CELL CYCLE

Cell Cycle is the sequence of events in the life from the time a cell is produced unit it completes mitosis and produces new cells. The eukaryotic cell cycle consists of major phase i.e. Interphase and Mitotic phase (M phase) also called cell division.

Interphase

It is the period between cell divisions, during which the cell acquires nutrients from its environment, grows and replicates its chromosomes. The cell biologist divided Interphase into three sub phase i.e. G1, S and G2.

G1 phase (first gap in DNA Synthesis)

This is the phase in which most of the growth and metabolic activity occurs. The protein supply increase in the cell and number of many of its organelles like mitochondria, ribosome’s, Golgi bodies and carries out its specialized functions e.g. hormone synthesis and recreation. On later in G1phase, at a time called restriction point, the cell undergoes a kind of internal evaluation of its ability to complete the cell cycle and produce two viable daughter cells. If evaluation is positive the cell committed to DNA replication and cell division and if evaluation is negative the cells temporarily or permanently atop dividing are said to have entered a state of quiescence also called go phase.

For Example

Neurons oftenly undergo long periods of quiescence. Liver and kindly cells undergo the period of quiescence temporally and other cells such as epithelial, cells do not enter Go phase and continue throughout organism life.

S phase (DNA Synthesis Phase)

Chromosomes replication occurs in this phase. Each chromosomes is duplicated as a result each chromosome consists of two sister chomratids, which contains identical genes. During S phase, animal cells also duplicate their Centrioles.