CELL DIVISION PROCESS
Reproduction is one of the most important things that a cell has to undergo for most of its lifespan. It is a complex process that is undertaken in multiple steps, one at a time. There is a sequence attached to these steps which are carried out in a manner such that all information (DNA and genetic) along with the molecules are divided in the appropriate manner. End result is two similar daughter cells with the same characteristic features. In the initial stage, the cell prepares itself for the division process. All elements that need to be distributed are separated in pairs.
Once this is done, the actual cell division process starts. There are a total of 4 phases, which may be summarized as under. Each phase has its own significance and hence should complete in the desired way else, problems may occur.
1) Prophase: In this phase, discrete chromosomes are formed with chromatic condensing. Two poles are formed at the opposite ends known as “spindles” and the nuclear envelope breaks down. The chromosomes align themselves in a straight line at the center and these spindle fibers get attached to them. The place of attachment is known as centromere and the chromosome is known to have two strands known as chromatids.
2) Metaphase: The chromosomes get attracted to the metaphase plate due to which, they shift from their original random position to a straight line. The spindles get stronger and then attach more firmly to the centromere. An interesting fact to note here is that the chromosomes align perpendicular to the poles so that the force of pull is the maximum when the chromatids separate from the chromosome pairs.
3) Anaphase: This is the phase where the actual physical work can be seen. Due to the pull from the poles, disintegration occurs and the chromatids start to move towards the opposite poles. The segregated chromatids are then considered as full chromosomes with each pole getting a total of 23 pairs. Along with this movement, the spindles start to become shorter (they are always attached to the centromere and move with the element). Once they have reached their respective poles, the cell prepares itself for the last phase of mitosis.
4) Telophase: The last phase of the cell division process, the fully paired chromosomes are now at their respective poles and the formation of a nucleus along with the cytoplasm starts. The nucleus starts to form around the chromosomes (they are a part of the nucleus) and the cytoplasm everywhere else. Formation of nucleus is supplemented by the small fragments of nuclear envelope that gets distributed. Cytokinesis ensures that other organelles required in the cells are produced. The cell membrane starts to divide and by the end of it, we have two distinct daughter cells.
After a period of time, the daughters undergo the same process again and again hence generating more and more similar cells – an important process in genetics research too. If we compare this process amongst the different animals, the similarities are strikingly similar which further allow for better studies.