Cytoskeleton,Motility and Shape


The cytoskeleton is an intricate network of filamentous protein structures found in the cytoplasm of eukaryotic cells. It plays a crucial role in various cellular functions. 


The cytoskeleton consists of three primary components:

1. Microtubules:

- Microtubules are hollow tubular structures made of protein subunits.

- They provide structural support and play a key role in intracellular transport. 

2. Microfilaments:

- Microfilaments are thin, solid protein filaments involved in various cellular processes, including cell motility and maintaining cell shape. 

3. Intermediate Filaments:

- Intermediate filaments are thicker and more stable protein filaments.

- They contribute to the mechanical strength of the cell.


- The cytoskeleton is involved in numerous functions within the cell, including: 

1. Mechanical Support:

- It provides structural support to the cell, helping it maintain its shape and integrity. 

2. Motility:

- The cytoskeleton is essential for various forms of cell movement, such as cell division, cilia and flagella movement, and intracellular transport. 

3. Shape Maintenance:

- It helps maintain the shape of the cell and is crucial for specialized cell functions. 

Cilia and Flagella

  • Cilia (singular: cilium) and flagella (singular: flagellum) are slender, hair-like projections that extend from the cell membrane.  
  • They play crucial roles in cellular movement and are found in both eukaryotic and prokaryotic cells.


- Cilia are relatively short structures that function like oars, producing coordinated movements.

- They can either move the cell itself or create fluid movement in the surrounding environment. 


- Flagella are longer than cilia and are primarily responsible for cell movement. They provide propulsion to the cell.

- It's important to note that the structure of prokaryotic bacterial flagella differs from eukaryotic flagella.





- Cilia and flagella consist of a central core called the axoneme, which contains a set of microtubules aligned parallel to the structure's long axis.

- The axoneme typically comprises nine doublets of peripheral microtubules arranged radially, with a pair of centrally located microtubules. This arrangement is known as the "9+2 array." 

Additional Components:

- The central microtubules are connected by bridges and surrounded by a central sheath.

- Radial spokes link the central sheath to one tubule of each peripheral doublet.

- Nine radial spokes provide stability to the structure. The peripheral doublets are interconnected by linkers. 


- Both cilia and flagella emerge from basal bodies, which are centriole-like structures located at the base of these hair-like projections.