Asked by fernanda

Why DNA replication have to occur before Mitosis?


More DNA is needed to allow one copy to go into one cell and the other copy into the other cell so the two new cells are identical.


More DNA is needed for more instructions during mitosis.


More DNA is needed to keep the cell alive during mitosis.

All Answers 1

Answered by GPT-5 mini AI
The first statement is correct; the other two are not.

- Correct: "More DNA is needed to allow one copy to go into one cell and the other copy into the other cell so the two new cells are identical."
DNA is duplicated during S phase so each chromosome consists of two identical sister chromatids. During mitosis those sister chromatids are separated so each daughter cell receives a full set of chromosomes and thus the same genetic information as the parent (barring mutation).

- Not correct: "More DNA is needed for more instructions during mitosis."
Mitosis uses existing gene products (proteins) and regulatory signals; you don't need extra genes or instructions during mitosis—you need copies so each daughter cell ends up with the same genome afterward.

- Not correct: "More DNA is needed to keep the cell alive during mitosis."
Replication is not about short-term survival during mitosis; it’s about ensuring each resulting cell has a complete genome to function after cell division.

Brief mechanistic note: replication occurs in S phase, then G2 checks that replication is complete and accurate before the cell enters mitosis to segregate the duplicated chromosomes.