Question

In S phase there is replication of DNA but not of the chromosomes then in Mitosis how the daughter cells and the parent cell have same no. of chromosomes??

Answer 1

Chromosomes and chromatids are different. Each chromosome has two chromatids (DNA+Histone protein=chromatid). Chromosome number remains same throughout mitosis but chromatid number changes. After DNA replicates in S phase there is twice the number of chromatids but same number of chromosomes ( as 2 chromatids are present in each chromosome) again in anaphase chromatids separate so chromatid no. is restored.