Question

Which of the following forms the cytoskeleton of a cell?
A) Microtubules
B) Microfilaments
C) Lysosomes
D) Both A and B

Answer 1

Hint: Cytoskeleton is a complex network of interlinking protein filaments which is present in the cytoplasm of the cell of mammals including bacteria and archaea. Cytoskeleton of a cell extends from the nucleus of the cell to the cell membrane of the cell and composed of various proteins.

Complete answer:
Cytoskeleton of a cell extends from the nucleus of the cell to the cell membrane of the cell and is composed of various proteins.The cytoskeleton of the cell is composed of three components.
Components of cytoskeleton:
>Microfilaments
>Intermediate filaments
>Microtubules
a) Microfilaments : Microfilaments are also called as the actin filaments.They are mostly composed of pectin protein.The molecule of a microfilament is the two strands of actin wound in a spiral.Microfilaments are the thinnest filaments in the cytoskeleton.Microfilaments help in cytokinesis (division of a cell into two daughter cells) and in cell motility.
b) Intermediate filaments :Intermediate filaments are called intermediate because their size lies between the size of microfilaments and the microtubules.These filaments are made up of many kinds of proteins like keratin, vimentin, desmin and lamin.All intermediate filaments are found in the cytoplasm of the cell except for the lamins.Lamin are present inside the nucleus of the cell and support the nucleus.
 The intermediate filaments maintain the cell shape, bear tension and provide structural support to the cell.
Microtubules : Microtubules are the largest cytoskeleton’s fibres.These are the hollow tubes that are made up of alpha and beta tubulin.Microtubules form the structure like flagella which help in the movement of the cell. They are also found in the cilia which increases the surface area of the cell.Most of the microtubules come from the cell organelle called a centrosome which is a microtubule organizing center (MTOC).Microtubules are important in forming the spindle apparatus, in transporting molecules within the cell and in formation of cell wall in plants.
Therefore, it has been clear from the above discussion that both microtubules and microfilaments form the cytoskeleton of a cell.

Hence, option D is the correct answer.

Note:The main function of the cytoskeleton of a cell is to give cell shape. The cytoskeleton organizes the cell and keeps the cell’s organelles in place. Cytoskeleton of a cell also helps in the movement or organelles and other substances throughout the cell.