🔍 1. What is the Cytoskeleton? (Cytoskeleton PDF)
The cytoskeleton is a complex, dynamic network of interlinking protein filaments present in the cytoplasm of all cells, including those of bacteria and archaea.[2] In eukaryotes, it extends from the cell nucleus to the cell membrane and is composed of similar proteins in the various organisms. It is composed of three main components: microfilaments, intermediate filaments, and microtubules, and these are all capable of rapid growth and/or disassembly depending on the cell's requirements.
🧫 2. Components of Cytoskeleton
Component Size Protein Function
Microtubules ~25 nm Tubulin Cell shape, chromosome movement, cilia & flagella
Microfilaments ~7 nm Actin Cell movement, muscle contraction, cytokinesis
Intermediate Filaments ~10 nm Keratin, vimentin, etc. Mechanical strength, cell stability
📘 Mnemonic to Remember
🧠 “MIC-MIC-IN”
MICrotubules – Largest
MICrofilaments – Smallest
INtermediate – In between
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🌀 3. Functions of Cytoskeleton
🧍 Maintains cell shape and structure
🚶♂️ Helps in intracellular transport of organelles
🧬 Chromosome movement during cell division
✂️ Cytokinesis (division of cytoplasm)
🧭 Guides vesicle movement and organelle positioning
🔍 4. Special Roles
Component Special Function
Microtubules Spindle fibers during mitosis
Microfilaments Amoeboid movement, cleavage furrow
Intermediate Filaments Nuclear lamina formation
🧪 NEET Focus Points
✅ Microtubules = tubulin + 25 nm
✅ Microfilaments = actin + 7 nm
✅ Intermediate filaments are not involved in motility
