Part A Which of the following statements best describes microtubules? Microtubules are made up of subunits of tubulin, and are structures along which substances are transported in the cell. Microtubules are permanent cellular structures that help the cell to move from place to place. Microtubules are made up of subunits of actin, and function in muscle contraction and changes in cell shape. Microtubules are fibrous proteins coiled into cables that maintain cell shape and anchor the nucleus.
