Biology · Cell Cycle and Cell Division · NEET
S phase comes after G1. The order is G1 first, then S. In G1 the cell grows but does not copy its DNA. Only in S phase does DNA replication happen. So the cell must finish G1 before it enters S. Never write S before G1.
G2 (Gap 2) is the preparation stage before division. The cell can only prepare to divide after its DNA has been copied, and DNA copying happens in S phase. So S must come first, then G2. In G2 the cell makes proteins needed for mitosis. Order: S → G2 → M.
For counting the sequence, we start with G1. A new cell that has just formed from division enters G1, then goes G1 → S → G2 → M. Because it is a cycle, M is followed again by G1 of the next cell, but the standard NEET answer for the sequence starts at G1: G1 → S → G2 → M.
Interphase = G1 + S + G2. These three are the non-dividing growth and preparation phases. M phase (mitosis) is separate and is the actual division. So interphase is the first three of the four, and it takes more than 95% of the total cycle time.
G2 is part of interphase, not M phase. Interphase has three sub-phases: G1, S and G2. The cell is still preparing during G2. Only when G2 ends does the M phase (division) begin. A common trap is to think G2 is the start of mitosis.
The correct sequence of phases of cell cycle is:
Following are the stages of cell division: A. Gap 2 phase B. Cytokinesis C. Synthesis phase D. Karyokinesis E. Gap 1 phase. Choose the correct sequence of stages.
The correct sequence of adult cell cycle phases is ________.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
G1 → S → G2 → M. G1, S and G2 form interphase; M phase is the actual division. This is the single most asked point in NEET from this chapter.
G1 = Gap 1 (growth, no DNA copy). S = Synthesis (DNA is copied). G2 = Gap 2 (prep and protein-making before division). M = Mitosis (nuclear then cytoplasm division).
In a 24-hour human cell cycle, interphase (G1 + S + G2) takes about 23 hours (over 95%) and M phase takes less than an hour. Most of the time the cell is in interphase, not dividing.
DNA is copied only in the S (Synthesis) phase. DNA content doubles from 2C to 4C, but the chromosome number stays the same (each chromosome now has two sister chromatids).
Yes. After M phase the new cell enters G1 again, so the cycle repeats. Some cells instead exit into G0 (quiescent stage) and stop dividing until needed.
