Rucete ✏ Campbell Biology In a Nutshell
Unit 2 THE CELL — Concept 6.6 The Cytoskeleton Is a Network of Fibers that Organizes Structures and Activities in the Cell
The cytoskeleton is a dynamic network of fibers extending throughout the cytoplasm, providing structural support, organization, and facilitating various cellular activities.
1. Components of the Cytoskeleton
- Microtubules: Hollow rods made of tubulin proteins.
- Structure: About 25 nm wide; grow/shrink by adding/removing tubulin dimers.
- Function: Maintain cell shape, aid intracellular transport, form the mitotic spindle.
- Microfilaments (Actin Filaments): Thin rods made of actin proteins.
- Structure: About 7 nm wide; form twisted double chains.
- Function: Maintain shape, enable movement (e.g., pseudopodia), drive muscle contraction.
- Intermediate Filaments: Fibrous proteins coiled into cables.
- Structure: 8–12 nm wide; made of proteins like keratins.
- Function: Provide strength, anchor organelles, reinforce cell shape.
2. Functions of the Cytoskeleton
- Structural Support: Maintains cell shape and prevents collapse.
- Intracellular Transport: Acts as tracks for moving vesicles/organelles via motor proteins.
- Cell Motility: Enables movement using structures like cilia, flagella, or lamellipodia.
- Cell Division: Forms the mitotic spindle (microtubules); actin assists in cytokinesis.
3. Dynamic Nature
The cytoskeleton is highly dynamic, constantly rebuilding and adjusting to help the cell move, divide, and respond to changes.
In a Nutshell
- The cytoskeleton is a complex network of fibers that provides structural support and organizes cellular components.
- It includes microtubules, microfilaments, and intermediate filaments, each with unique roles.
- It supports movement, division, transport, and structural integrity within cells.
- Its dynamic nature enables the cell to adapt to internal and external changes.