THE SHORT AND ONLY LIFE OF A CELL

Interphase:
It is the phase of the cell cycle in which the cell spends the majority of its time and performs the majority of its purposes(obtaining nutrients, growing, and conducting other "normal" cell functions) including preparation for cell division.

Interphase generally lasts at least 12 to 24 hours in mammalian tissue.

STAGES OF INTERPHASE:

There are three stages of interphase, with each phase ending when a cellular checkpoint checks the accuracy of the stage's completion before proceeding to the next. The stages of interphase are:

• G1:GAP 1:

During this stage new organelles are being synthesized, so the cell requires both structural proteins and enzymes, resulting in a great amount of protein synthesis and a high rate of metabolism in the cell.

CHECKPOINT:
The G1/S transition is a major checkpoint in the regulation of the cell cycle. Depending on levels of nutrients, energy and external factors, cells must decide to enter the cell cycle or move into a non-dividing state known as G0 phase.

• G0:GAP ZERO:

A cell may pause in the G1 phase before entering the S phase and enter a state of dormancy called the G0 phase.

• S Phase: 

To produce two similar daughter cells, the complete DNA instructions in the cell must be duplicated. DNA replication occurs during this S (synthesis) phase.

• G2: GAP 2: 

It is a period of rapid cell growth and protein synthesis during which the cell readies itself for mitosis. Curiously, G2 phase is not a necessary part of the cell cycle, as some cell types (particularly young Xenopus embryos and some cancers) proceed directly from DNA replication to mitosis.