Structure and Function of Flagella in Bacteria
Bacteria can swim to move around in their natural environment and locate other sources of food. One way that bacteria do this is by using a flagellum, which is a long, thin fiber that protrudes from the cell.
Flagella in Bacteria
The flagellum is always composed of one or more bundles of filaments, which take the place of a nucleus in prokaryotic cells. The end of the filament is called a flagellar base, and it has several hook-like proteins that will attach to proteins on the surface of the cell.
The flagellum spins rapidly, transporting the cell forward, much in the same way that a propeller attached to a boat can make it move across the surface of the water. Bacteria can move in any direction by reversing the direction that their flagella spin.
Structure of Flagella in Bacteria
A bacterial cell usually has multiple flagella, and each one will propel it in a different direction. The flagella are attached to the cell through a protein called an H-protein; this protein is highly conserved among different types of bacteria yet is variable between species and even between individual strains of bacteria.
The proteins on the end of the flagellum are conserved, but not all of them were originally present on the flagellum. When new proteins are added to the end of a flagellum, they may copy one or more traits from their neighbors that already contain that particular trait
. Using the evolution methods, one or more traits can be altered over time to create brand new proteins that would not have been possible when the original flagellum was first created. This process is known as convergent evolution, and it has led to the creation of many different types of flagella, which are all also able to perform various functions.
Bacterial flagella have a number of distinct structural components. The central core that contains the axial channel and the hook proteins are called the basal body or flagellar basal body. There is always a single propeller-like structure at one end of the flagellum, and this is called the hook.
The hook sticks out of the cell and has a number of different proteins that are responsible for attaching it to other proteins on the surface of the flagellum, which keeps it from coming loose. These proteins are called flagellar basal body proteins or FBPs.
The flagellum’s central channel is called the axial channel, and its shape determines the overall shape of the flagellum. The axial channel can be spiral, which allows it to spin around a single point and is capable of moving in any direction.
An axial channel that is corkscrew-like in shape allows for motion in one direction, such as moving to the left or right. An axial channel that is pentagonal in shape will only allow the flagellum to spin in one direction, which is determined by its opening.
A bacterial flagellum structure is composed of many different proteins, and these proteins are coded for by genes. The genes associated with the flagellum will not always code for all of the different components that make up a complete bacterial flagellum. Still, they will often code for a portion of it, which can then be assembled into its final form.
Only the end of a flagellum is made up of proteins that were present at the beginning, while the rest of the structure was assembled by utilizing proteins from neighboring flagella.
Types of Flagella in Bacteria
There are various different types of bacterial flagella based on their appearance. The types that do not have any additional structures or parts are called monotrichous flagella; these consist solely of a filament and do not have any additional components.
Examples of bacterial flagella arrangement schemes: (A) monotrichous; (B) lophotrichous; (C) amphitrichous; (D) peritrichous.
There are various types of monotrichous flagella that have varying shapes, including types that look like needles or pili. Numerous types of monotrichous flagella do not look like thin filaments at all and can be straight rod-like structures, ring-like structures, or even crescent-shaped structures.
There are a large number of bacteria that contain more than one flagellum. A bacterium with multiple flagella is called a “peritrichous” bacterium. The most common types of peritrichous bacteria are Bacillus and “Escherichia coli.” It is sometimes hard to tell which bacteria are monotrichous and which ones have multiple flagella, but for a large number of bacteria, the flagella are used in the same way and have the same function.
This makes it easy to tell whether or not they are monotrichous or peritrichous. Two types of peritrichous bacteria have flagella that serve particular functions. These are the type of bacteria that use their flagella in motility and the type of bacteria that uses their flagellum in differentiation. A single bacterium can have both types of flagella on it at the same time.
The type of bacterial flagellum with the most parts is called “lophotrichous.” The lophotrichous flagella have multiple components and different colored bands that distinguish the different parts. This is more complex than a monotrichous flagellum and, as such, has a specific function.
The lophotrichous bacteria are able to move through different types of environments, such as very hot or very cold environments, without being disturbed by these changes in temperature. Beaming in “Escherichia coli” is an example of this type of behavior. In order for the bacteria to sense the environment, it needs to move in; it must have a flagellum that allows it to sense the presence of light. This type of flagellum is called a lophotrichous flagellum.
The “flagellar protein” present on the bacterial flagellum is made up of smaller parts that are broken down into their individual components by proteases after they are first assembled. These small soluble proteins that make up the flagellum are called proteins that are “flagellar.”
The molecules of these flagellar proteins can be altered by proteases. Proteases trigger changes in the flagellar protein-making some parts of the protein larger and some other parts smaller. This results in different shapes, sizes, and lengths, which determine the function of the proteins.
There are a variety of different types of proteases that can alter the proteins in different ways, such as by cleaving the protein at different points. There are also a variety of proteins that are known to inhibit proteases in order to create a stable flagellar structure
. This means that there is a variety of things that can alter the structure of the flagella and cause them to be formed in different ways according to what bacteria need for their specific environment or functions.
The flagellar protein is not all that is needed for a bacterium to have functional flagella. It was shown by experiments that even though the flagellar protein might be in the cell, it will not form into functional flagella if there is no structure to support it.
The structure that supports the formation of the flagella is called an “architectural-transitional complex.” The complex is made up of several different proteins that create the structure for the flagellar assembly.
An asymmetrical rotor is a type of rotary engine with a unique design that produces motion in one direction without varying speed, regardless of any movement from the outside or inside source. Its simplest form (a helically-wound rotor) consists of a uniform disk with a hole in the center and a shaft passing through it.
The axis of the shaft is in line with the central hole through the disk. The rotor is placed inside a housing; such a housing may be any symmetric, non-rotating, non-ferrous object (e.g., an iron block).
The rotor is spun either by hand or by attaching it to a motor. In either case, the spinning rotor forms a centripetal force that holds it in place within its housing. The shape of the housing directs force outward along radial lines, away from its center.
The motion of the rotor is non-reciprocating; that is, it both spins and moves forward. The outer housing should be balanced so that there is no noticeable vibration.
The asymmetrical rotor consists of a disk or any other object (even a ball or ring) with a hole in its center and a shaft going through it. The disk can be made from any material, but the centrifugal force should not exceed the strength of the material being used because if it does, then the disk will break or crack.