Can there be mitosis without DNA replication in ‘S’ phase?

No, mitosis cannot occur without DNA replication during the S phase.

Importance of DNA Replication in Mitosis

• Chromosome Duplication: During the S phase of interphase, DNA replication ensures that each chromosome is duplicated, resulting in two sister chromatids per chromosome. This duplication is essential for maintaining the chromosome number in daughter cells.

• Equational Division: Mitosis is an equational division, meaning it produces two daughter cells with the same chromosome number as the parent cell. Without DNA replication, the daughter cells would receive incomplete or incorrect sets of chromosomes, leading to genetic abnormalities.

Consequences of Absent DNA Replication

• Incomplete Chromosome Sets: If DNA replication does not occur, the cell would attempt to divide without having the necessary genetic material, resulting in daughter cells with incomplete or incorrect chromosome numbers.

• Cell Cycle Arrest or Cell Death: Cells have checkpoints that monitor DNA replication. If replication is incomplete or absent, these checkpoints can halt the cell cycle, preventing mitosis from proceeding. If the checkpoint mechanisms fail, it can lead to cell death.

Conclusion

DNA replication during the S phase is a critical prerequisite for mitosis. Without it, the cell cannot accurately divide its genetic material, leading to potential cell cycle arrest, genetic abnormalities, or cell death.