BIOL 341 Chapter Notes - Chapter 18: G2 Phase, Mitogen, Dna Replication
Document Summary
Why cell division: reproduction, development and growth, cell replacement. Interphase: g1-- interval ( gap ) before dna replication --some non-dividing cells remain in this phase forever ( g0 , determines if the environment is favorable to enter the s phase, s -- dna replication (synthesis) --chromosomes duplicated. Synthesize dna: g2 -- interval after dna replication note: these gaps are important for growth, preparation, makes sure there is no dna damage, m phase. Cdk concentrations are fixed" (constant) but cyclin concentration go up and down. Cyclin mrna is at a constant level in cells. Distinct cyclins associate with specific cdks and control different aspects of the cell cycle. Cyclin levels rapidly decreased by ubiquitylation and proteolysis. What happens if cells don"t pass the g1 checkpoint: the cell will die. Dna damage will halt movement to the s phase: p21 inhibits g1 cdk, p27 binds to m cdk and inactivates.
