Final answer:
Microtubules contribute to various cellular functions, including intracellular transport formation of the mitotic spindle during cell division and the structure of filopodial extensions, as well as making up cilia and flagella. They do not contribute to the human RBC disk-like shape or orientation of plant cellulose microfibrils.
Step-by-step explanation:
Microtubules Contribution to Cellular Functions: Microtubules are integral components of the cytoskeleton in eukaryotic cells, contributing to various cellular functions. One of the key roles of microtubules is to assist in intracellular transport, where they serve as tracks for motor proteins to move vesicles and organelles. Additionally, microtubules are essential during cell division, forming the mitotic spindles which help in the separation of chromosomes. They also support the structure of filopodial extensions and are the main components of cilia and flagella, providing motility to cells.However, when examining the contributions of microtubules, it is important to identify which of the listed cell structures or processes they do not influence.
Microtubules contribute to each of the following except the human red blood cell (RBC) disk-like shape. This is because mature human RBCs lack a nucleus and the majority of the cytoskeletal components, including microtubules. Instead, the biconcave disk shape of RBCs is primarily maintained by the organization of the cytoskeletal proteins spectrin and actin beneath the plasma membrane. Furthermore, microtubules do not contribute to the orientation of plant cellulose microfibrils; this process involves other complexes including the cellulose synthase complex.