Final answer:
The MTOC includes the centrosome and centrioles, which are essential for microtubule growth and organization, especially during cell division. While centrioles are typical in animal cells, plant cells have MTOCs similarly serving in mitosis without centrioles.
Step-by-step explanation:
The components that make up the microtubule-organizing center (MTOC) include the centrosome in animal cells, which contains a pair of centrioles. These centrioles are cylinders made up of nine triplets of microtubules arranged in a ring. The main function of the MTOC is to serve as an origin point for the growth of microtubules, which are crucial for cell shape, motility, and division.
Additionally, MTOCs are responsible for organizing the mitotic spindle during cell division. However, not all microtubules are organized by MTOCs. For example, plant cells typically lack centrioles but still possess MTOCs that function similarly to centrioles in animal cells during mitosis and meiosis.