Is interphase really a "resting phase"? What exactly happens in G1, S and G2?
Aarav Kulkarni11th Sample
13 Oct 2026 · 1 min read
I made a checklist for Cell Cycle and Cell Division (obviously) and the very first item is already confusing me.
My old school notes call interphase the "resting phase", but NCERT says it's the time when the cell is preparing for division by undergoing both cell growth and DNA replication in an orderly manner. So it's not resting at all? Then why is it called that in so many places?
NCERT also says that a human cell divides roughly every 24 hours, with the M phase lasting only about an hour, while yeast can complete a cycle in about 90 minutes. If the M phase is that short, then interphase is most of the cycle. Is that the main reason people say "resting"?
My specific questions:
- What are the main events of G1, S and G2? I want a clean list.
- In which phase does the centriole duplicate in animal cells? I have it written as G2 in one place and S in another.
- What is G0? Is a G0 cell dead?
- Does DNA content change at G2 compared with S?
I'll turn the answers into a checklist, I promise 🙂
8 answers & replies
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[+][–]Meera Patel11thSample· 6d ago
"Resting" is a misleading name. Under the microscope, a cell in interphase doesn't look like it is dividing because the chromosomes are not condensed, but it is metabolically very active. NCERT's wording is better: interphase is the phase between two successive M phases, and it is where the cell grows and the DNA replicates.
Events:
- G1: cell grows, metabolically active, but DNA is not replicated
- S: DNA replicates; the DNA content goes from 2C to 4C but the chromosome number stays the same
- G2: proteins are synthesised in preparation for mitosis while growth continues
[+][–]Diya Menon11thSample· 6d ago
Centriole: S phase! NCERT says in animal cells, during S phase, DNA replication begins in the nucleus and the centriole duplicates in the cytoplasm. I used to think G2 too because the centrosome gets used right after that, ahh. Anyway so S phase does both jobs 😄
[+][–]Yash Tiwari11thSample· 6d ago
bhai G0 matlab cell dead hota hai na? Like the cell exits the cycle and mar jata hai?
[+][–]Nisha Verma12thSample· 6d ago
Yash, no. G0 is called the quiescent stage. Cells that are not going to divide further, or not dividing for the time being, exit G1 and enter G0, and they remain metabolically active. They just don't proliferate unless called to. Many cells in the adult animal body, like heart cells, are in this stage. Dead cells are not "in G0", they're dead.
[+][–]Aarav Kulkarni11thSample· 6d agoAuthor
This clears G0 completely. Adding to the checklist: "G0 = quiescent, NOT dead".
[+][–]Yash Tiwari11thSample· 6d ago
oh ok bhai thanks 😅 my bad
[+][–]Kavya NaikDropperSample· 6d ago
On the DNA content question: after S phase, the DNA amount is doubled (4C) and stays 4C through G2 and until anaphase/telophase splitting. G2 doesn't add more DNA. In G2 the cell checks the replicated DNA, makes proteins needed for division, and keeps growing. That's why people say G2 is the preparation for M phase.
[+][–]Ishita GoyalDropperSample· 6d ago
Your 24-hour thing matters for exam sums too. A quick rule: M phase ≈ 1 hour in a 24-hour cycle, so interphase is the rest (~95% of the cycle). Don't memorise a minute count for G1, S, G2 though, NCERT doesn't need it.
