Cytoskeleton | Description, Structure, & its Function

Cytoskeleton | Description, Structure, & its Function

It is made up of extremely minute, fibers, filamentous, & tubular proteinaceous structures which form the structural framework inside the cell. The cytoskeleton occurs only in eukaryotic cells & is involved in many functions such as mechanical support, motility, maintenance, of the shape of the cell.

Structure of Cytoskeleton

Cytoskeleton | Description, Structure, & its Function
Cytoskeleton | Description, Structure, & its Function

(A) Microtubules

The microtubules are found in the cytoplasmic matrix of all eukaryotic cells. They also occur in cilia, flagella, centrioles & basal bodies, mitosis apparatus etc. Prokaryotic cells lack microtubules.

The microtubules are hollow, unbranched cylinders, generally about 25 nm in diameter with a hollow core of about 15 nm. The boundary of a microtubules is composed of 13 parallel protofilaments. Each protofilament is made up of α & β subunits of tubulin protein (non contractile protein). The assembly & disassembly of microtubules require GTP & Ca2+.

Function :

  1. These help in the spindles & astral rays formation during cell division.
  2. These form the cytoskeleton of cilia & flagella.
  3. These help in generating the shape, rigidity & form of the cell & cell motility.
  4. Microtubules help in the anaphasic movement of chromosomes.
  5. Microtubules help in the intracellular transport of nutrients & inorganic ions.
  6. Position of future cell plate is determined by microtubules.

(B) Microfilaments

The microfilaments are found in eukaryotic cells. The microfilaments are Solid, unbranched, rod – like fibrils of indefinite length. They are mainly composed of a globular protein actin, but have filamentous protein myosin also. They form an extensive network in the cytoplasm of cells & may be associated with plasma membrane.

Function : 

  1. The microfilaments provide support to plasma membrane.
  2. These represent the contractile system of the cell & are involved in cytoplasmic steaming & amoeboid movements.
  3. Help in pseudopodia formation.
  4. These help in the formation of cleavage furrow during cell division.

(C) Intermediate Filaments

Non – contractile hollow filaments of acidic proteins. They are involved in formation of scaffolds for chromatin & in forming a basket around nucleus.

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