Flagella

A flagellum is a cage-like structure that is involved in the locomotion of a cell. It is grouped into the class of protozoan. The key role of a flagellum is locomotion and also functions as an organelle. They exist in all three domain of this living world. For example fungi, protists, animals, and plants, eukaryote, bacteria. There are different kinds of flagella that are primarily worn for locomotion. They exhibit different structures.

For example fungi, protists, animals, and plants, eukaryote, bacteria. There are different kinds of flagella that are primarily worn for locomotion. They exhibit different structures.

There are different kinds of flagella that are primarily worn for locomotion. They exhibit different structures.

flagellum

Difference between Cilia and Flagella

Both can be differentiated by their number, size, and function even though they have similar structures.

Cilia

cilia

  • Grouped into the category of protozoans, class Ciliata, in the Ciliated epithelium of the Metazoa and other classes.
  • It is usually present on the outer body surface such as larva of certain Mollusca, Annelida, and Nemertines, thus helping in locomotion.
  • It has similar structures and function as that of flagella, but cilium is shorter and movement is quite different.
  • They are present in large numbers.
  • It exhibits in radical motion.
  • Cilia often cover the entire cell.
  • They fuse into some protozoans to form cirri.

Flagella

  • Grouped into the category of protozoans, class flagellate, choanocyte cells of Metazoa and in other classes- in plants, in gamete cells, and in algae.
  • They are fairly long.
  • They are fewer in number.
  • It exhibits in coiled motion.
  • They are usually found at one end of the cell.
  • Flagella usually do not fuse.

Structure of Flagella

As mentioned earlier they are three types of flagella, those are Bacterial flagella, Eukaryotic flagella, and Archaeal flagella.

  1. Archaeal flagella are nonhomologous.
  2. Bacterial flagella are a coiled, thread-like structure, sharp bent, consisting of a rotary motor at its base and are composed of protein flagellin.  A shaft exists between a hook and a basal body passing through the protein rings in the cell membrane.
  3. Eukaryotic flagella are complicated cellular projections that pummel backward and forward and are found in protist cells, plants, and animals.

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