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Difference Between Cilia and Flagella

Cilia-and-Flagella

Cilia and flagella are the two cytoplasmic cells extending from the cell’s surface. The two cells have various differences due to their structure, size, numbers, and functioning. Cilia are relatively shorter in size and can only be seen via a microscope, whereas Flagella are a large complex structure.

Cilia and Flagella’s primary function is mainly associated with locomotion, but it also helps in other processes such as circulation and respiration. They are found in the cell’s surface extending from the plasma and are usually found in Eukaryotic and Prokaryotic cells.

Definition of Cilia

Cilia are microscopic structures that are short and hair-like. It extends from the surface of a living cell in single or multiple units. Cilia are responsible for moving the entire cells along the outer surface of the cells.

Almost all the eukaryotic cells comprise cilia, which plays a crucial part in the cell and the body’s development. They are usually found in paramecium organisms in hundreds of quantities on the surface of the cells.

Cilia can be found chiefly active during cell cycle development and progression. It, however, allows only specific proteins for proper functioning. It also plays a vital part in molecular trafficking and cellular communication and participates in the vesicular secretion of ectosomes.

The length of cilia varies from 1-10 µm, whereas its width is less than 1 µm. Cilia are broadly divided into two main types:

  • Motile
  • Non-Motile

Motile cilia are found in the respiratory tract, lungs, and middle ear of the human body. It is the moving cilia that prevent mucus and dust along the airways along with facilitating the movement of sperms. This type of cilia is responsible for easy breathing and assures smooth functioning of the respiratory tract.

Motile cilia have a 9+2 arrangement. In this arrangement, nine fused microtubules form a circle, whereas the two unfused microtubules are present in the circle’s centre.

Non-motile cilia work as an antenna for the cells as it is capable of receiving signals from other cells. Non-motile cilia, also known as primary cilia, have a 9+0 arrangement in which nine fused microtubules forms a circle.

Definition of Flagella

Flagella are hair-like structures that are long and complex and are present on the surface of the cell, extending from the plasma membrane. The main function of Flagella in a body is to move an entire cell from one place to another.

Flagella consists of a hook in the cell envelope, a filament that is the external part of the cell, and a basal body attached to the cytoplasmic membrane.

Flagella are made up of flagellin protein fixed in a cell envelope and are 150µ long and 0.02 to 0.025µm thin. Flagella are categorized into three types:

  • Bacterial flagella
  • Archaeal flagella
  • Eukaryotic flagella

Bacterial flagella have a helical filamentous structure rotating like screws. They are typically found in Salmonella typhi, E. coli. This type of flagella is responsible for the motility of bacteria. The motion is in rotatory movement in prokaryotes. Bacterial flagella can be single or many per cell.

Archaeal flagella comprise of similar properties and characteristics as that of bacterial flagella with only difference in the lack of central channel. This type of flagella is also responsible for motility and is present as single or many per cells.

Eukaryotic flagella are a complex type of flagella that has difficult projections. This type of flagella beats back and forth, which means that the flagella return to their original position multiple times.

Difference Between Cilia and Flagella

CharacterCiliaFlagella
StructureShort and hair-like structureLong and complex hair-like structure
Length1-10 µm150µ
Width1 µm0.02 to 0.025µm thin
PresenceIn Eukaryotic cellIn Eukaryotic as well as Prokaryotic cells
PositionThe surface of the cellThe surface of the cell extending from the plasma membrane
MotilityRotational and fast-movingRotatory movement
FunctionLocomotion and circulationLocomotion only
CategoryTwo typesThree types
NumbersNumerousLess in number
DensityHundreds per cellLess than 10 per cell

Similarities

Cilia and Flagella shares some similarities as well, such as:

  • Both outgrow the plasma of the cell.
  • Arise from the basal body
  • They consist of an axoneme which is a central filament.
  • Both have a 9+2 arrangement
  • Both help in locomotion

Conclusion

Cilia and Flagella are found in Eukaryotes and Prokaryotes. The cells have a similar structure and only differ in numbers. The cells mainly perform the function of locomotion but, in some cases, helps in respiration, circulation, and excretion.

 The cells also differ in their way of motion as cilia rotate while flagella have rotary movement. The difference is wider due to the different ways of functioning and moving by the two cells. Overall, Cilia comprises a simple structure, whereas the structure of flagella is complex, which is a key in differentiating the two cells and their way of functioning.

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