Spindle Fibres

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What are Spindle Fibres?


A network of filament that forms mitotic and meiotic spindle during cell division is termed as spindle fibre. Movement of chromosomes during mitosis and meiosis cell division is due to spindle fibres.

Spindle fibres constitute mitotic and meiotic spindle during cell division. They are formed by microtubules and play an important role during nuclear division. They are responsible for the segregation of sister chromatids and movement of chromosomes during mitotic and meiotic division.

Structure, Formation and Location

  • Spindle fibres are made up of tubulin proteins and RNA. It is composed of microtubules, which is a polymer of 𝜶 and 𝞫-tubulin dimer
  • They are formed from the centrosome, they are formed at the opposite poles during cell division and attach to chromosomes at the equatorial plate
  • Centrosomes always have assembled microtubules. Spindle fibres start increasing in length on getting signal for cell division
  • During metaphase, they radiate from centrioles and get attached to arms or kinetochore of chromosomes
  • At anaphase stage of cell division, spindle fibres pull sister chromatids towards opposite poles
  • Spindle fibres, along with associated proteins, condensed chromosomes and centrosomes or asters form the spindle apparatus

Spindle Fibers Function

  • Spindle fibres help in the division of genetic component of the cell during division
  • Spindle fibres are formed during both mitosis and meiosis cell division
  • Spindle fibres get attached to kinetochores and arms of chromosomes and help in segregation and movement of chromatids
  • During metaphase, chromosomes get aligned in the middle with the help of spindle and then move to the opposite poles during anaphase stage

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Frequently Asked Questions

What is a spindle fiber?

Spindle fiber is a network of filaments that are formed during the cell division process. They help in the movement of chromosomes during both mitosis and meiosis.

What are spindle fibers made of?

Spindle fiber is most abundantly composed of the microtubule, which is a polymer of 𝜶 and 𝞫-tubulin dimer. Also, the spindle fiber is made up of several hundreds of associated proteins.

What are the two types of spindle fibers?

The two types of spindle fibers are the kinetochore and interpolar fibers. The interpolar stretches continuously from one spindle to another. The kinetochore fiber stretches from the pole to the kinetochore.

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