Twenty-Three Hours of Work, One Hour of Drama

You'll learnhow a cell's time splits across G1, S, G2, and M, and when the chromosome count changes.

A cell spends the overwhelming majority of its life in interphase — growing, duplicating organelles, and copying every base of its genome in S phase. Mitosis, the part every textbook draws, is the short bit at the end, and 46 chromosomes go into S and 46 come out. Ten short steps; press Next for each one.

AP BIOLOGY · 10 STEPS · 6 QUICK CHECKS · INTERPHASE ≈ 23 OF 24 HOURS · DNA COPIED IN S, NOT M · v6

G₁ → S → G₂ → M · 24 h model cell

Before you start

What you're looking at

The cell cycle drawn as a ring, to scale for a 24-hour model cell, filling through interphase toward one short hour of mitosis.

The question

Where in the cycle is the DNA copied, and when does the chromosome count actually change?

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