Answer: Option A
:
A
Eukaryotic cells (particularly) animal and lower plant cells) have the ability to adopt averiety of shapes and carry out directed movements because they have a network of proteinfibres that support the shape of the cell and anchor organelles to fixed location. This network is called cytoskeleton. Later is made up ofactin filaments, which are made of two strands of the fibrous protein twisted together and usually occur in bundles.
(i)Actin Filaments are ubiquitous, and are concentrated below the plasma membrane in bundles known
as stressfibres, which may have a contractile function.
(ii)Microtubules, which are composed of 13 stacks of tubulin protein subunits arranged side by side to
form a tube. Microtubules are comparatively stiff cytoskeletal elements that serve to organize
metabolism and intracellular transport in the non-dividing cell.
(iii)Intermediate filaments,which are composed of overlapping staggered tetramers of protein. This
molecular arrangement allows for a rope-like structure that imparts tremendous mechanical
strength to the cell.