consist of hollow tubes which provide support for the cell
The correct answer and explanation is:
Correct Answer: Microtubules
Microtubules are hollow tubes made of protein subunits called tubulin. They are an essential component of the cytoskeleton in eukaryotic cells and provide structural support. Microtubules are about 25 nanometers in diameter and can grow or shrink by adding or removing tubulin subunits, making them dynamic structures within the cell.
One of the key roles of microtubules is to maintain the shape of the cell. They form a rigid framework that resists compression, preventing the cell from collapsing or becoming deformed. Because of their tubular structure, they can bear tension and provide a track for intracellular transport. Motor proteins like kinesin and dynein “walk” along microtubules, carrying organelles, vesicles, and other cargo throughout the cytoplasm.
Microtubules also play an essential role in cell division. During mitosis and meiosis, they form the mitotic spindle, which helps separate chromosomes into daughter cells. The ability of microtubules to rapidly assemble and disassemble allows them to efficiently form the spindle and then break down after the division is complete.
In specialized cells, microtubules form structures like cilia and flagella. These are hair-like projections that extend from the cell surface and are responsible for movement. For example, the flagellum of a sperm cell helps it swim toward the egg, and cilia in the respiratory tract help move mucus and debris out of the lungs.
Overall, microtubules are essential for supporting the cell’s shape, enabling movement within the cell, and ensuring proper cell division. Their hollow tube-like design is perfectly suited for bearing loads and serving as highways for cellular components.