Question

Microtubules are constituents of:
A. Centrosome, nucleosome and Centrioles
B. Cilia, flagella and peroxisome
C. Spindle fibers, Centrioles and cilia
D. Centrioles, spindle fiber and chromatin

Answer 1

Hint: Microtubules are nucleated and arranged by microtubule organizing centers, like the Centrosome found within the center of the many animal cells or the basal bodies found in cilia and flagella, or the spindle pole bodies found in fungi.

Complete answer: Microtubules are polymers of tubulin that form a part of the cytoskeleton and supply structure and shape to eukaryotic cells. An elaborate network of filamentous proteinaceous structure present in the cytoplasm is collectively referred to as the cytoskeleton. Microtubules can grow as long as micrometers and are highly dynamic. Microtubules are vital during a number of cellular processes. The minus end of the microtubule is present at the microtubule organizing center and the microtubule grows from it so the plus end is away from the origin. Microtubules are hollow cylinders made up of repeating protein structures, specially dimers of alpha and beta tubulin. Dimers are complexes of two proteins alpha tubulin and beta tubulin bind to each other and form a dimer and then multiple units of these dimers bind together, always alternating alpha and beta to form a chain called a protofilament.
So, the correct answer is “Option C”.

Note:
The microtubules are found in the cytoplasmic matrix of all eukaryotic cells. They also occur in cilia, flagella, Centrioles, basal bodies and mitotic apparatus. Spindle fibers from the protein structure, which helps in mitotic and meiosis. Centrioles are the two cylindrical structures of a cell organelle called Centrosome. Cilia and flagella are fine hairlike outgrowths of the membrane. While peroxisomes are the microbodies.