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Topic: Flagellum

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  Flagella - EvoWiki   (Site not responding. Last check: 2007-10-14)
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).
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)).
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.
wiki.cotch.net /index.php/Flagellum   (1119 words)

The components of the flagellum are capable of self-assembly in which the component proteins associate spontaneously without the aid of enzymes or other factors.
The archaeal flagellum is superficially similar to the bacterial flagellum; in the 1980s they were thought to be homologous on the basis of gross morphology and behavior.
A eukaryotic flagellum is a bundle of nine fused pairs of microtubules doublets surrounding two central single microtubules.
www.daviddarling.info /encyclopedia/F/flagellum.html   (1213 words)

 Flagellum - Wikipedia, the free encyclopedia
A eukaryotic flagellum is a bundle of nine fused pairs of microtubule doublets surrounding two central single microtubules.
At the base of a eukaryotic flagellum is a basal body, "blepharoplast" or kinetosome, which is the microtubule organizing center for flagellar microtubules and is about 500 nanometers long.
The flagellum is encased within the cell's plasma membrane, so that the interior of the flagellum is accessible to the cell's cytoplasm.
en.wikipedia.org /wiki/Flagellum   (1430 words)

 Access Research Network in the WindowView
The flagellum is a long, hairlike filament embedded in the cell membrane.
The external filament consists of a single type of protein, called "flagellin." The flagellin filament is the paddle surface that contacts the the liquid during swimming.
At the end of the flagellin filament near the surface of the cell, there is a bulge in the thickness of the flagellum.
www.windowview.org /science/arn.files/flagellum.html   (580 words)

 ARN Molecular Museum: The Bacterial Flagellum as an example of Irreducible Complexity
Because the bacterial flagellum is necessarily composed of at least three parts -- a paddle,a rotor, and a motor -- it is irreducibly complex.
The structure of a flagellum is quite different from that of a cilium.
The flagellum is a long, hairlike filament embedded in the cell membrane.
www.arn.org /docs/mm/flagellum_all.htm   (611 words)

 Metanexus Institute
The Bacterial Flagellum: A Response to Ursula Goodenough
She insists that the primal flagellum was, indeed, functional, which suggests that the primal flagellum somehow was already managing to perform all the required functions for flagellar motility, without the contribution of protein #18 (which we assume was lacking to start with).
The problem is that the proteins which are to become the flagellum are coming from systems that are distinctly non-flagellar in nature (after all, we are discussing the origin of that very system) and being co-modified from their original molecular interactions into an entirely new set of molecular interactions.
metanexus.net /metanexus_online/show_article.asp?7790   (4495 words)

Accordingly, the TTSS may be thought of as a possible subsystem of the flagellum that performs a function distinct from the flagellum.
Miller's appeal to the TTSS as a precursor on an indirect Darwinian pathway to the bacterial flagellum is a case in point.
As John Bracht (2003) points out: "The problem is that the proteins which are to become the flagellum are coming from systems that are distinctly non-flagellar in nature (after all, we are discussing the origin of that very system) and being co-modified from their original molecular interactions into an entirely new set of molecular interactions.
www.designinference.com /documents/2003.02.Miller_Response.htm   (6838 words)

 The Flagellum Unspun
The flagellum is an ion-powered rotary motor, anchored in the membranes surrounding the bacterial cell.
The great irony of the flagellum's increasing acceptance as an icon of anti-evolution is that fact that research had demolished its status as an example of irreducible complexity almost at the very moment it was first proclaimed.
When anti-evolutionary arguments featuring the bacterial flagellum rose into prominence, beginning with the 1996 publication of Darwin's Black Box (Behe 1996a), they were predicated upon the assertion that each of the protein components of the flagellum were crafted, in a single act of design, to fit the specific purpose of the flagellum.
www.millerandlevine.com /km/evol/design2/article.html   (6610 words)

 Evolving the Bacterial Flagellum Through Cooption
The bacterial flagellum is a motility structure whose irreducible and specified complexity has been cited as evidence for its design (a good basic description can be found here).
The bacterial flagellum is quite unlike the eukaryotic flagellum in this regard, as the latter is in direct communication with the cytoplasm and bounded by the plasma membrane.
The bacterial flagellum, in contrast, penetrates the cell membrane and wall and is housed outside of the cell membrane.
www.idthink.net /biot/flag1   (3286 words)

