Copyright © Philip M. Parker, INSEAD. Terms of Use.
Definition: Flagellum |
FlagellumNoun1. A whip used to inflict punishment (often used for pedantic humor). 2. Long lash-like appendage used for locomotion (e.g., in sperm cells and some protozoa). Source: WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved. |
Etymology: Flagellum \Fla*gel"lum\, noun; plural English Flagellums, from Latin expression Flagella. [Latin expression, whip. See Flagellate, transitive verb]. (references) |
| Domain | Definition |
Medicine | A whiplike appendage of a cell. It can function either as an organ of locomotion or as a device for moving the fluid surrounding the cell. Source: European Union. (references) |
Source: compiled by the editor from various references; see credits. | |
(From Wikipedia, the free Encyclopedia)
The flagellum (plural: flagella) is a propulsive structure used by many single-celled organisms to move through a liquid medium. There are three main varieties of flagellum; the bacterial flagellum (a helical filament that rotates like a screw), archaeal flagellum (similar but nonhomologous to the bacterial flagellum), and the eukaryotic flagellum (a whip-like structure that lashes back and forth).
Bacterial flagellum
The filament is composed of the protein flagellin and is a hollow tube 20 nanometers thick. It is helical, and has a sharp bend just outside the outer membrane called the "hook" which allows the helix to point directly away from the cell. A shaft runs between the hook and the basal structure, passing through protein rings in the cell's membranes that act as bearings. Gram-positive organisms have 2 rings, one in the cell wall and one in the cell membrane. Gram-negative organisms have 4 rings, 2 in the cell wall and 2 in the cell membrane.
The bacterial flagellum is driven by a rotary engine composed of protein, located at the flagellum's anchor point on the inner cell membrane. The engine is powered by proton motive force, i.e., by the flow of protons across the bacterial cell membrane due to a concentration gradient set up by the cell's metabolism (in Vibrio species the motor is a sodium ion pump, rather than a proton pump). The rotor transports protons across the membrane, and is turned in the process. The rotor by itself can operate at 6,000 to 17,000 rpm, but with a filament attached usually only reaches 200 to 1000 rpm.
The components of the flagellum are capable of spontaneous assembly in bacterial membranes. Both the basal structure and the filament have a hollow core, through which the component proteins of the flagellum are able to move into their respective positions. The basal structure has many traits in common with some types of secretory pore which have a hollow rod-like "plug" in their centers extending out through the cell wall, and it is thought that bacterial flagella may have evolved from such pores.
Different species of bacteria have different numbers and arrangements of flagella. Monotrichous bacteria have a single flagellum. Lophotrichous bacteria have multiple flagella located at the same spot on the bacteria's surface which act in concert to drive the bacteria in a single direction. Amphitrichous bacteria have a single flagellum each on two opposite ends (only one end's flagellum operates at a time, allowing the bacteria to reverse course rapidly by switching which flagellum is active). Peritrichous bacteria have flagella projecting in all directions.
Some species of bacteria (those of Spirochete body form) have internal flagella that lie between their inner and outer membranes, the rotation of which causes the entire bacterium to corkscrew through its medium.
Anticlockwise rotation of monotrichous polar flagella thrusts the cell forward with the flagellum trailing behind. Periodically the direction of rotation is briefly reversed, causing what is known as a "tumble", and results in reorientation of the cell.
An excellent introduction to the bacterial flagellum is given by Berg, here:
http://www.aip.org/pt/jan00/berg.htm (in Physics Today)
The bacterial flagellum is proposed by Michael Behe as an example of irreducible complexity. See also: evolution of flagella.
Archaeal flagellum
The archaeal flagellum is another prokaryote flagellum that is found exclusively in the archaea (also known as archaeabacteria, depending on whether or not one believes that these prokaryotes constitute a fundamental domain of life (e.g., Woese), or a just a highly-derived bacterium with heavy adaptation to extremophily, particularly thermophily (e.g., Cavalier-Smith)).
The archaeal flagellum is superficially similar to the bacterial (or eubacterial) flagellum; in the 1980s they were thought to be homologous on the basis of gross morphology and behavior (Cavalier-Smith, 1987). Both flagella consist of filaments extending outside of the cell, and rotate to propel the cell.
However, discoveries in the 1990s have revealed numerous detailed differences between the archaeal and bacterial flagella; these include:
These differences mean that the bacterial and archaeal flagella are a classic case of biological analogy, rather than homology; however, in comparison to the decades of well-publicized study of bacterial flagella (e.g. by Berg), archaeal flagella have only recently begun to get serious scientific attention. Therefore many assume erroneously that there is only one basic kind of prokaryotic flagellum, and that archaeal flagella are homologous to it (an example is Cavalier-Smith (2002), who is aware of the differences in archaeal and bacterial flagellins, but retains the misconception that the basal bodies are homologous).
- Bacterial flagella are powered by a flow of H+ ions (or occasionally Na+ ions); archaeal flagella are almost certainly powered by ATP.
- Bacterial flagella grow by the addition of flagellin subunits at the tip; archaeal flagella grow by the addition of subunits at the base.
