Gene expression

The Gene expression describes the expression and development of a genetically predisposed characteristic of a living being. On the other hand, there is genetic information that is not expressed and that can only be detected using a DNA analysis.

What is gene expression?

Every living being has a multitude of genes, but not all of the characteristics contained in DNA are ever developed, that is, expressed. Some genes remain inactive, but are present and can still be inherited. Depending on the genotype of the sexual partner, a non-expressed gene can appear in the generation of the offspring, i.e. it can be expressed.

When it comes to gene expression, two identical genes come into question, each of which comes from the mother and the father and, to a certain extent, competes with one another. There is a dominant and a recessive gene. In humans, one dominant gene usually "wins" over a recessive or two recessive genes are expressed equally and result in a visible characteristic that lies between that of mother and father.

In some plants, for example, the colors red and white are both recessive and when mixed, pink flowers are created in the offspring generation, as gene expression of both genes takes place.

Function & task

Humans have a large number of genes on their 47 pairs of chromosomes. Like every living being, he has half from his mother and the other half from his father. From an evolutionary point of view, it is now a matter of expressing those genes that are most helpful for the survival of the new person.

In the course of evolution, for example, it turned out that gene expression of the genes for dark skin in warm, sunny regions of the world is an advantage for humans, while gene expression of the genes for light skin was better in less sunny parts of the world. In the case of two recessive genes, in particular, it means that one of the two or a mixed form can be expressed through the gene expression, which means that the species is able to continuously improve and become more viable.

Therefore, even genetically identical, identical twins with two recessive genes show slightly different characteristics, for example the smallest differences in hair or eye color.

So-called mutations of individual genes, i.e. spontaneous changes due to the constant formation of new body cells, have always occurred in almost every multicellular living being. In this way, for example, mountain hares or polar bears came into being: gene mutation developed the gene expression of white hair, the mutated animals proved to be more viable than their brown conspecifics in polar regions and prevailed in these parts of the world. Such processes, which are based on mutation-induced alternating gene expression, take millennia and sometimes millions of years before they become widespread.

It is not only the gene expression of his own body that proves useful for humans, but also that of bacteria. With the help of various antibiotics it is possible, among other things, to inhibit the bacterium in its gene expression and thus to cause vital functions to fail. The bacterium dies and humans can recover from a bacterial infection.

Furthermore, research is currently being carried out into whether genes that cause cancer can be inhibited in their gene expression so that people genetically predisposed to cancer do not form tumors.

Illnesses & ailments

Gene expression is a complex process that, like almost every genetic process in the body, can lead to disease. This applies both to the incomplete or absent gene expression and to the complete gene expression of defective genes.

In hereditary diseases of all kinds, there is gene expression of a dominant or a diseased recessive gene in connection with an equally recessive gene of the healthy parent. Hereditary diseases that do not break out in a diseased and a healthy gene are particularly insidious, because both parents are healthy, but are carriers of the diseased gene. If both diseased genes come together, there is no longer gene expression by a healthy and diseased gene or by the healthy, dominant gene, and the hereditary disease breaks out.

An example of this is hemophilia, which occurs almost exclusively in men. Genetically modifying substances that can alter gene expression in such a way that humans become ill or die are also considered dangerous. Radiation, for example, can change the structure of genes in every phase of human life so that gene expression is different from what it was before. This can lead to later development of cancer in adults and malformations in unborn children due to incorrect gene expression.

Similar effects of faulty gene expression due to external, mostly chemical influences are also observed in animals and plants, which change their color as a result or reproduce regenerative parts such as flowers and leaves differently than before.

A change in genes and thus deviations from the previous gene expression must also be ruled out with drugs; they must not have any so-called mutagenic effects on humans or animals. The thalidomide scandal is a negative example in this regard.