Question

Microtubules are constituent of
A. Cilia, flagella, and peroxisomes
B. Spindle fibres, centrioles, and cilia
C. Centrioles, spindle fibres, and chromatin
D. Centrosome, nucleosome, and centrioles

Answer 1

Hint: The microtubules are present in all eukaryotic cells' cytoplasmic matrix. They are composed of flagella, cilia, centrioles, basal and mitotic bodies.

Complete Answer:
- Microtubules are tubulin polymers, part of cytoskeleton, which provide structure and shape to eukaryotic cells. Microtubules can grow up to 50 micrometers and are incredibly dynamic. The microtubule's exterior diameter is 23 to 27 nm while the internal diameter ranges from 11 to 15 nm.
- They are produced by the polymerization into protofilaments of a dimer of two globular proteins named beta and alpha tubulin, that can then form a hollow tube lateral to form the microtubule. The most popular type of a microtubule is composed of 13 tubular protofilaments.
- In many cellular processes, microtubules are very essential. They preserve the cell structure and shape the cytoskeleton with microfilaments and intermediate filaments. In the internal structure the flagella and cilia are also located. They provide intracellular transport platforms and participate in a range of processes in cellular systems, including passage of secretory vesicles, organelles and macromolecular assemblies intracellular.
- They are also required in cell division and form the key components of mitotic spindles used to differentiate eukaryotic chromosomes. The centrosome located in the middle of several animal cells or basal bodies found in cilia and flagella or the pole bodies found in most of these fungi are nucleated and arranged by Microtubule Organizing Cents (MTOCs).

Thus, the correct answer is option B. i.e., Spindle fibres, centrioles, and cilia.

Note: Spindle fibres make up the protein matrix that promotes mitosis and meiosis. Two cylindrical forms in a cell organelle or centrosome are centrioles. Fine hair-like membranous outgrowths are cilia and flagella.