Mitosis

The Mitosis is one of two types of cell division in eukaryotes. It is used to reproduce body cells, whereby two new cells with an identical set of DNA are created from an old cell.

What is Mitosis?

In mitosis, cell division occurs with the aim of reproducing two new, young cells with an identical set of DNA from an aging cell. Mitosis happens in four phases, in which the DNA first splits in the middle. The missing piece is reproduced, there are two exactly identical strands of DNA in the cell nucleus.

After that, the cell splits itself into two new cells. The cell organelles are newly produced thanks to the DNA and there are two identical cells. Mitosis is the core part of the reproduction of body matter.

Depending on the cell type, human cells have a lifespan of hours to days or weeks, after which they are old and have to be replaced by new ones. Mitosis also occurs during wound healing, whereby new body substance must also be built up to replace the injured substance.

Mitosis must be distinguished from meiosis, in which reproductive cells are produced. With the exception of egg and sperm cells, cell division is always mitotic in nature and produces the original cell in duplicate to replace aging body substance.

Function & task

Mitosis enables the reproduction of cells whose DNA set corresponds exactly to the cells in the body that are already present. As a result, all types of body substance can be renewed and the cell type from which mitosis originates is renewed identically.

There are only a few exceptions to cells that do not arise through classic mitosis, in which an identical new cell is created from an old cell. Red blood cells, for example, die after their average lifespan and are reproduced (mitotically) by the bone marrow.

However, stem cells are present in the bone marrow. These are able to reproduce any cell type through mitosis, even if it does not perform exactly the same function as itself, i.e. also red blood cells. Muscle and nerve cells are formed in a similar way. All of these cell types do not have their own nucleus, which is, however, a prerequisite for mitosis, since the DNA is in the nucleus.

Mitotic division processes are particularly important in children who are growing. In this case, mitosis not only has to replace aging cells, but also build up more body mass over the years. That is why a healthy diet is very important, especially for children, as they have a higher need due to their growth with faster cell division than adults.

Illnesses & ailments

Mitosis is a complex process that is also dangerous due to the splitting and reproduction of DNA. As vital as mitosis is, it is also the point where cancer originates.

Due to radiation, chemical substances or other environmental influences that are capable of epigenetically influencing or altering the DNA or interrupting its process of division, errors in the DNA cleavage during mitosis can occur.

A faulty set of DNA is created in one or two cells, these degenerate cells continue to divide and can develop further at a very rapid pace. Benign or malignant tumors develop, which either emit toxins themselves or exert pressure on vital organs, which can be fatal.

This serious type of error in mitosis can be compared to errors in meiosis, which lead to defective reproductive cells and thus to congenital hereditary diseases.

Due to shifts in the DNA that are not harmful and occur naturally (e.g. crossing-over), mutations can occur. These are "experiments" of nature, whereby, for example, different coat colors in the same animal species have developed in the animal world.

The white variant of the hare, the mountain hare, for example, tended to survive in cold regions of the world, while the brown hare has better chances of survival in more southern latitudes - but without mutations, the different coat colors would not have developed. Mutations occur all the time, but this only becomes noticeable in the next generation.

Mutations in mitosis result in various diseases or differences, but these do not always have to be a disease. As the DNA changes, the cell also produces other proteins. These proteins are in turn incorporated into the construction of new body substances and substances as usual, but the usual product that the cell is actually responsible for manufacturing is not created.

An example is sickle cell anemia, in which the red blood cells take on a sickle-like shape. In malaria areas this is an advantage, because sickle cell anemia is associated with resistance to malaria. For northern Europeans, on the other hand, this mutation would be a disadvantage, as the sickle shape of the red blood cells means that as much oxygen can no longer be transported as in the normal form.

This example shows in humans how experimental mutations can be in mitosis and that they are proof of the existence of evolution - because what would be regarded as a disease in this country is a protection against a disease prevailing in other parts of the world.