The flagellum is one of the most crucial entities in most unicellular organisms.
The flagellum is one of the most crucial entities in most unicellular organisms. Its presence helps such organisms in more than one way. All of these make it vital for us to learn more about its fundamental aspects to become familiar with its functioning. With that being said, let’s quickly go through the basics of flagella including – flagella structure and its function in brief. What is Flagella? Flagella are whip-like structures which facilitate movement in specific unicellular organisms. They help cells and organisms to move linearly. These filamentous structures are made up of microtubules. They are found in bacteria, archaea and eukaryotes. A flagellum is usually 15-20nm in diameter. After staining with a clear stain, it can be seen under a light microscope. Typically, the staining process helps to increase its diameter. Flagella Structure Essentially, a flagellum is helical in structure and is composed of flagellin protein or globular protein. There are three distinct parts of flagellum –
It is located outside the cell and arises from the hook. It has a structure that resembles thin hair.
It is the broader region situated at the filament’s base. It is relatively longer in Gram +ve bacteria when compared to gram –ve bacteria. Also, it serves as a connector of filament and motor protein that is present in the base.
This part is attached to the cytoplasmic and cell membrane, consisting of rings which are surrounded by Mot (a pair of proteins). These following rings are present in this part –
Check out this figure below to gain a more distinct idea of the structure of a bacterial flagellum. [Image will be Uploaded Soon] DIY: Draw a diagram of bacterial flagella and label its parts accurately. Types of Flagella Flagella are of 6 types. These are listed below.
There is no flagellum in organisms. Lactobacillus and Pasteurella are well-suited examples.
It has a single flagellum on end, which is known as a polar flagellum. It can rotate both clockwise and anti-clockwise. Its clockwise movement helps organisms to move forward, whereas its anti-clockwise movement draws organisms back. Vibrio cholera is an example of Monotrichous.
There is one flagellum at each end, which is known as a polar flagellum. It can rotate both clockwise and anti-clockwise. The movement is the same as that in Monotrichous.
Several flagella are present overall. Peritrichous rotates anti-clockwise and aids organisms to move towards one direction. These are also characteristic as the organism cannot move towards any direction or may also tumble if a few flagella break. It may begin to rotate clockwise instead. E. coli is an example of Peritrichous.
Several flagellums at any of the two ends or both ends are also known as polar flagella. It can also rotate in the clockwise and anti-clockwise direction, wherein the former movement propels an organism forward and the latter draws them back. Spirillum is a suitable example of Lophotrichous.
Several flagella are present at both ends of organisms. Both movement and method of locomotion is similar to other polar flagella. Pseudomonas is a suitable example. This figure shows the accurate flagella diagram. [Image will be Uploaded Soon] Function of Flagella In case you are wondering what do flagellum do, these following will absolve your query –
Test Your Knowledge: The primary flagella function is:
Flagella versus Cilia This figure highlights the fundamental difference between flagella and cilia [Image will be Uploaded Soon]
Ans. Flagellum helps organisms to move and to detect changes in temperature and pH level. It further helps to identify certain organisms quickly. Also, it accelerates the rate of reproduction in eukaryotes.
Ans. Flagella is located at the back of a unicellular organism or cell body. A flagellum has a tail-like appearance, and it is primarily responsible for locomotion in organisms.
Ans. There are 6 types of bacterial flagellation – i. Atrichous ii. Monotrichous iii. Amphitrichous iv. Cephalotrichous v. Lophotrichous vi. Peritrichous. Notably, each of them has a distinct structure that sets them apart.
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