Stages of mitosis
Technical Details of Mitosis
One can define mitosis in different ways and defining them biologically would be more essential to understand the process technically. In general, mitosis is a cell division process. However, technically, mitosis is more than that. Mitosis deals with specific details about chromosomes rather than just division of cell.
Mitosis – A Insight to the chromosome level partition
Mitosis can be defined as the process of dividing a cell into two identical halves with equal chromosomes in both the partitions. This means that chromosomes in one partition are an exact replica of the chromosomes in the next partition. This ensures that the cell is divided impartially. Nature has given us several wonderful mysteries to resolve. How this equal replica took place is one such mystery.
Arrangements and transformation inside a cell prior to partition
Scientists have analyzed that before partition the cell undergoes transformation. This transformation is nothing but to arrange the chromosomes in a certain order. Before even getting ordered, the chromosomes are replicated inside the single cell and then aligned with a determined format. Therefore, everything happens with a forestalled activity. This sort of replication, aligning and grouping is found to be happening in almost all eukaryotic cells.
Cell division in mitosis includes an INTERPHASE AND MITOSIS
The period between mitotic divisions - that is, G1, S and G2 - is known as interphase.
G1 phase. Prepares cell for division.
S phase. DNA synthesis and formation of 2 sister chromatids.
G2 phase. Assembly of cytoplasmic materials required for mitosis and cytokinesis.
M phase. The nuclear division (mitosis) followed by a cell division called cytokinesis.
Kinetochores and Chromosomes
Alignments and transformations inside the cell are initiated right when the chromosomes start their interaction with the microtubules. These are protein formations that form a spindle like structure. This spindle like structure in the conical form induces the chromosomes to replicate and arrange themselves as required for a division. The interaction between the chromosomes and these spindle shaped microtubules take place at only specific points and not elsewhere in the cell. These specific points in the cell are the kinetochores. Kinetochores location is no far from that of the chromosome. They are present right at the centromere of the chromosome.
While replicating the chromosome right inside the cell, the replica chromosome will also have kinetochores at its centromere. At this stage, the cell will have two chromosomes and two kinetochores. All this would come under mitosis stage and then the cytokinesis takes place where the cell splits into two with one chromosome and one kinetochores each. This would be the complete splitting of cell both internally and structure wise. Now internally the process leads to an avalanche effect and there would be so many replications leading to so many mitosis conditions in every cell.
Stages of Interphase
G1 phase: Synthesis of DNA. Cell increases in size. G in G1 is gap and the 1st is first gap phase.
S phase: DNA is made. S here means synthesis.
G2 phase: DNA has been made and is ready to the start prophase. cell makes proteins and continues to increase in size. G here means gap and the 2 means second. G2 phase is the 2nd gap phase.
The chromosomes condense.
Mitotic spindle and asters forms from centrosomes.
Microtubules lengthen, moving the centrosomes away from each other to opposite sides of the cell.
Nuclear membrane is no longer visible.
Polar fibres continues to expand to the centre of the cells from the poles.
Centromeres of sister chromatids line up at right angles of the equator of the spindles.
Centromeres start to move apart and the chromosomes move to the poles at each end of the cell.
The fibres become shorter as the chromosomes move to the poles.
The daughter chromosomes arrive at the spindle poles and begin to decondense into chromatin.
Microtubular networks of the mitotic spindle are redistributed into cytoskeletal components.
The process of cytokinesis is dividing the cytoplasm into 2 daughter cells by pinching of the cell. This actually starts in late anaphase and continues through telophase.
Stages of Mitosis
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