Name: bacterial flagella as tiny rotary motors
Uploaded: 2025-06-12T09:30:47.000Z
Duration: 1 min 18 s
Channel: JoVE

K12 Standards

Virginia  Standards of Learning

HIgh School

Biology

BIO.4

BIO.4.c

Flagella and Motility in Bacteria

Los flagelos son apéndices delgados en forma de hilo que se extienden desde la membrana plasmática y la pared celular que ayudan a las bacterias en la motilidad. El flagelo tiene tres partes principales: el filamento, el gancho y el cuerpo basal. El filamento, la parte visible del flagelo, está compuesto por subunidades de proteína flagelina dispuestas en cadenas helicoidales. Está conectado a su cuerpo basal por el gancho. El cuerpo basal consiste en una varilla central que pasa a través de una serie de anillos de proteínas. Las bacterias gramnegativas tienen cuatro anillos corporales basales. El anillo L está anclado a la capa de lipopolisacárido, el anillo P está incrustado en la capa de peptidoglicano y los anillos MS y C están unidos a la membrana plasmática y al citoplasma, respectivamente. El cuerpo basal de las bacterias Gram-positivas contiene solo los anillos MS y C. El cuerpo basal funciona como un motor impulsado por la fuerza motriz del protón, lo que permite que el flagelo gire y permita que las bacterias se impulsen a sí mismas. Además de la motilidad, los flagelos ayudan a las bacterias a adherirse a las superficies y, en algunas bacterias, contribuyen a la virulencia al ayudar en la infección.

flagelos y motilidad en bacterias

Los flagelos son estructuras especializadas en forma de filamento que se extienden desde la envoltura celular bacteriana. Desempe&#241;an un papel crucial en la motilidad y la quimiotaxis. Su organizaci&#243;n estructural y funcionamiento ejemplifican una ingenier&#237;a biol&#243;gica sofisticada, que permite a las bacterias sobrevivir y adaptarse a diversos entornos.
Estructura del flagelo
Un flagelo bacteriano consta de tres componentes clave: el filamento, el gancho y el cuerpo basal. El filamento, una estructura helicoidal alargada compuesta por subunidades repetidas de la prote&#237;na flagelina y hueca en su interior, act&#250;a como el principal elemento propulsor. El gancho conecta el filamento con el cuerpo basal, funcionando como un acoplamiento flexible que transmite el par motor a la rotaci&#243;n del filamento. El cuerpo basal constituye el anclaje del flagelo en la envoltura celular bacteriana y presenta diferencias estructurales entre bacterias gramnegativas y grampositivas. En las gramnegativas, el cuerpo basal est&#225; formado por cuatro anillos: el anillo L (anclado en la capa externa de lipopolisac&#225;ridos), el anillo P (insertado en la capa de peptidoglicano) y los anillos MS y C (ubicados en la membrana plasm&#225;tica y el citoplasma, respectivamente). Por el contrario, las bacterias grampositivas, que carecen de membrana externa y poseen una capa de peptidoglicano m&#225;s gruesa, presentan &#250;nicamente los anillos MS y C. Una varilla central conecta estos anillos, formando el n&#250;cleo del aparato motor.
Mecanismo de rotaci&#243;n y motilidad
El cuerpo basal act&#250;a como un motor rotatorio impulsado por la fuerza prot&#243;n-motriz (PMF, por sus siglas en ingl&#233;s). La PMF se genera mediante la translocaci&#243;n de protones a trav&#233;s de la membrana bacteriana, creando un gradiente electroqu&#237;mico. A medida que los protones regresan al interior celular a trav&#233;s de las prote&#237;nas motoras asociadas al cuerpo basal, la energ&#237;a liberada impulsa la rotaci&#243;n del flagelo. Esta rotaci&#243;n, que puede alcanzar varios cientos de revoluciones por segundo, impulsa a la bacteria a trav&#233;s de medios l&#237;quidos.
Papel en la quimiotaxis
Los flagelos facilitan la quimiotaxis bacteriana, un proceso que permite a las c&#233;lulas desplazarse hacia ambientes favorables o alejarse de condiciones perjudiciales. Esto se logra mediante la detecci&#243;n temporal de gradientes qu&#237;micos, con ajustes en la direcci&#243;n y frecuencia de la rotaci&#243;n flagelar. Una rotaci&#243;n en sentido antihorario da lugar a un movimiento suave y dirigido, denominado &#8220;carrera&#8221;, mientras que una rotaci&#243;n en sentido horario induce un &#8220;tropiezo&#8221;, reorientando la c&#233;lula.
La motilidad flagelar y la quimiotaxis son vitales para la supervivencia bacteriana, ya que permiten el acceso a nutrientes, la colonizaci&#243;n de entornos hospederos y la evasi&#243;n de condiciones adversas. Esta capacidad de adaptaci&#243;n pone de manifiesto la importancia evolutiva de los flagelos en la vida microbiana.

