Answer on Biochemistry Question for floyd roque
In general, most cells require much more time to grow and double their mass of proteins and organelles than they require to duplicate their chromosomes and divide. Partly to allow more time for growth, most cell cycles have exrra gap phases - a G1 phase between M phase and S phase and a G2 phase between S phase and mitosis.
Thus, the eucaryotic cell cycle is usually divided into four sequential phases : G1, S, G2, and M. G1, S, and G2 together are called interphase. In a typical human cell proliferating in culture, interphase might occupy 23 hours of a 24-hour cycle, with I hour for M phase. Cell growth occurs throughout the cell cycle, except during mitosis.
The two gap phases aren’t a simple time delays for cell growth. They also provide time for the cell to monitor the internal and external environment to ensure that conditions are suitable and preparations are complete before the cell commits itself to the major upheavals of S phase and mitosis. The G1 phase is especially important in this respect. Its length can vary greatly depending on external conditions and extracellular signals from other cells. If extracellular conditions are unfavorable, for example, cells delay progress through G1 and may even enter a specialized resting state known as G0 (G zero), in which they can remain for days, weeks, or even years before resuming proliferation. Indeed, many cells remain permanently in G0 until they or the organism dies (Alberts et al., 2008).
Right answer: this phase is called “G1 period”.
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