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 composed of tubulin proteins.
Structure: Each microtubule is about 25 nm in diameter and can grow or shrink by adding or removing tubulin dimers.
Function: They maintain cell shape, facilitate intracellular transport, and are involved in cell division by forming the mitotic spindle.
Microfilaments (Actin Filaments): Thin, solid rods made of actin proteins.
Structure: Approximately 7 nm in diameter, these filaments form twisted double chains.
Function: They support the cell's shape, enable cell movement through pseudopodia, and are essential in muscle contraction.
Intermediate Filaments: Fibrous proteins coiled into cables.
Structure: With a diameter of about 8–12 nm, they are composed of various proteins like keratins.
Function: They provide mechanical strength, anchor organelles, and maintain cell integrity.
2. Functions of the Cytoskeleton
Structural Support: Maintains cell shape and prevents deformation.
Intracellular Transport: Acts as tracks for the movement of organelles and vesicles, especially via motor proteins like kinesin and dynein along microtubules.
Cell Motility: Facilitates movement through structures like cilia, flagella, and lamellipodia.
Cell Division: Microtubules form the mitotic spindle, while actin filaments assist in cytokinesis.
3. Dynamic Nature
The cytoskeleton is not a static structure; it continuously remodels itself, allowing the cell to adapt to changing conditions, move, and divide.
In a Nutshell
The cytoskeleton is a complex network of fibers that provides structural support and organizes cellular components.
It comprises microtubules, microfilaments, and intermediate filaments, each with distinct structures and functions.
Beyond maintaining shape, it plays crucial roles in intracellular transport, cell movement, and division.
Its dynamic nature enables cells to respond and adapt to their environment effectively.