47. A friend of yours measured the quantity of DNA in grasshopper cells growing in the
cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of
DNA/cell. What would be the amount of DNA/cell in grasshopper cells seen in the
anaphase of mitosis?
A. 50 units
B. 100 units
C. 400 units
D. 200 units
Grasshopper cells in G2 phase contain 200 units of DNA per cell after S phase replication doubles the G1 amount (100 units) to 4C DNA content. During anaphase of mitosis, sister chromatids separate and move to opposite poles, but the whole cell retains this full 200 units until cytokinesis divides it into two daughter cells each with 100 units. The correct answer is D. 200 units.
Cell Cycle DNA Content Overview
G1 phase holds unreplicated 2C DNA (100 units here). S phase synthesizes exact copies, yielding G2’s 4C (200 units) with chromosomes as joined sister chromatids. Mitosis (prophase to telophase) maintains 4C total until physical cell split.
Option Analysis
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A. 50 units: Wrong; implies quarter content, matching neither mitosis (halves post-cytokinesis) nor meiosis II end products.
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B. 100 units: Incorrect; equals one daughter cell or G1 amount, but question asks whole cell in anaphase before division.
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C. 400 units: Impossible; no extra replication occurs, as G2 already maxes post-S phase.
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D. 200 units: Correct; anaphase distributes replicated DNA (still 4C total) without reducing per-cell quantity pre-cytokinesis.
Exam Relevance for CSIR NET
Such questions test interphase-mitosis transitions and C-value constancy. Sketch timelines: G1 (2C) → S → G2/M (4C) → daughters (2C). Grasshopper examples highlight conserved eukaryotic patterns.
