The document discusses centrioles and basal bodies. It states that centrioles are cylindrical structures found in the cytoplasm of eukaryotic cells that help form the mitotic spindle during cell division. When located beneath the cell membrane, centrioles are called basal bodies and anchor flagella or cilia. The document describes the structure of centrioles and basal bodies including their nine microtubule triplets arranged in a pinwheel shape and other components like linkers and rootlets. Their functions include organizing microtubules and forming cilia, flagella, and the mitotic spindle to help in cell division.