Flagella are microscopic hair-like structured organisms that help in the movement of a cell and are mostly unicellular. Flagella actually means “whip” because of its whip-like appearance that helps to propel a cell through fluids. In this article on flagella, students will learn about the basics of flagella, the functions, and the structure as well as types of flagella.
A flagellum has a 15-20nm diameter and can be seen under a light microscope. The whip-like structure of flagella facilitates movement in certain single-celled organisms. These are filamentous structures made up of microtubules. They are usually found in eukaryotes and bacteria.
There are 6 types of flagella:
Atrichous: There is no flagellum.
Single polar flagellum can rotate both clocks and anti-clockwise resulting in forwarding movement and backward movement respectively.
Example: Vibrio cholerae
One flagellum is present on each end. Movements are like monotrichous flagella.
Example: Alkaligens faecalis
Tufts of flagella present at one or both sides. Propagates clockwise and anticlockwise.
Numerous flagella are present all over the bacterial body, anticlockwise rotation produces one-directional movement.
Example: Salmonella Typhi
Cephalotrichous: several flagella are present at both ends. Movements are similar to monotrichous flagella.
The flagella are helical in structure and composed of flagellin protein or globular protein. The body of flagella is divided into three parts:
The basal body consists of a rod and a series of rings that are attached to the cell wall and the cytoplasmic membrane. It consists of rings which are basically proteins. There are three types of rings, namely the L-ring attached to the lipopolysaccharide, the P-ring attached to the peptidoglycan layer, and the M-S ring which is attached to the cytoplasmic membrane.
The hook is a flexible connection between the filament and the basal body proteins.
The filament is a rigid, helical structure that extends from the cell surface. It has a hair-like structure.
A flagellum also has some functions in eukaryotes and bacteria alike. They can be stated as follows:
Flagella facilitates movement and locomotion in organisms.
Flagella can help detect changes in pH and temperature
They help eukaryotes to enhance their reproductive rates, they are present in the uterus of human females.
They help in the identification of certain types of organisms.
1. What is the Role of Flagella in a Bacterial Cell?
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.
2. Where is Flagella Found?
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.
3. What are the Types of Flagellation?
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.
4. What are flagella?
Flagella are hair-like structures that primarily help in the locomotion of living organisms. Flagella is the characteristic feature of the protozoan group Mastigophora, it also occurs in gametes of algae, fungi, mosses, and animals. Most mobile bacteria move with the help of flagella.
5. How are flagella different from cilia?
The difference between flagella and cilia are as follows:
Cilia are short, hair-like structures whereas flagella are long, threadlike structures present on the surface of a living cell.
Cilia are found in Eukaryotic cells. Flagella are found in both prokaryotic cells as well as in eukaryotic cells.
Cilia are present throughout the surface of the cell. Flagella is present at both the ends or all over the surface.
Cilia help in locomotion, aeration, feeding circulation, etc. Flagella helps mainly in locomotion only.
Cilia are present in many (hundreds) per cell. Flagella is present in a few (less than 10) per cell
6. What are the functions of flagella?
The functions of flagella are given as follows;
In bacteria, it helps with motility. In eukaryotes, flagella is present in sperm which help in locomotion and eventually fertilization. Flagella plays an important role in colonization on tissue surface as a virulence factor to invade host tissue.
Helicobacter pylori use its flagella for its propulsion through the tissue surface.
7. What are the six types of flagella?
There are six types of flagella: Atrichous, Monotrichous, Amphitrichous, Lophotrichous, Peritrichous and Cephalotrichous.
8. What are the parts of flagella?
A flagellum has a helical structure and is divided into three parts: basal body, hook, and filament.
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