Is all DNA replicated? Figure 17-14 Checkpoints in the Are all chromosom Is environment favorable? attached to the spi cell-cycle control system Information about the completion of cell-cycle events. G2 CHECKPOINT METAPHASE CHECKPOINT as well as signals from the environment, ENTER M EXIT N can cause the control system to arrest the cycle at specific checkpoints. The most prominent checkpoints occur at locations marked with yellow boxes CONTROLLER ENTER S G1 CHECKPOINT Is environment favorable?
M G Restriction point Growth factors
Fignre 14.7 Cell cycle of fission yeast (A) Fission the cell cycle, even in the absence of further growth factor stimulation.On yeasts grow by elongating at both ends
(A) Daughter cell Mother cell START Mating factors Cell size Figure 14.5 f the cell cycle of budding yeast (A) The cell cycle of Saccharomyces cerevisiae is regulated primarily at a point in late G,called CTA DT
Temperature-sensitive cdc28 mutant Permissive Daughter cell Nonpermissive Mother cell START ART Figure 14.12 Properties of S cerevisiae cdc28 mutants The temperature-sensitive cdc28 mutant replicates normally at the permissive temperature. At the nonpermiss temperature, however, progression through the cell cycle is blocked at START