Question
During which phase (s0 of the cell cycle, the amount of DNA in a cell remains at the 4C level if the initial amount is denoted as 2C?
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Go and G1
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G1 and S
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Only G2
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G2 and M
Solution
D.
G2 and M
During the S or synthetic phase, the DNA content double, i,e, from 2C to 4C for all diploid cells. The G2 phase follows the S-phase and is called second growth phase or pre-mitotic gap phase. In G2 phase the synthesis of DNA stops, therefore, the DNA level remains 4C if initial was 2C
However, the formation of RNA and protein continues as they are required for the multiplication of cell organelles, spindle formation and cell growth. This amount becomes, half (i.e,) 2C only during anaphase (in mitosis) when chromosomes separate.