- Bacterial flagella are thicker than archaeal flagella, and the bacterial filament has a large enough hollow "tube" inside that the flagellin subunits can flow up the inside of the filament and get added at the tip; the archaeal flagellum is too thin to allow this.
- Many components of bacterial flagella share sequence similarity to components of the Type III secretion systems (TTSS); the components of bacterial and archaeal flagella share no sequence similarity, however, some components of archaeal flagella share sequence similarity with Type IV secretion systems, also known as Type IV pili.
Eukaryotic flagellum
The eukaryotic flagellum, also called a cilium or undulipodium, is completely different from the prokaryote flagella in structure and in evolutionary origin. The only thing that the bacterial, archaeal, and eukaryotic flagella have in common is that they stick outside of the cell and wiggle to produce propulsion.
A eukaryotic flagellum is a bundle of nine fused pairs of microtubules called "doublets" surrounding two central single microtubules (the so-called 9+2 structure; also called the "axoneme"). At the base of a eukaryotic flagellum is a microtubule organizing center about 500 nanometers long, called the basal body or kinetosome. The flagellum is encased within the cell's plasma membrane, so that the interior of the flagellum is accessible to the cell's cytoplasm. This is necessary because the flagellum's flexing is driven by the protein dynein bridging the microtubules all along its length and forcing them to slide relative to each other, and ATP must be transported to them for them to function.
For information on biologists' ideas about how the various flagella may have evolved, see evolution of flagella.
Source: adapted by the editor from Wikipedia, the free encyclopedia under a copyleft GNU Free Documentation License (GFDL) from the article "Flagellum."
Synonym: FlagellumSynonym: scourge (n). (additional references) |
Crosswords: Flagellum |
| English words defined with "flagellum": choanocyte, collar cell ♦ Flagella, flagellate, flagellated, flagellated cell, Flagellums ♦ genus Euglena ♦ Procerite ♦ Uniflagellate ♦ whiplike. (references) |
| Specialty definitions using "flagellum": Fossa et Furca, Furcam et Flagellum ♦ Trichomonas, Tritrichomonas foetus. (references) |
| Etymologies containing "flagellum": Flagelliform. (references) |
| Non-English Usage: "Flagellum" is also a word in the following language with English translations in parentheses. Latin (arm, flail, lash, scourge, tentacle, thong, vine shoot, whip). |
| Thumbnail | Description & Credit | Thumbnail | Description & Credit |
 | Weeks Bay National Estuarine Research Reserve. A coachwhip snake - Masticophis flagellum. Credit: National Estuarine Research Reserve System (NERR). |  | Pl. XLVIII. 176. Cyema atrum, Gunther. From Gunther, Challenger Report, Vol. XXII. 177. Eurypharynx pelecanoides, Vaillant. From Vaillant, "Exped. Scient. du Travailleur et du Talisman." 178. Saccopharynx flagellum, Mitchill. From Gunther, Challenger Report, Vol. XXII. Credit: National Marine Fisheries Historical Image Collection. |
 | Pl. XLIX. 179, 180. Saccopharynx flagellum, Mitchill. At N. Lat. 38.4, W. Lon. 71.2, in 1615 fathoms. 181,182. Gastrostomus Bairdii, Gill and Ryder. At N. Lat. 41.7, W. Lon. 65.4, at 1309 fathoms. Credit: National Marine Fisheries Historical Image Collection. | ||
Source: pictures compiled by the editor from various references; see picture credits. | |||
| "Flagellum" is generally used as a noun (singular) -- approximately 100.00% of the time. "Flagellum" is used about 9 times out of a sample of 100 million words spoken or written in English. Its rank is based on over 700,000 words used in the English language. Some parts-of-speech are not covered due to the samples used by the British National Corpus. (note: percents less than one-hundredth of one percent have been omitted) |
| Parts of Speech | Percent | Usage per 100 Million Words | Rank in English |
| Noun (singular) | 100% | 9 | 117,287 |
Source: compiled by the editor from several corpora; see credits.
