Cell cycle and apoptosis · USMLE Step 1

Which phase of the cell cycle is characterized by DNA synthesis (duplication of the genome)?

  1. G1 phase
  2. S phase
  3. G2 phase
  4. M phase
Show answer and explanation

Correct answer: S phase

The S phase is when DNA replication occurs, producing sister chromatids for each chromosome. This ensures that each daughter cell will receive a full complement of genetic material.

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