The cytoskeleton is a dynamic, internal framework of protein filaments that gives a cell its shape, organizes its contents, and enables movement—both within the cell and of the cell itself. It’s essentially the cell’s structural support system, much like a skeleton in the body.
🔑 Definition:
The cytoskeleton is a network of protein fibers found throughout the cytoplasm of eukaryotic cells. It provides structural support, enables intracellular transport, and helps cells divide, move, and change shape.
🧬 Main Components of the Cytoskeleton:
| Component | Protein Type | Function |
|---|---|---|
| Microfilaments | Actin | Cell shape, muscle contraction, cell movement, and cytokinesis |
| Intermediate filaments | Various (e.g., keratin, vimentin) | Provide mechanical strength and resist stress |
| Microtubules | Tubulin | Transport of organelles/vesicles, mitosis (spindle formation), cilia/flagella movement |
⚙️ Functions of the Cytoskeleton:
| Function | Description |
|---|---|
| Structural support | Maintains cell shape and integrity |
| Cell division | Forms the mitotic spindle that separates chromosomes |
| Intracellular transport | Acts like “highways” for motor proteins (e.g., kinesin, dynein) to carry organelles or vesicles |
| Cell motility | Enables movement through structures like lamellipodia, filopodia, and flagella |
| Anchoring organelles | Keeps organelles in proper positions |
| Signal transmission | Helps cells respond to environmental cues |
📦 Microfilaments (Actin Filaments):
- ~7 nm thick
- Involved in:
- Muscle contraction
- Cell movement (e.g., crawling)
- Formation of cleavage furrow in cell division
📦 Intermediate Filaments:
- ~10 nm thick
- Tissue-specific (e.g., keratin in skin, neurofilaments in neurons)
- Provide tensile strength, especially in mechanically stressed tissues
📦 Microtubules:
- ~25 nm thick (largest)
- Hollow tubes made of α- and β-tubulin
- Important in:
- Mitosis (spindle fibers)
- Cilia and flagella for movement
- Axonal transport in neurons
🧪 Why the Cytoskeleton Is Important:
| Biological Role | Significance |
|---|---|
| Development | Guides cell shape and tissue structure |
| Immunity | Helps immune cells move and engulf pathogens |
| Neural function | Microtubules enable axon growth and transport of neurotransmitters |
| Cancer | Abnormal cytoskeletal function affects cell division and migration |
🧠 In Summary:
The cytoskeleton is the cell’s internal support system, enabling everything from shape maintenance to intracellular trafficking and movement. It plays vital roles in both the everyday functioning and adaptability of cells.