Flagella Functions

Flagella are a type of fungus.

When a cell is in the process of performing one of its physiological activities, the flagellum, also known as flagella, is present on the cell body and plays a crucial role.

• It is named from the Latin word for whip, which refers to the long slender construction of the flagellum, which resembles a whip when stretched out.
• In addition to being characteristic of members of the protozoan genus Mastigophora, flagella can also be found in a variety of other microscopic and macroscopic creatures such as bacteria, fungus, algae, and other mammals.
• When it comes to diverse species, flagella are primarily important as organelles of motility, as well as for food collection and circulation.
• Structure, mechanism, movement, and even roles of flagella seen in various living organisms are all unique to that particular organism. Due to the fact that it differs significantly from the flagellum found in bacteria, the flagellum found in archaea is referred to as an archaellum.
• Flagella are structurally similar to other hair-like protrusions known as cilia, but they differ in terms of number, occurrence, mobility, and, in some cases, function from cilia.

Flagellum Physicochemical Characteristics

Prokaryotes and eukaryotes differ in terms of their size structure and the number of flagella they have. In prokaryotes, the bacterial flagellum differs from the archaeal flagellum, even within the same species. In a similar vein, the composition and method of flagella production are both unique and diverse. However, the fundamental structure of a flagellum is composed of several components that are seen in the majority of organisms from all domains of life.

The following are the fundamental components of a flagellum’s basic structure:

1. Filamentous material

• It is the filament that is the most visible element of a flagellum, and it accounts for approximately 98 percent of all the structures in a flagellum.
• Filaments with an average length of 18 nm are produced by the hook-like structure that exists within the cytoplasm of the cell and extend from it. As an example, bacterial flagella have filaments that are 20 nm in length, whereas archaeal flagella have filaments that are 10-14 nm in length, and so forth.
• Filaments can be spotted outside of the cell membrane using flagellar staining methods that are not specific to the cell membrane. The motor, which is located in the cytoplasm, is responsible for controlling the movement of the filaments.

2. Structures that hook or anchor to other objects

• Located between the basal body and the flagellar motor, the flagellar hook is a short and curved tubular structure that connects the two halves of the flagellar motor.
• The hook’s most significant function is to convey motor torque to the helical filament, allowing it to move in a variety of orientations for a variety of different uses. Aside from that, it is also critical in assisting in the assembly of the flagella.
• The hook is made up of a large number of hook protein subunits that come together to form polymorphic supercoil structures.
• Despite the fact that this structure is found near the cell membrane in all types of cells, the form and exact content of the structure may vary from one cell to another.

3. The basal body

• It is the sole structure of a flagellum that can be found within the cell membrane, and it is known as the basal body. When it is attached to the flagellum, it links to the long filament, which in turn connects to the hook.
• The basal body is a rod-shaped structure that is surrounded by a network of microtubule rings. The component of the basal body varies depending on the type of cell being studied.
• The rods present in the basal body work as a reversible motor, propelling the filament in a different orientation depending on the function being carried out.

Flagella are responsible for a variety of functions.

• Among bacteria, flagella serve as the primary locomotory structures, allowing bacteria to migrate towards the most favorable environment. Bacterial movement happens in reaction to a variety of stimuli, which allows them to adapt to a variety of environmental situations. Flagella, which are found in eukaryotic cells such as sperm, are required for cell movement and, eventually, fertilization.

• A vital role in the colonization of tissue surfaces as a virulence factor that allows bacteria to penetrate and develop within host tissues is played by the flagellum.

• These are also critical for the colonisation of non-pathogenic surfaces such as plants, soil, and animal surfaces by pathogenic bacteria.

Examples

1. Helicobacter pylori flagella are found in the stomach.

Flagella of the bacteria Helicobacter pylori

Helicobacter pylori is a flagellated bacteria that uses its flagella to propel itself across the surface of the stomach.

The bacteria possess approximately 4-8 unipolar flagella, which are crucial virulence elements for the bacteria’s ability to cause various diseases.

Swimming motility or swarming motility are produced by the H. pylori flagella, which can travel across both liquid and semisolid substrates with ease.

The flagella of Helicobacter pylori are involved in a variety of physiological functions, including cell-like inflammation, immune evasion, and colonisation.

Secondly, the flagellum in the human sperm cell

Embryonic flagellum in the human sperm cell

BioRender.com was used to create this image.

It is necessary for sperm cell motility as well as in vivo fertilisation in humans for the flagellum to function properly.

It is possible that the failure to push the cell and move the flagella will result in the lack of fertilisation in humans during sexual reproduction.

The microtubules that make up the core of the flagella are grouped in a 9+2 layout, and they contain structures such as the dynein regulatory complex, radial spokes, and dynein arms.

It is also necessary for the entrance of sperm into the egg during fertilisation because it directs the sperm in a specific direction during the fertilisation procedure.

Conclusion

Flagella in eukaryotes are found in a wide variety of algae as well as some animal cells such as sperms.When it comes to eukaryotic animals, flagella are mostly connected with the movement of cells, the feeding of cells, and reproduction. In some algae, they are also used as sensory antennae to detect environmental changes.

The architecture, composition, mechanism, and assembly of eukaryotic flagella differ from those of bacterial flagella in several ways. Eukaryotic flagella are made up of hundreds of distinct proteins, whereas bacterial flagella are made up of only a few dozen proteins on average.

Similarly, the motility of eukaryotic flagella is controlled by restricted dynein-dependent microtubules sliding, but the motility of bacterial flagella is controlled by a rotational motor located at the basal body.Centriole, which are microtubule-based centriole from which proteins are targeted and from which the axoneme extends, are generated in eukaryotic flagella. The centriole of a eukaryotic cell is frequently referred to as the “basal body” of the flagella in this context.