Question

What happens if microtubules and microfilaments are absent in the cell?

Answer 1

In all cells of all domains of life I.e., archaea, bacteria, and eukaryotes, there is present a complex network of interlinking filaments and tubules that extend throughout the cytoplasm is called the cytoskeleton. There are three types of protein fibers in the cytoskeleton of eukaryotes; microfilaments, microtubules, and intermediate filaments.

Complete answer:
1. Microfilaments: They are the narrowest of all the three protein fibers in the cytoskeleton. They are made up of monomers of a protein called actin, combined to form a double helix structure. Microfilaments have a diameter of about 7nm. Because of actin monomers, microfilaments are also known as actin filaments. Actin filaments have polarity, due to structurally different ends.
Actin filaments perform several important roles in the cells. Actin serves as a track for the movement of a motor protein called myosin. Actin and myosin are abundant in muscle cells, where they form sarcomere, the unit of muscle contraction. Actin filaments help in the transport of cargoes, including vesicles and even organelles.
If actin filaments are absent in the cell, many cellular events requiring motion will halt. Muscles won’t contract. Transport of cargoes, cell motility, cell shape, and structure will be impaired.
2. Microtubules: They are the largest of the three types of cytoskeletal fibers. Microtubules have a diameter of 25nm. Monomers of microtubules are tubulin proteins that are arranged to form a hollow, straw-like tube. Each tubulin monomer consists of two subunits, alpha-tubulin, and beta-tubulin. Microtubules are dynamic structures, they grow and shrink by the addition or removal of tubulin proteins. Microtubules have directionality, meaning they have two different ends.
Microtubules play an important structural role in a cell. They help the cell to resist compression forces. In addition to structural support, microtubules perform specialized roles in a cell. For example, they provide tracks for motor proteins called kinesins and dyneins, which transport cargoes, and vesicles around the interior of the cell. During cell division, microtubules give rise to a structure called the spindle, which separates the chromosomes towards the opposite poles of the cell.
If microtubules are absent in a cell, cell shape will be deformed as it will lose resistance to compression forces. Transport of cargoes and vesicles will halt. Cell division won’t take place as a spindle won’t be formed.

Note:
Cytoskeleton supports the plasma membranes, provides the cell with its shape and mechanical resistance to deformation, aids in the correct positioning of organelles, provides tracks for the transport of vesicles, allows cells to move, and through association with extracellular connective tissue and other cells, it establishes the entire tissues.