In eukaryotic cells, which phases together constitute the full cell cycle framework within which DNA replication occurs?

Introduction / Context:
DNA replication is restricted to a defined window of the eukaryotic cell cycle, but understanding that window requires viewing the entire cycle framework that orchestrates growth, synthesis, checkpoint control, and division.

Given Data / Assumptions:

• Interphase consists of G1, S, and G2.
• M phase encompasses mitosis and cytokinesis.
• DNA replication itself occurs during S phase.

Concept / Approach:
The complete canonical eukaryotic cell cycle is G1 (growth), S (DNA synthesis), G2 (preparation/checking), and M (mitosis). Many exam items ask for the set of phases constituting the cycle, not only the single phase where replication happens.

Step-by-Step Solution:

Verification / Alternative check:
Cell-cycle markers (cyclins/CDKs) and DNA content analysis (flow cytometry) define these stages, with 1C → 2C DNA increase in S phase.

Why Other Options Are Wrong:

• G1, G2 and M: omits S phase.
• S, G2 and M: omits G1.
• G2 and M: incomplete.
• S only: names the synthesis phase, not the whole cycle.

Common Pitfalls:
Answering “S phase” when the question asks for the cell-cycle composition rather than the replication window.

Final Answer:
G1, S, G2 and M