AP BIOLOGY

Detailed explanation-1: -In the eukaryotic cell cycle, chromosome duplication occurs during “S phase” (the phase of DNA synthesis) and chromosome segregation occurs during “M phase” (the mitosis phase).

Detailed explanation-2: -S phase is the period during which DNA replication occurs.

Detailed explanation-3: -DNA Synthesis During S phase, an enzyme called helicase unwinds the DNA strand, in the same way that you would unzip a zipper. The two single DNA strands can then be used as templates to form two identical double DNA strands.

Detailed explanation-4: -During the S phase of the cell cycle, the entire genome is replicated. There is a high level of orderliness to this process through the temporally and topologically coordinated activation of many replication origins situated along chromosomes.