Gene Expression: Function, Tasks, Role & Diseases

Gene expression refers to the expression and development of a genetically predisposed characteristic of a living being. This is contrasted with genetic information that is not expressed and can only be detected by DNA analysis.

What is gene expression?

Gene expression refers to the expression and development of a genetically predisposed trait of a living being. Every living thing has a large number of genes, but not all of the traits contained in the DNA are ever expressed, that is, expressed. Some genes remain inactive but are present and can still be inherited. Depending on the genotype of the sexual partner, an unexpressed gene may appear, i.e. be expressed, in the generation of offspring. In gene expression, there are always two identical genes in question, one from the mother and one from the father, which are in competition with each other to a certain extent. There is a dominant and a recessive gene. In humans, a dominant gene usually “wins” over a recessive one, or else two recessive genes are expressed equally and result in a visible trait that lies between that of the mother and father. In some plants, for example, the colors red and white are both recessive, for example, and pink flowers are produced in the offspring generation when they are mixed, because there is gene expression of both genes.

Function and task

Humans have a large number of genes on their total of 47 pairs of chromosomes. Like every living being, he has one half from his mother, the other half from his father. From the point of view of evolutionary biology, it is now a matter of expressing those genes that are most helpful for the survival of the new human being. For example, in the course of evolution it turned out that gene expression of the genes for dark skin in sunny-warm areas of the earth was an advantage for humans, while gene expression of the genes for light skin was better in less sunny parts of the earth. Especially in the case of two recessive genes, it leads to the fact that one of the two or also a mixed form can be expressed by the gene expression, whereby the species is able to continuously improve and become more survivable. Therefore, even genetically identical monozygotic 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 caused by the constant formation of new body cells, have always occurred in almost every multicellular creature. This is how, for example, snow hares or polar bears came into being: gene mutation led to the development of white hair gene expression, the mutated animals proved to be more survivable in polar regions than their brown conspecifics 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 to become widespread. For humans, it is not only the gene expression of their own body that proves useful, 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 cause the failure of vital functions. The bacterium dies and the person can recover from bacterial infection. Furthermore, research is underway to determine whether cancer-causing genes can be inhibited in their gene expression so that people genetically predisposed to cancer do not form tumors.

Diseases and disorders

Gene expression is a complex process that, just like almost any genetic process in the body, can also lead to disease. This applies to both incomplete or absent gene expression and complete gene expression of defective genes. Inherited diseases of all kinds result in the gene expression of a dominant or a diseased recessive gene in combination with a likewise recessive gene of the healthy parent. Particularly treacherous are hereditary diseases that do not break out in the case of one diseased and one healthy gene, because this means that both parents are healthy but carriers of the diseased gene. If both diseased genes come together, gene expression by a healthy and diseased gene or by the healthy, dominant gene no longer occurs and the hereditary disease breaks out. An example of this is hemophilia, which occurs almost exclusively in males.Genetically altering substances that can change gene expression in such a way that a person becomes ill or dies are also considered dangerous. Radiation, for example, can alter the structure of genes at any stage of a person’s life in such a way that gene expression is different from before. This can lead to the later development of cancers in adults and malformations in unborn children as a result of incorrect gene expression. Similar effects of incorrect gene expression due to external, mostly chemical influences are also observed in animals and plants, which change their color as a result or reproduce regrowing 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 in the case of medicines; they must not have any so-called mutagenic effects on humans or animals. The thalidomide scandal represents a negative example in this respect.