In what part of the cell cycle does chromosomal duplication occur?

• A. S phase of interphase
• B. M phase (mitosis)
• C. G2 phase of interphase
• D. G1 phase of interphase

Answer: (A)

Verified step by step guidance

1. Understand the cell cycle: The cell cycle is divided into interphase and the M phase (mitosis). Interphase consists of three subphases: G1, S, and G2. Each phase has specific functions related to cell growth and division.
2. Focus on chromosomal duplication: Chromosomal duplication refers to the replication of DNA, which is essential for ensuring that each daughter cell receives a complete set of genetic material during cell division.
3. Identify the phase responsible for DNA replication: DNA replication occurs during the S phase (synthesis phase) of interphase. This is when the cell synthesizes a complete copy of its DNA in preparation for division.
4. Clarify the roles of other phases: G1 phase is primarily for cell growth and preparation for DNA synthesis, G2 phase involves preparation for mitosis, and the M phase is where mitosis and cytokinesis occur, dividing the cell into two daughter cells.
5. Conclude that chromosomal duplication specifically occurs during the S phase of interphase, as this is the phase dedicated to DNA replication.