Cytoskeleton

An internal scaffold of protein fibers running through the cytoplasm — it gives the cell shape, support, and the ability to move.

Components

• Microfilaments — the thinnest fibers (made of actin); drive cell movement and shape changes.
• Intermediate filaments — rope-like fibers that bear mechanical stress.
• Microtubules — the thickest; act as tracks for internal transport and pull chromosomes apart during cell division.

What it does

• Structure — maintains and changes cell shape.
• Movement — powers crawling, contraction, and the beating of cilia and flagella.
• Internal transport — serves as the railway along which organelles and vesicles are hauled.

Key idea

Far from being a fixed frame, the cytoskeleton is constantly built up and torn down, letting the cell move, divide, and reshape itself.