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 replicates in the S phase of the cell cycle and initiates at specific regions in the DNA sequence known as DNA replication ‘origins’. A number of proteins participate in DNA replication and the process is subject to scrutiny by cell surveillance mechanisms called cell cycle checkpoints.

Detailed explanation-4: -During S phase, genomic DNA is replicated and packaged into chromatin. The identical copies of each chromosome are known as sister chromatids, and they are tightly associated together through G2 phase and early mitosis.