeleton acts as a scaffolding for various protein complexes and provides binding sites for molecular motor proteins such as kinesin II, that help carry proteins up and down the microtubules." That is from: Gardiner, Mary Beth (2005). "The Importance of Being Cilia". HHMI Bulletin. 18 (2). Howard Hughes Medical Institute. {{cite journal}}: Unknown parameter |month= ignored (help) N2e (talk) 18:40, 6 April 2010 (UTC)

Sources are missing

This article is, as of March 2010, entirely unsourced, although it has been fact-tagged for sources since July 2008. I will plan to begin to remove a lot of the unsourced material unless some sources are found.N2e (talk) 23:49, 18 March 2010 (UTC)

One potential source may be "<ref name=Haimo_JCB198112> {{cite journal | author = Haimo LT, Rosenbaum JL | title = Cilia, flagella, and microtubules | journal = J. Cell Biol. | volume = 91 | issue = 3 Pt 2 | pages = 125s–130s | year = 1981 | month = December | pmid = 6459327 | doi = 10.1083/jcb.91.3.125s | url = | pmc = 2112827 }}</ref>", a source used in both the cilia and flagella articles to source the assertion that "Eukaryotic cilia are structurally identical to eukaryotic flagella, although distinctions are sometimes made according to function and/or length." Unfortunately, the article is behind a paywall so is not accessible to ordinary web users. Does anyone have a copy, or might be able to obtain a copy from a research library? N2e (talk) 23:49, 18 March 2010 (UTC)

The most consensus is the use of cilium and flagellum for all purposes.

In "Usage", does the sentence "The most consensus is the use of cilium and flagellum for all purposes." have any salvageable meaning at all? If so could some kind person salvage it please? Thanks and best wishes DBaK (talk) 20:28, 9 July 2013 (UTC)

Confused

1st, if I'm not wrong, bacterial organelles of this kind have a rotating elememt, they like ATP sythase. Eukarotic organelles of this kind do not rotate. Archaeal organelles of this kind are more like bacterial ones, driven by ATP. So the eukarytoc organelles like the prokaryotic ones in function not by design. Afaik they are analogous, not homologous then.

2nd, "as primary cilia do not have the rotary movement mechanism found in motile cilia." - motile cilia Are organelles of eukaryota (as we see following the link). But I thought only the prokarotic organelle are rotating?

Please check! --Ernsts (talk) 19:39, 19 August 2017 (UTC)

Sharing new journal reference, and a review

The new journal

Lindemann, Charles B.; Lesich, Kathleen A. (2021). "The many modes of flagellar and ciliary beating: Insights from a physical analysis". Cytoskeleton. 78 (2): 36–51. doi:10.1002/cm.21656. ISSN 1949-3592. PMC 8048621. PMID 33675288.

My review

I believe "undulipodium" is a blanket term (hypernym) for cilium and flagellum, highlighting the fact that these two organelles are strikingly homologous, moreso compared to how supposedly analogous (debatable) they are to prokaryotic "flagella" – a misnomer for the prokaryotic macromolecular motors. Basically: "undulipodia" is "(eukaryotic) flagella", but which could also happen to be short and slightly biophysically different, otherwise making it "cilia" instead. "Eukaryotic flagella" is redundant, it should just be "flagella". Undulipodia (cilia and flagella) are motile extensions of eukaryotic cells, characterized by their common intracellular structure: the axoneme.

But basically: cilia and flagella are really the same thing; it would be nice if there's a common/generic name for them, named (superficially) after the motion that they have in common.

Undulipodia are differentiated between cilia and flagella according to their basal body, and usually by their motion – flagella are named so because they literally flagellate/whip in motion (usually). This is why "flagellum" for the bacterial organelle is a misnomer, because the prokaryotic organelles have more of a rotational (twirling) motion, rather than a "beating" (flagellating/undulating) motion – although sperm flagella also twirl, more or less. I would call the prokaryotic structures "propellosomes" if I had authority over what's universally accepted terminology among microbiologists. I've posted a topic on the talk page of Flagellum about my gripes with the current wiki article, which seems to conflate the prokaryotic protein complex with the eukaryotic protrusion. @Snoteleks replied with a suggestion that the article should split and that (eukaryotic) flagella should get its own article, so that the original article can more freely describe the prokaryotic organelles – which I agreed with and added that it, along with Cilium and Axoneme, should move to (or merge with) this Undulipodium article.

Also, I want to comment on how a lot of the sources on this article are quite old, with an overall (quite frankly outdated) bias, it seems, towards the notion that "undulipodia" has no merit or value in scientific literature or discourse, that it wouldn't be used – or just a general rejection of the very idea of using the term at all. Of course, as evident by at least one journal from this decade (which I just shared), that's not quite the case.

However, the problem with "undulipodia" is with the repeated misusage of the name/term, and the constant re-referencing – and, frankly, inappropriate attribution or conflation to/with – a postulation that was already been rejected (you know the one, with the "spirochetes" thing), furthering the undeserved discredit for the name/term. Like, "undulipodia" was somehow supposed to refer/relate to the debunked hypothesis that didn't even need bringing up (yet again), but the name/term is just chalked up to that now, for some reason.

It is disheartening to see there are still a few sources (from more recently) that continue to make the same mistakes when referring to undulipodia – as though they were: A) an entirely distinct/separate thing; B) a part within flagella/cilia (rather than being the whole flagella/cilia themselves); or C) a specific type of cilia or flagella – when it was supposed to be a hypernym to both cilia and flagella.

Really, confusion is the major issue with "undulipodium", not so much its supposed invalidity or lack of usage. I don't think it was trying to be a solution to a problem, I think it's just a useful generalization. CheckNineEight (talk) 04:28, 20 May 2025 (UTC)

@CheckNineEight I honestly haven't seen any source claiming it's not just a term for eukaryotic flagella/cilia; they are 100% the same structure. However, I have to disclose, as someone who interacts with other eukaryotic microbiologists, that the term is quite unpopular despite its usefulness. I'm not opposed to moving the necessary info to this article, but there's also the option to move it to a new article titled "Eukaryotic flagellum" instead, and start it with: The eukaryotic flagellum, also known as undulipodium or cilium.... Not sure what would be best right now, but maybe the second option would avoid the false perception that eukaryotic flagella aren't true flagella when it's the other way around. — Snoteleks (talk) 10:25, 20 May 2025 (UTC)

I meant that the word was being misused to mean something that is within (or a part of) the organelle, rather than the whole organelle itself being an undulipodium.

I'm going to repeat this again – and this is what I firmly believe: "eukaryotic flagellum" is redundant. "Flagellum" was already originally named for the eukaryotic organelle; it's "bacterial flagellum" (alternatively: "Flagellum (bacterial structure)" or other) that should get a name distinction, because theirs (bacteria) were identified at a much later time (if I'm not mistaken).

And no, I don't think cilia and flagella should be treated as synonymous; I'm pretty sure the former is distinct enough to be considered its own thing. It should be: cilia and flagella are two separate categories under undulipodia; not "undulipodia", "flagella" and "cilia" are alternative names for that thing.

See, this is what I was talking about when I said that confusion is the major problem of the term, and I feel like this is probably mainly the reason why the term is unpopular. I'm still baffled by "undulipodium" being unpopular. CheckNineEight (talk) 15:24, 20 May 2025 (UTC)