Will this be 2n and not just 2?
Q. S-phase: During this phase, replication of DNA takes place. Each chromosome contains two sister chromatids, that are attached to a common centromere. At this stage the cell is 4n (4 copies of each DNA molecule, 2 in each homologous chromosome).

Dear student.

We know that chromosomes are the condensed form of DNA in a cell. During S phase of the cell cycle, the replication of the DNA takes place and each DNA strand produces its new copy, so the content of the DNA becomes double. But as the newly synthesised DNA does not get separated from the parent DNA in the S phase, so chromosome number remains same i.e (2N). When cell enters the mitosis, the newly synthesised DNA separates from the parent DNA and get condensed to form separate chromosome. Now the cell becomes temporarily 4N i.e chromosome number doubles. The nucleus divides first and each nucleus receives one set of chromosomes (2N). After complete cell division, the two cells are formed with same number of chromosomes i.e 2N


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