Figure 13-34. Stages at which checkpoint controls can arrest passage through the cell cycle.

Figure 13-34Stages at which checkpoint controls can arrest passage through the cell cycle

DNA damage due to irradiation or chemical modification prevents G1 cells from entering the S phase and G2 cells from entering mitosis. Unreplicated DNA prevents entry into mitosis. Defects in assembly of the mitotic spindle or the attachment of kinetochores to spindle microtubules prevent activation of the APC polyubiquitination system that leads to degradation of the anaphase inhibitor. Consequently, cells do not enter anaphase until all kinetochores are bound to spindle microtubules. [Adapted from A. Murray and T. Hunt, 1993, The Cell Cycle: An Introduction,W. H. Freeman and Company.]

From: Section 13.7, Checkpoints in Cell-Cycle Regulation

Cover of Molecular Cell Biology
Molecular Cell Biology. 4th edition.
Lodish H, Berk A, Zipursky SL, et al.
New York: W. H. Freeman; 2000.
Copyright © 2000, W. H. Freeman and Company.

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