Question at position 91 In eukaryotes the replication of chromosomal DNA occurs during:G2 phaseanaphaseG1 phaseprophaseS phase

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Question restatement: In eukaryotes, chromosomal DNA replication occurs during which phase?

Option 1: G2 phase. G2 is the second gap phase following DNA replication, primarily focused on preparing for mitosis and checking DNA integrity. Since replication has already occurred earlier, this option is incorrect for the replication timing.

Option 2: anaphase. Anaphase is a stage of mitosis where sister chromatids are separated and pulled toward opposite poles. It is a mitotic event, not a phase during which DNA replication happens, so this choice is incorrect.

Option 3: G1 phase. G1 is the first gap phase prior to DNA synthesis, during which cells grow and monitor conditions before replication. DNA replication has not yet started in G1, making this option inaccurate for the replication period.

Option 4: prophase. Prophase is the early stage of mitosis when chromosomes condense and the mitotic spindle forms. Since replication occurs before mitosis and prophase, this choice does not describe the replication timing.

Option 5: S phase. S phase, or synthesis phase, is the portion of the cell cycle when DNA replication takes place, duplicating the chromosomes so that sister chromatids are available for division. This is the correct description of the replication timing in eukaryotes.

Synthesis rationale: DNA replication must precede chromosome segregation; in eukaryotes, the replication origin firing and duplication occur specifically during S phase, followed by mitosis in later phases. The other phases listed are associated with growth before replication (G1), DNA duplication misalignment (G2 is post-replication), or mitosis (prophase and anaphase), so they do not describe the replication window.

Question at position 91 In eukaryotes the replication of chromosomal DNA occurs during:G2 phaseanaphaseG1 phaseprophaseS phase

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