The part of the cell made up of microtubules and involved in organizing cell division, cilia, and flagella is the centrosome.

Here's a breakdown:

* Microtubules: These are hollow tubes made of the protein tubulin. They provide structural support, act as tracks for intracellular transport, and play a crucial role in cell division and movement.

* Centrosome: This is a small, dense region in the cytoplasm of animal cells. It contains two centrioles, which are cylindrical structures composed of microtubules arranged in a specific pattern.

* Cell Division: During cell division, the centrosome duplicates and the two centrosomes move to opposite poles of the cell. Microtubules from each centrosome then attach to chromosomes, pulling them apart and ensuring that each daughter cell receives a complete set of chromosomes.

* Cilia and Flagella: These hair-like structures, responsible for movement, are also composed of microtubules arranged in a specific pattern called the "9+2" structure. The centrosome plays a role in the assembly and anchoring of these structures.

So, in summary, the centrosome is the key organizer, composed of microtubules, that directs cell division, cilia, and flagella formation.