What is mitosis?
Mitosis is a process of cell division used by eukaryotes. During this process a parent cell is split into two identical daughter cells with matching chromosomes. Mitosis is a part of the cell cycle in the mitotic phase where division occurs and is estimated to make up approximately 10% of the total cell cycle.
Process of mitosis
How does mitosis work? Mitosis is a process of cell division which occurs exclusively in eukaryotic organisms. Mitosis does not occur uniformly among living organisms and can vary between domains and even species, it occurs relatively quickly however is still a highly complex process. The process is divided into eight stages which occur in quick succession to each other.
Stages of Mitosis and phases of cell cycle
The interphase is the stage in which a cell prepares its self for division. This is not technically part of mitosis but makes up for the 90% of the cell cycle. During this stage the nucleus begins to produce proteins and cytoplasmic organelles. The interphase is further divided into three sub phases called first gap, synthesis and second gap. During the synthesis phase is where chromosomes are duplicated for the division. During the interphase most of the organelles and components are replicated to make the process of mitosis quick and efficient.
Proprophase occurs exclusively in plants because to the unique structure of vacuolated plant cells. The nucleus must first move to the center of the cell for plants before the actual prophase can begin. A phragmosome, or cytoplasmic sheet, forms which begins to map out the areas to be divided after fixing the nucleus in the center of the cell.
Chromatins are a loosely bundled coil of genetic material which have already been replicated in the synthesis phase of the interphase. During the prophase these chromatins tighten their coils with the aid of proteins to form chromosomes.
Centrosomes are organelles near the nucleus which coordinate with microtubules to determine the center of the cell. Centrosomes are pushed to opposing sides of the cell by molecular motor proteins along a path of microtubules to begin the separation process.
The prometaphase begins after the centrosomes have reached their desired destinations. During this phase the nuclear membrane begins to deteriorate where microtubules begin drifting into the nucleus. Chromosomes form into kinetochores which act as a hook for the microtubules to attach themselves to the centromere.
After the attachment process in prometaphase the centrosomes begin shifting and aligning themselves on opposing ends of the cell membrane creating the spindle equator between them. An even alignment is attained by the centrosome poles pulling away from each other while acting as the center of the cell.
In anaphase the chromosomes split from each other when the proteins separate in the chromatids. These chromtids then become daughter chromosomes and microtubules begin shrinking thus pulling the chromosomes closer to the centrosome. Polar microtubules begin to elongate which start pulling the centrosomes away from each other causing the cell to expand.
During the telophase the nuclear membrane begins reforming over the chromosomes. Cytokinesis begins and with the cleavage furrow from where the cell membrane begins collapsing on its self. The cleavage furrow forms from the forces caused by the polar microtubules elongating away from each other. This stages marks the completion of the mitosis cycle when the chromosomes settle around a new nuclei and expand back into chromatins.
Although cytokinesis begins at the same time as telophase it is a separate phase and continues longer than the mitosis cycle. This is the separation process from which the daughter cells are split off from the parent cell. The cleavage furrow pinches in on its self and vesicles from the golgi apparatus follow microtubules towards the center of the cell where they begin developing the separating cell wall. After the process of cytokinesis is finalized the identical daughter cells contain the same genome as the parent cell they duplicated from.