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:
- Microtubules are hollow tubular structures made of protein subunits.
- They provide structural support and play a key role in intracellular transport.
- 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.
- 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."
- 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.