The phenomenon of the cell cycle is considered a series of events that occur when a cell is growing and dividing during its lifespan to produce two new daughter cells. The cell cycle is majorly divided into two distinct stages – the Interphase stage and the stage of mitosis. It is said that a cell spends most of its lifespan in the cell cycle interphase stage, after which it progresses to the mitotic division stage. During the cell cycle interphase stage, the cell undergoes growth, and the DNA of the cells are replicated. And in the mitotic division phase, the copied DNA and the cytoplasm of the cells separate equally into two daughter cells.
Interphase cell cycle explanation
During the cell cycle interphase stage, the cell undergoes the normal procedures while preparing for the cell to divide and undergo mitotic division. The cell has to meet various internal and external prerequisite conditions to make a smooth transition from the cell cycle interphase to the mitotic cell division. The interphase stage is characteristically divided into three sub-phases – G1, S and G2.
G1 Phase
The cell cycle interphase stage contains the first stage, the G1 stage. It is also called the First Gap Phase because very small changes are visible in the cells in the first gap phase. But the G1 phase shows a higher activity level in the biochemical level.
The main work or role of the cells in this sub-phase is to accumulate the building blocks of genetic material, that is, the chromosomes and DNA and their associative proteins, and also to accumulate and store enough energy content or energy reserves so that it enables them to complete the process of replication of each chromosome in the nucleus of the cells.
S Phase
During the cell cycle interphase stage, the DNA material of the nucleus is contained in a semi-condensed form of chromatin fibres or configuration. In the S or Synthesis phase, there is the occurrence of the replication of DNA, which results in the creation of two identical daughter cells or daughter nuclei, which contain identical copies of the chromosomes, often called sister chromatids.
These sister chromatids are attached to the centromere. At this stage of development, the chromosome contains two sister chromatids and is considered duplicated or a copy. The S Phase also witnesses the replication of the centrosome. The centrosomes are the origin points of the mitotic spindles during the division, which is the medium through which the chromosomes move towards the opposite extreme sides during the mitotic division.
The centrosome that is duplicated in the cell cycle interphase stage usually consists of centrioles that are rod-like structures and are positioned at right angles to each other. The main role of the centrioles is to organise and aid the cell division. These rod-like structures are not found present in many eukaryotic origin species, including fungi and plants.
G2 Phase
The G2 phase is also called the Second Gap phase of the Cell Cycle Interphase. This is the phase where the cell utilises the resting period and stores as well as replenishes the energy content. In this phase, the cell also synthesises the essential proteins for the duplication and manipulation of the genetic material or the DNA.
The cytoskeleton of the cells in this phase is degraded and dismantled to create new sources and pathways for the spindle fibres to generate and connect to opposite sides. It is possible to notice an increase or additional growth of cells in this stage. This phase is when the cell has to complete all prerequisite conditions to smoothly transition to the mitotic stage of division.
Key Terms
- Interphase – the cell cycle interphase is the stage of the cell cycle where the cell grows and develops so that it can duplicate the DNA or the genetic material.
- Sister Chromatids – the sister chromatids are the two identical strands or fibres of a single chromosome or the DNA or the genetic material that has to separate during mitotic division to form identical two separate nuclei.
- Mitotic Spindle – the mitotic spindle arises from the centrosomes in many cells. These are the medium through which the sister chromatids of the chromosomes have to move to the opposite extreme ends for mitotic division.
Conclusion
This article explained the cell cycle interphase and its various stages and key aspects. The cell cycle plays a major role in the division of cells and also in informing new cells. The cell cycle interphase is the longest period in the cell cycle of many organisms and is divided into three sub-phases – the First Gap, or G1 Phase, the Synthesis of DNA Phase of the S phase, and the last are the Second Gap or the G2 Phase. Each sub-phase has a distinct role in the cell cycle and the preparation of the prerequisites of the mitotic cell division.