Figure 13.

The spindle cycle in budding yeast. In the center of the figure, drawings represent the structure of budding yeast cells as they traverse the cell cycle. Around the edges are models made from tomographic reconstructions of the MT component of yeast spindles at each stage of mitosis. (a) There is only one centrosome but MTs grow from it into the cell’s nucleus; (b) The centrosome is duplicated and more shorter MTs project into the nucleus; (c) There are now two functional centrosomes, sitting side by side, each projecting MTs into the nucleus. At this stage, the spindle is in the process of attaching sister kinetochores to sister spindle poles; (d) A bi-polar spindle has formed; (e) The cell is advanced in anaphase B and the sister chromosomes are well separated; (f) A long, slender spindle runs from pole to pole (green and magenta MTs), and the chromosomes are drawn tightly around each pole. This spindle severs as the cell divides at cytokinesis, and the cell returns to state A. Redrawn from [43] by Eileen O’Toole. This image is displayed under the terms of a Creative Commons License (Attribution-Noncommercial-Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/.