Biology · Cell: The Unit of Life · NEET
The cytoskeleton has three types of fibres: microtubules, microfilaments and intermediate filaments. NCERT states it is 'an elaborate network of filamentous proteinaceous structures consisting of microtubules, microfilaments and intermediate filaments.' If a NEET question lists only two of these and asks you to complete the set, the missing one is usually intermediate filaments - students often forget it.
Microtubules are made of a protein called tubulin and are hollow tubes; they are the thickest of the three. Microfilaments are made of a protein called actin and are the thinnest, solid fibres. Simple way to remember: microTUBules = TUBulin (both have TUB), microFilaments = actin (thin, like a fine hair).
No. The cytoskeleton is NOT bound by any membrane. It is made only of protein fibres floating in the cytoplasm. This is why it is grouped with other non-membrane-bound structures like ribosomes and centrioles. NEET sometimes tests this by asking which structures lack a membrane.
NCERT gives three functions: (1) mechanical support, (2) motility (movement), and (3) maintenance of the shape of the cell. In NEET 2023 the answer to 'which function is carried out by cytoskeleton' was Motility. So if you see options like nuclear division, protein synthesis, transportation and motility - the cytoskeletal function among them is motility.
Microtubules are the building units of spindle fibres, centrioles and cilia (and flagella). NEET 2016 asked exactly this and the answer was 'Spindle fibres, centrioles and cilia.' Peroxisomes, chromatin and nucleosomes are NOT made of microtubules, so watch out for those distractors.
Microfilaments (made of actin) help in amoeboid movement, like in Amoeba and in our own macrophages and white blood cells. They cause the streaming of cytoplasm that forms pseudopodia (false feet). So actin filaments are directly linked to crawling-type cell movement.
Which of the following functions is carried out by cytoskeleton in a cell?
Microtubules are the constituents of:
Choose the correct statements regarding cell organelles and their inclusions. A. The endomembrane system includes Golgi complex, endoplasmic reticulum and mitochondria. B. Rough endoplasmic reticulum bears ribosomes on its surface. C. Both mitochondria and plastids have circular DNA. D. A network of microtubules, microfilaments and intermediate filaments present in the cytoplasm is called cytoskeleton. E. Mitochondrion is a single membrane-bound structure.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Microtubules are made of the protein tubulin, and microfilaments are made of the protein actin. Intermediate filaments are made of various fibrous proteins.
Yes, the cytoskeleton is present in all eukaryotic cells, both plant and animal cells. It is a normal part of the cytoplasm.
It is a small but frequently asked NCERT topic. Direct one-liner questions on its three components and three functions have appeared in NEET 2016, 2023 and 2026, so it is high-yield for the marks-per-effort it gives.
No. The cytoskeleton has no DNA and no membrane. It is purely a network of protein fibres in the cytoplasm.
Cytoskeleton is the internal fibre network of the whole cell. Cilia and flagella are hair-like outgrowths of the cell membrane that use microtubules (in a 9+2 axoneme) for movement. Microtubules are shared, but the structures are different.
