Cell Cycle Definition: For the purpose of dividing eukaryote, the cells have to pass through a series of stages, which collectively known as the cell cycle. The cell cycle consists of Interphase: G1 (Gap 1), S (for synthesis), G2 (Gap 2), in these phases genetic material replicates; and an M phase; in this phased process of mitosis occurs to partitioning the genetic material and divides the cells.
Interphase is the longest stage of the eukaryote cell cycle. During this phase, a cell spends most of its life. For cell reproduction, the cell has to perform some activities for preparation. This phase used to divide the cell by replicate the DNA. During passing through interphase, the cell gain nutrients create and uses of proteins, and some other molecules. Then it starts the process of cell division by reproducing, or making exact another copy of DNA.
Gap 1 or G1 is the first stage or sub-phase of interphase. In Gap 1, the chromosomes in the nucleus have not replicated or reproduce, and the cell grows up. The cell becomes increases in size because it has to divide. If the cell not grows increase, after division its size ultimately becomes too small. After the division, again and again, it became smaller and smaller until there was nothing will left. Gap 1 can be different in the time to perform its function because it depends on the type of cell. Different cells take a different length of time to grow up and for replicated. Healthy cells which have the ability to perform their work properly stay in this stage for weeks or years. If they stay in this sub-phase for a long period of time, they enter in ‘Gap 0 or G 0’ phase, which is suspended the animation. Some special internal and external signals needed to get out from G 0. There is a transition sub-phase between G1 and S, known as restriction point. Synthesis:
Synthesis or, S stage is the second stage of interphase. The cells enter this sub-phase when the genetic material of cells is duplicated. Each chromosome replicated, and a pair of sister chromosomes produce. A chromosome is a strand of DNA covered around protein. Chromosome divides when DNA strand unwrap and separated from each other. Now, these strands serve as templates new strand of DNA that is formed. In the nucleus, free-floating nucleotides attach themselves with nitrogen bases of the template strand. Newborn chromosome becomes half of the new strand and half of the original parent strand. If the cell is a somatic cell, it enters in mitosis after interphase, and sister chromatids will be separated and create two similar copies of the genome. It will entre in meiosis if cell rose the gamete. In meiosis, chromosomes separately divide, and sister chromatid creates a cell with half of the full genome. After synthesis, the cell must prepare for cell division.
When DNA replicated during synthetic sub-phase, the cell enters into Gap2 or G2 sub-phase. In Gap2, cell given rise to the cytoplasm, and ready to replicate many important organs. In plants, both chloroplasts and mitochondria must be replicated or have the same copies to provide the ability to produce energy to the daughter cells. In animals, the mitochondria are replicated to provide the ability to produce enough energy to daughter cells. Gap2 perform function until cell enters into cell division stage ‘M’. In mitosis, the cell divides and the phase starts again. And if the cell divides in the meiosis, before entering into interphase and repeat the phase, gamete fertilizes with DNA.