Flagella: Definition, Structure and Types

The cytoskeleton is a redesigned fibrous proteinaceous framework found in the cytoplasm of the cell. It provides mechanical support to cells. It also assists the cell in maintaining its own form and movement.

Microtubules are also called tubulin polymers and are larger than the other two. Their diameter is around 25 nanometers. The main function of this fiber is to preserve the shape of cells. It also aids with cell mobility, for instance, the motion of the chromosomes during cell division. The cilia and flagella of eukaryotic cells are composed of microtubules.

Definition

Flagella are hair-like protrusions from the cell membrane. They are larger compared to the cilia and cause cell movement through whiplash-like movement. The singular form of flagella is the flagellum.

Structure of flagella

1. Flagella are longer than cilia, measuring about 15 µm for flagella compared to cilia which are 5 µm to 10 µm in diameter.
2. Each cell structure usually has 1 to 2 flagella.
3. The structure of bacterial flagella is different from the eukaryotes. The bacterial flagellum is made up of protein subunits of flagellin.
4. They are membrane-bound and protrude protoplasmically.
5. An electron microscope examination reveals that it is surrounded by a plasma membrane.
6. Flagella are mainly composed of microtubules of the contractile protein tubulin.
7. Multiple microtubules make up the flagella’s core.
8. Lengthways, these microtubules extend. The axoneme is the name for the core.
9. There are nine pairs of peripheral microtubule doublets organized radially in the axoneme.
10. In the center, there are two (a pair of) microtubules.
11. The microtubules are arranged in a 9 + 2 pattern, with two central microtubules and nine duplet sets around them.

Flagella Types

There are four unique kinds of flagella:

1. Monotrichous flagella: A solitary flagellum that lies at one end or the other. These are called the polar flagellum. They can move clockwise or anti-clockwise. The clockwise movement moves the microorganism forward, and also the anti-clockwise motion reverses it.
2. Peritrichous flagella: A number of flagella are connected to the organism. They aren’t Polar flagella as they are around the organism. The flagella rotates anti-clockwise and produces a package that has the ability to relocate the organism in a single instruction. If several flagella break and begin rotating clockwise, the body does have no movement in the direction it is in and begins to roll.
3. Lophotrichous flagella: A variety of flagella at one end of the microorganism, or on the contrary. They are described as Polar flagellum, and they can transform clockwise or anti-clockwise. The clockwise movement pushes the microorganism ahead, while the anti-clockwise activity is pulling it backward.
4. Amphitrichous flagella: Solitary flagellum at both ends of the microorganism is known as polar flagellum. They can move clockwise or counterclockwise. The clockwise movement presses the organism ahead, while the anti-clockwise movement reverses it.

Flagella Feature

Flagella satisfies the complying with tasks:

1. Flagella are used by some unicellular organisms, such as Euglena, to swim in the water.
2. They assist microorganism relocation.
3. They are sensing units to identify changes in pH and also temperature.
4. Just a few eukaryotes use flagellum in order to increase the rate of reproduction.
5. Current research studies have actually revealed flagella also serve as organelles for secretion. For example;chlamydomonas.