 Protein Targeting of an Unusual, Evolutionarily Conserved Adenylate Kinase to a Eukaryotic Flagellum -- Pullen et al. ...   (Site not responding. Last check: 2007-10-14)
Transmission electron micrograph of thin sections through the flagellum show the wild-type organization of the axoneme and PFR in the noninduced snl-2 mutant (A) and the absence of the PFR in paralyzed, induced snl-2 (B).
The immunofluorescence pattern indicates that ADKA is present from the point where the flagellum leaves the cell body (white arrow) to its distal tip, but not at the point where the axoneme is nucleated from the basal body that is attached to the mitochondrial genome (fl arrow; Ogbadoyi et al., 2003
Pullen, T.J. A proteomic investigation of the trypanosome flagellum.
www.molbiolcell.org /cgi/content/full/15/7/3257   (5467 words)

 CB200.1: Bacterial flagella and Irreducibly Complexity
Many of the proteins in the bacterial flagellum or eukaryotic cilium are similar to each other or to proteins for other functions.
Homologs of the motor proteins MotA and MotB are known to function in diverse prokaryotes independent of the flagellum.
The eukaryotic cilium (also called the eukaryotic flagellum or undulipodium) is fundamentally different from the bacterial flagellum.
www.talkorigins.org /indexcc/CB/CB200_1.html   (898 words)

 Moving forward: The trypanosome flagellum
But that is not the only string to the flagellum's bow: it also acts as an anchor and has a central role in cell division.
As well as being important in motility, the trypanosome flagellum is used by the parasite to attach itself to the tsetse salivary gland – without this, it would be quickly washed out.
He has recently found that as the cell divides, the new flagellum emerges from the cell and is guided down the helix of the old flagellum by a structure he calls the flagellar connector.
www.wellcome.ac.uk /doc_WTX026059.html   (2004 words)

 The Evolution of the Flagellum
Consider that the bacterial flagellum is found in both mesophilic, thermophilic, gram-positive, gram-negative, and spirochete bacteria while TTSS systems are restricted to a few gram-negative bacteria.
Further duplications of the proto-rod, filament, and cap proteins, occurring before and after the origin of the flagellum (6) produce the rest of the axial proteins; these repeated subfunctionalization events are not shown here.
The building of a hollow flagellum where the flagellum is formed by adding monomers to the distal tip is extraordinarily complicated.
www.detectingdesign.com /flagellum.html   (9046 words)

 The Alternative Sigma Factor AlgT Represses Pseudomonas aeruginosa Flagellum Biosynthesis by Inhibiting Expression of ...   (Site not responding. Last check: 2007-10-14)
We hypothesized that in CF isolates, the alginate phenotype and
AlgT mediates the negative regulation of flagellum biosynthesis in mucoid, nonmotile CF isolates.
This is similar to the shutoff of flagellum synthesis in E.
jb.asm.org /cgi/content/full/187/23/7955   (5345 words)

 The flagella connector of Trypanosoma brucei: an unusual mobile transmembrane junction -- Briggs et al. 117 (9): 1641 ...   (Site not responding. Last check: 2007-10-14)
The new flagellum (nf) is always observed to the left of the old flagellum (of) when viewed from the posterior end of the cell.
The tip of the new flagellum is associated with the lateral aspect of the old flagellum, via the flagella connector, indicated by the white arrow.
The tip of the new flagellum (nf) is close to the old flagellum (of) but a physical connection is not observed.
jcs.biologists.org /cgi/content/full/117/9/1641   (6633 words)

 Reader background for flagellum evolution article   (Site not responding. Last check: 2007-10-14)
The article "Evolution in (Brownian) space: a model for the origin of the bacterial flagellum" is an attempt to put forward a reasonably detailed model for the evolutionary origin of the bacterial flagellum.
The bacterial flagellum was only discussed briefly in Behe's Darwin's Black Box, but perhaps because of the counterarguments and literature available on the evolution of other systems, the bacterial flagellum soon became the favorite example of irreducible complexity, and has ascended to near-iconic status for the ID movement.
The Bacterial Flagellum: A Response to Ursula Goodenough (2002)
www.talkdesign.org /faqs/flagellum_background.html   (1168 words)