Flagelos y motilidad en bacterias

Los flagelos son estructuras especializadas en forma de filamento que se extienden desde la envoltura celular bacteriana. Desempe&#241;an un papel crucial ...

Education

Educación

JoVE Core

Microbiology

Microbiología

Unit

Unidad

Microbial Cell Structure and Function        

Estructura y función de la célula microbiana

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

bacterial flagella as tiny rotary motors

Bacterial flagella are thread-like structures that help cells move and respond to their surroundings. They extend from the cell envelope and support both motility and chemotaxis, which is the ability to move in response to chemical signals. Their design shows how bacteria use specialized structures to survive in different environments.

A flagellum has three main parts: the filament, the hook, and the basal body. The filament is the long, helical part made of repeating flagellin protein subunits, and it is hollow at the center. The hook acts as a flexible connector that passes torque from the motor to the filament.

The basal body anchors the flagellum inside the bacterial cell envelope. Its structure differs between Gram-negative and Gram-positive bacteria. Gram-negative bacteria have four rings: the L ring in the outer lipopolysaccharide layer, the P ring in the peptidoglycan layer, and the MS and C rings in the plasma membrane and cytoplasm. Gram-positive bacteria have a thicker peptidoglycan layer and no outer membrane, so they have only the MS and C rings. A central rod connects the rings and forms the core of the motor.

The basal body works as a rotary motor powered by the proton motive force, or PMF. PMF is an electrochemical gradient made by moving protons across the bacterial membrane. When protons flow back through motor proteins linked to the basal body, the released energy drives flagellar rotation. This rotation can reach several hundred revolutions per second and pushes the bacterium through liquid.

Flagella also help bacteria perform chemotaxis. Cells sense chemical gradients over time and change how often and in which direction the flagellum rotates. Counterclockwise rotation produces a smooth run, while clockwise rotation causes a tumble that reorients the cell. This movement helps bacteria reach nutrients, colonize host environments, and avoid harmful conditions.

Bacterial Flagella as Tiny Rotary Motors

prokaryotic vs. eukaryotic cells

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microbial morphologies 

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archaeal cell wall

Archaeal Cell Wall Types and Functions

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peptidoglycan synthesis

Building the Bacterial Cell Wall

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outer layers of the cell envelope

Capsules, Slime Layers, and S-Layers

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flagella and motility in bacteria

Bacterial flagella are thread-like structures that help cells move and respond to their surroundings. They extend from the cell envelope and support both motility and chemotaxis, which is the ability to move in response to chemical signals. Their design shows how bacteria use specialized structures to survive in different environments. A flagellum has three main parts: the filament, the hook, and the basal body. The filament is the long, helical part made of repeating flagellin protein...

fimbriae, pili, and axial filaments

How Bacteria Stick, Share Genes, and Move

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cell inclusions

Prokaryotic Cell Storage Inclusions

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endospores and sporulation

How Bacteria Survive with Endospores

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nucleoid

How Prokaryotes Organize DNA

Prokaryotes organize their DNA in the nucleoid, a distinct region where genetic material and associated proteins are packed. Because prokaryotic cells do not have a membrane-bound nucleus, the nucleoid helps keep DNA organized and available for cell activities. In most bacteria and archaea, the DNA is a single, circular, double-stranded molecule that is tightly compacted by supercoiling and protein interactions. Nucleoid-associated proteins, or NAPs, help shape and maintain this DNA region.

surface appendages of archaea

Archaeal Pili and Archaella in Action

Archaeal pili and archaella help archaea survive, attach, and move in challenging environments. These surface appendages support adhesion, biofilm formation, and motility. They give archaeal cells key advantages in habitats that can be extreme. Pili are filament-like structures made from pilin protein subunits. Their main role is adhesion, which means helping cells stick to surfaces. They also support biofilm formation, where cells live in a shared, surface-attached community. Some pili are...

key terms and concepts

Learn how bacterial flagella work as rotary motors, how Gram-negative and Gram-positive cells differ, and how runs and tumbles guide chemotaxis.

Bacterial Flagella as Tiny Rotary Motors | JoVE K12

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Bacterial Flagella as Tiny Rotary Motors

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