Expression using "flagellum": Masticophis flagellum. Additional references. | |
| Source: compiled by the editor from various references; see credits. |
| The following statistics estimate the number of searches per day across the major English-language search engines as identified by various trade publications. Hyperlinks lead to commercial use of the expression at Amazon.com. |
| Expression | Frequency per Day |
flagellum | 9 |
flagellum masticophis | 2 |
bacterial flagellum | 2 |
| Source: compiled by the editor from various references; see credits. | |
| Language | Translations for "flagellum"; alternative meanings/domain in parentheses. | |
Albanian | zgjatim (elongation, extension), kamzhik (discipline, horsewhip, knout, lash, quirt, scourge, sjambok, switch, whip), degë zvarritëse, bisht (tail). (various references) | |
Chinese | 鞭毛 . (various references) | |
Danish | Bailey's flagelfarvemetode (Bailey flagellum staining). (various references) | |
French | flagelle. (various references) | |
German | geißel (scourge). (various references) | |
Greek | χρώσις βλεφαρίδος κατά BAILEY (Bailey flagellum staining), χρώσις μαστιγίου κατά BAILEY (Bailey flagellum staining). (various references) | |
Italian | flagello (plague, scourge). (various references) | |
Japanese Kanji | 鞭毛 . (various references) | |
Japanese Katakana | べんもう. (various references) | |
Pig Latin | agellumflay.(various references) | |
Spanish | coloración de los cilios de Bailey (Bailey flagellum staining). (various references) | |
Swedish | flimmerhår (cilium). (various references) | |
| Source: compiled by the editor from various translation references. | ||
| Language | Date | Source | Proverbs Chapter 26, Verse 3 |
| Latin | 405 | Vulgate | Flagellum equo et camus asino et virga dorso inprudentium |
| Middle English | 1395 | Wyclif | A scourge to an hors, and a bernacle to an asse; and a yerde in the reg of vnprudent men. |
| Jacobean English | 1611 | King James | A whip for the horse, a bridle for the ass, and a rod for the fool's back. |
| Victorian English | 1833 | Webster | A whip for the horse, a bridle for the ass, and a rod for the fool's back. |
| Basic English | 1964 | Ogden | A whip for the horse, a mouth-bit for the ass, and a rod for the back of the foolish. |
Source: compiled by the editor from various references; see credits. | |||
| Language | Proverbs Chapter 26, Verse 3 |
| Cebuano | ¶ Usa ka pudlos alang sa kabayo, usa ka busal alang sa asno, Ug ang usa ka bunal alang sa likod sa mga buang. |
| Chinese | 鞭 子 是 為 打 馬 ． 轡 頭 是 為 勒 驢 ． 刑 杖 是 為 打 愚 昧 人 的 背 。 |
| Croatian | Biè konju, uzda magarcu, a šiba leðima bezumnika. |
| Danish | Svøbe for Hest, Bidsel for Æsel og Ris for Tåbers Ryg. |
| Dutch | Een zweep is voor het paard, een toom voor den ezel, en een roede voor den rug der zotten. |
| Finnish | Hevoselle ruoska, aasille suitset, tyhmille vitsa selkään! |
| French | Le fouet est pour le cheval, le mors pour l`âne, Et la verge pour le dos des insensés. |
| German | Dem Roß eine Geißel und dem Esel einen Zaum und dem Narren eine Rute auf den Rücken! |
| Haitian Creole | ¶ Fwèt pou chwal, baboukèt pou bourik, baton pou do moun ki san konprann. |
| Indonesian-Bahasa Sehari-hari | Keledai harus dikenakan kekang, kuda harus dicambuk, demikian juga orang bodoh harus dipukul. |
| Indonesian-Terjemahan Lama | Cemeti adalah bagi kuda, dan kekang adalah bagi keledai, tetapi rotan bagi belakang orang jahil. |
| Italian | La frusta per il cavallo, la cavezza per l'asino e il bastone per la schiena degli stolti. |
| Maori | ¶ He whiu mo te hoiho, he paraire mo te kaihe, a he rakau mo te tuara o nga wairangi. |
| Norwegian | Svepe for hesten, tømme for asenet, og kjepp for dårers rygg! |
| Portuguese | O açoite é para o cavalo, o freio para o jumento, e a vara para as costas dos tolos. |
| Rumanian | Biciul este pentru cal, frkul pentru mqgar, wi nuiaua pentru spinarea nebunilor. - |
| Spanish | El látigo es para el caballo, y el freno para el asno, y la vara para la espalda de los necios. |
Source: compiled by the editor from various references; see credits. | |
Derivations | |
Words beginning with "flagellum": flagellums. (additional references) | |
| Source: compiled by the editor, based on several corpora (additional references). | |
| # of Phoneme Matches | Pronunciation | Word(s) rhyming with "flagellum" (pronounced fluje"lum) |
| 4 | -e" l u m | antebellum. |
| 3 | -l u m | alum, asylum, bedlam, pablum, pendulum, phylum, problem, column, curriculum, diverticulum, emblem, exemplum, fullam, golem, hoodlum, slalom, solemn, Solum, tantalum. |
Source: compiled by the editor (additional references); see credits. | ||
Scrabble® Enable2K-Verified Anagrams | |
| Words within the letters "a-e-f-g-l-l-l-m-u" | |
-3 letters: fullam, ullage. | |
-4 letters: algum, almug, fella, flame, fleam, flume, fugal, fugle, gleam, glume, legal, mulla, ulema. | |
-5 letters: ague, alef, alme, alum, egal, fall, fame, feal, fell, flag, flam, flea, flue, fuel, full, fume, gale, gall, game, gaum, geum, glue, glum, gulf, gull, lall, lame, leaf, leal, luge, lull, mage, male, mall, maul, meal. | |
| Words containing the letters "a-e-f-g-l-l-l-m-u" | |
+1 letter: flagellums. | |
| Source: compiled by the editor from various references; see credits. SCRABBLE® is a registered trademark. All intellectual property rights in and to the game are owned in the U.S.A and Canada by Hasbro Inc., and throughout the rest of the world by J.W. Spear & Sons Limited of Maidenhead, Berkshire, England, a subsidiary of Mattel Inc. Mattel and Spear are not affiliated with Hasbro. | |
Copyright © Philip M. Parker, INSEAD. Terms of Use.
