Figure 17-24. The DNA replication checkpoint.

Figure 17-24The DNA replication checkpoint

In the experiments diagrammed here, mammalian cells in culture were treated with caffeine and hydroxyurea, either alone or in combination. Hydroxyurea blocks DNA synthesis. This block activates a checkpoint mechanism that arrests the cells in S phase, delaying mitosis. But if caffeine is added as well as hydroxyurea, the checkpoint mechanism fails, and the cells proceed into mitosis according to their normal schedule, with incompletely replicated DNA. As a result, the cells die.

From: Intracellular Control of Cell-Cycle Events

Cover of Molecular Biology of the Cell
Molecular Biology of the Cell. 4th edition.
Alberts B, Johnson A, Lewis J, et al.
New York: Garland Science; 2002.
Copyright © 2002, Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter; Copyright © 1983, 1989, 1994, Bruce Alberts, Dennis Bray, Julian Lewis, Martin Raff, Keith Roberts, and James D. Watson .

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