why the creation of only DNA copy is not sufficient for cell division?
Answers
Explanation:
Replicating DNA is fragile, and can break during the duplication process. In fact, broken chromosomes are often the source of DNA rearrangements and can change the genetic program of a cell. These changes can trigger a growth advantage in a single cell in your body, and when that cell continues to divide, tumors arise. Fortunately, our cells have defense mechanisms to shield us from these damaging events.
In the eukaryotic cell cycle, chromosome duplication occurs during "S phase" (the phase of DNA synthesis) and chromosome segregation occurs during "M phase" (the mitosis phase). During S phase, any problems with DNA replication trigger a ‘'checkpoint" — a cascade of signaling events that puts the phase on hold until the problem is resolved. The S phase checkpoint operates like a surveillance camera; we will explore how this camera works on the molecular level. The last 60 years of research in bacterial species (specifically, Escherichia coli) and fungal species (specifically, Saccharomyces cerevisiae), have continually demonstrated that several major processes during DNA replication are evolutionarily conserved from bacteria to higher eukaryotes.