 The Panda's Thumb: Flagellum evolution in Nature Reviews Microbiology   (Site not responding. Last check: 2007-10-14)
ID advocates say that their position is supported by discontinuities between the flagellum and the rest of the biological world, just as a designed entity like a watch differs from an undesigned entity, such as a stone.
Scott Minnich, the leading flagellum expert in the ID camp, was severely wrong about the most basic data relevant to the origins of the flagellum, the flagship system of the ID movement.
on a supposed evolutionary pathway for the bacterial flagellum.
www.pandasthumb.org /archives/2006/09/flagellum_evolu.html   (9172 words)

 Intelligent Design Topic: Is the flagellum specified?
For instance, in the case of the bacterial flagellum, humans developed outboard rotary motors well before they figured out that the flagellum was such a machine.”
But the pattern itself would never be recognized unless it were first provided the appropriate environmental context and allowed to express itself in the formation of a flagellar appendage to a bacterial cell.
The base-pair sequence pattern in question is not detachable, and the flagellum is not specified in the particular sense required by Dembski’s complexity-specification criterion.
www.counterbalance.net /id-hvt/isthe2-body.html   (1113 words)

 Physics Today On The Web - Cover Story
The flagellum is an organelle that has three parts (as figure 2 shows).
There is a basal body consisting of a reversible rotary motor embedded in the cell wall, beginning within the cytoplasm and ending at the outer membrane.
The flagellum is assembled from the inside out, with the axial components exported through a central channel.
www.aip.org /pt/jan00/berg.htm   (4402 words)

 Playing with flagellum - Minnesota Daily   (Site not responding. Last check: 2007-10-14)
The fact that genetic disruption of any member of this large set of proteins abolishes or greatly impairs swimming behavior suggests to proponents of intelligent design that the flagellum is irreducibly complex and that evolutionary models cannot account for the emergence of such a structure by stepwise modification of existing structures with different functions.
One plausible scenario for the origin of the primitive flagellum postulates the cooptation of a gene that codes for an enzyme that normally functions to provide energy to the cell.
Musgrave, I. "Evolution of the Bacterial Flagellum," in Young, M and Edis, T. (Eds) "Why Intelligent Design Fails: A Scientific Critique of Neocreationism." Rutgers University Press, Piscataway, N.J. Martin Dworkin and Gary Dunny are University professors of microbiology.
www.mndaily.com /articles/2006/01/25/66781   (997 words)

 Flagellum Evolution | Uncommon Descent
The flagellum on the other hand is for locomotion, not parasitic or pathogenic relationships with more complex cells.
The flagellum is useful absent more complex organisms in the environment while the ttss is not.
It’s not as though the flagellum is the cornerstone of all life on earth.
www.uncommondescent.com /index.php/archives/1563   (12232 words)

 Evolution of the bacterial flagellum   (Site not responding. Last check: 2007-10-14)
Thirdly, the question of which proteins are actually universally “essential” for flagellum function, and which proteins have homology to other flagellar proteins or nonflagellar proteins, has been systematically reviewed in Table 1 of Pallen and Matzke (2006).
This is substantially more impressive than the situation in 2003, and means that the evidence for the evolutionary origin of the flagellum by standard gene duplication and cooption processes is even stronger than in 2003.
ATP synthetase and the flagellum is further suggested by homology between the flagellar ATPase FliI and the β subunit of F
www.talkdesign.org /faqs/flagellum.html   (8497 words)

 Evolution News & Views: Do Car Engines Run on Lugnuts? A Response to Ken Miller & Judge Jones's Straw Tests of ...
Judge Jones ruled that the irreducible complexity of the bacterial flagellum, as argued by intelligent design proponents during the trial, was refuted by the testimony of the plaintiffs’ expert biology witness, Dr. Kenneth Miller.
The bacterial flagellum is a motor-driven propeller for bacterial swimming.
For example in the case of the bacterial flagellum, removal of a part may prevent it from acting as a rotary motor.
www.evolutionnews.org /2006/04/do_car_engines_run_on_lugnuts.html   (1978 words)

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