Structure of flagella

Flagella are minute hair-like structures that assist in cell motility and are generally unicellular. Flagella is named because its whip-like appearance, which aids in propelling a cell through fluids. Students will learn about the basics of flagella, their functions, and structure, as well as the several varieties of flagella, in this article on flagella. 

Flagella:

Under a light microscope, a flagellum has a diameter of 15-20nm and can be seen. Flagella has a whip-like structure that aids mobility in single-celled organisms. These are microtubule-based filamentous formations. Eukaryotes and bacteria are the most common hosts. 

Types of flagella:

Flagella are of 6 types:

1. Atrichous: There isn’t a flagellum to be found. Lactobacillus, for example. 
2. Monotrichous: A single polar flagellum can revolve both clockwise and counterclockwise, allowing for forward and backward movement. Vibrio cholerae, for example. 
3. Amphitrichous: On each end, one flagellum is present. Movements function similarly to monotrichous flagella. Alkaligens faecalis, for example. 
4. Lophotrichous: Flagella tufts can be found on one or both sides. It spreads both clockwise and counterclockwise. Spirillum is a good example. 
5. Peritrichous: The bacterial body is covered in flagella, which rotate anticlockwise to provide one-directional locomotion. Salmonella Typhi, for example. 
6. Cephalotrichous: At both ends, there are numerous flagella. Monotrichous flagella have identical movements. Pseudomonas aeruginosa is an example of a bacterium. 

Structure of flagella:

Flagella have a helical structure and are made up of flagellin or globular proteins. Flagella’s body is separated into three sections: 

1. Basal body
2. Hook
3. Filament

A rod and a series of rings linked to the cell wall and cytoplasmic membrane make up the basal body. It is made up of rings, which are essentially proteins. The hook is a flexible link between the filament and the proteins of the basal body. The filament is a helical, hard structure that stretches from the surface of the cell. It has a hairy appearance. 

Functions of flagella:

1. In organisms, flagella aids movement and motility.
2. Flagella can assist detect pH and temperature changes. 
3. They aid eukaryotes in increasing their reproduction rates and are found in the uterus of female humans. 
4. They aid in the identification of specific species. 

Cilia:

All mammalian cells have cilia, which are tiny, slender hair-like projections on their surfaces. They are primitive in character and can be solitary or in groups. Cilia are important for movement. They have a role in mechanoreception as well. Ciliates are organisms that have cilia on their skin. Their cilia are used for feeding and movement. 

Types of cilia:

There are 2 types of cilia:

1. Motile cilia:

These can be found in huge quantities on the cell’s surface. These are found in the respiratory epithelium of humans’ respiratory tracts. They do their job by removing mucus and particles from the lungs. 

1. Non-motile cilia:

Primary Cilia were initially found in 1898 and are non-motile cilia. For a long time, these structures were thought to be vestigial organelles. Recent studies have revealed that primary cilia serve as a sensory cellular antenna that coordinates a vast number of cellular signalling pathways. 

Structure of cilia:

Microtubules covered by the plasma membrane make up cilia. Each cilium has nine pairs of microtubules on the outside ring and two microtubules in the centre. An axoneme is the name for this structure. The nine outer pairs are made up of dynein motor proteins. The cilia can move because these are big and flexible. 

Function of cilia:

Cilia are involved in movement and sensory processes, among other things. They are important in the cell cycle and replication, as well as in human and animal development. Multiple cilia move in a rhythmic pace to keep mucus and foreign agents out of the interior pathways. 

A few non-motile cilia serve as an antenna, receiving sensory information from the surrounding fluids and processing it for the cells. The cilia in the kidney, for example, bend violently when the urine passes. This alerts the cells to the fact that urine is flowing. 

Conclusion:

The motile cellular appendages cilia and flagella are found in most microbes and animals, but not in higher plants. Cilia enable multicellular animals move cells or groups of cells, as well as convey fluids and materials past them. Cilia and flagella in eukaryotic cells contain the motor protein dynein, as well as microtubules, which are linear polymers of globular proteins called tubulin.