Function of a microtubule is/are:
**Core Concept**
Microtubules are dynamic, hollow, tubular structures composed of tubulin proteins. They are a key component of the cytoskeleton, providing structural support, shape, and mechanical stability to cells.
**Why the Correct Answer is Right**
Microtubules play a crucial role in various cellular processes, including:
* Maintaining cell shape and division, through their dynamic assembly and disassembly.
* Regulating organelle movement, such as vesicle transport and axonal transport along microtubule tracks.
* Interacting with motor proteins, such as kinesin and dynein, to facilitate movement and transport.
* Participating in cell signaling, through the regulation of protein-protein interactions and the organization of signaling complexes.
**Why Each Wrong Option is Incorrect**
**Option A:** Microtubules are not primarily involved in the regulation of cellular metabolism.
**Option B:** While microtubules do interact with the cell membrane, they are not directly responsible for maintaining cell-cell adhesion.
**Option C:** Microtubules are not the primary component of the nuclear envelope; this function is attributed to the nuclear lamina.
**Clinical Pearl / High-Yield Fact**
Microtubules are targeted by several antineoplastic agents, including taxanes (e.g., paclitaxel) and vinca alkaloids (e.g., vincristine), which disrupt microtubule dynamics and inhibit cell division.
**Correct Answer: C. Maintaining cell shape and division, through their dynamic assembly and disassembly.**