EK Biology 1001 confusion (#184 on page 33, passage 209)

[littlejuan]

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[sleepy425]

A culture containing one thousand cells is expected to display what percentage of labile interphase cells?

A. 5% of cells will be in interphase
B. 847 cells will be in interphase
C. Between 93 and 97 percent will be in interphase.
D. Almost every cell will be in interphase.


They say the answer is C, and cite the paragraph: "Prior to mitosis, a cell will spend 95% of its time in a resting interval between division."

BUT, the passage also states, "Labile cells are constantly in the mitotic cycle undergoing division"

If they are constantly in mitotic division, wouldn't a small percentage be in the interphase stage?

Just because the cells are constantly dividing doesn't mean that they don't have to replicate their DNA and go through the other steps of the cell cycle. Labile cells just don't get stuck in the G0 (the non-dividing state). Since G1, S, and G2 are much longer than M phase, most cells will be in interphase. The mitotic cycle is not M phase, it's the entire replicating cell cycle that includes M phase. G0 is basically a non-mitotic branch off of the mitotic cycle.

 

[littlejuan]

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