DNA replication occurs before mitosis and cell division to ensure that each daughter cell receives a complete and identical copy of the genome. This replication takes place during the S phase of the cell cycle, producing sister chromatids for each chromosome so that during mitosis, when the cell divides, each daughter cell inherits one full set of chromosomes. Without DNA replication before mitosis, daughter cells would end up with incomplete or missing genetic information, unable to function properly and maintain genetic continuity. Thus, DNA replication is a crucial step for successful cell division and the preservation of genetic information across cell generations.
Importance of DNA Replication Before Mitosis
- DNA replication ensures that there are two identical copies of each chromosome (sister chromatids) attached at the centromere.
- During mitosis, these chromatids are separated, so each daughter cell receives a full chromosome set.
- This maintains the chromosome number constant and preserves the genetic information for cell function and survival.
Timing and Regulation
- DNA replication happens in the S phase before mitosis (the M phase).
- It is tightly controlled by cell cycle checkpoints to ensure replication occurs only once per cycle.
- Proper replication and segregation prevent mutations and genetic abnormalities that could lead to diseases like cancer.
In summary, DNA replication before mitosis is essential to duplicate the genome, allowing equal and accurate distribution of genetic material during cell division, ensuring that daughter cells function independently with the full genetic blueprint.
