Final answer:
The structure with two barrel-shaped centrioles surrounded by pericentriolar material is known as the centrosome. This cell component is crucial for organizing microtubules and facilitating cell division processes like mitosis.
Step-by-step explanation:
The structure that contains two barrel-shaped centrioles surrounded by amorphous, electron-dense pericentriolar material is called a centrosome. The centrosome is an important part of the cell, serving as a microtubule-organizing center. It is found near the nucleus of animal cells and is crucial for various cellular processes, including cell division. Each centriole within the centrosome is a cylinder composed of nine triplets of microtubules, and these centrioles lie perpendicular to each other.
The centrosome functions as a major coordinating center for the cell's microtubules and plays a significant role in organizing them during cellular processes such as mitosis. It also plays a role in forming the mitotic spindle, which is essential for the separation of chromosomes during cell division. The centrioles within the centrosome are involved in this process by arranging the spindle fibers that pull the chromosomes apart.