Radioactivity, nuclear waste, chemicals, harmful environmental influences – these and other terms accompany us through all media. In this context, there is sometimes talk of increased mutation rates (probability of mutation). But what exactly is a mutation, which mutations are there, and are mutations always only negative? We would like to give you a brief insight into the world of genes and chromosomes.
Definition of mutation
A mutation (Latin: mutare = to change) is a change in genetic material, the genotype. It can be a qualitative or quantitative change in the structure, but also in the effect of the hereditary factors. However: mutation is not equal to mutation. The following distinctions are made.
Coronavirus mutation: does SARS-CoV-2 change?
Affected cells
Somatic mutation: these are changes in all the cells of the body that have nothing to do with reproduction. These changes can be reflected in the growth and function of the cells. This gives rise to cancer, for example, and this type of mutation is also used to explain the aging process. This modification of the genetic material is “transferred” to subsequent cells in one’s own body, but cannot be inherited by offspring.
Generative mutation or germline mutation: mutations that occur in germ cells, that is, in eggs or in the cells that produce sperm, can be transmitted to offspring.
Structural viewpoints
Three types of mutations are distinguished here:
- Gene mutation or point mutation: a single small segment of information (gene) on a chromosome is changed. This is the result of spontaneous or environmental change (replacement, elimination, or insertion) of the base sequence of DNA (DNA = deoxyribonucleic acid; storage form of genetic material). There are endogenous mechanisms to repair the DNA, but it can also come to malfunctions.
- Genome mutation: change in the number of chromosome sets or chromosomes (carriers of genetic information). For example, the presence of 3 times instead of 2 times the chromosome 21 (trisomy 21) in humans leads to Down syndrome. Genome mutations play a major role in plant breeding. Yields can be increased by multiplying chromosome sets.
- Chromosome mutation: change in the shape and structure of chromosomes. These are triggered, for example, by chemical substances or ionizing radiation.
Mutations and selections as the cornerstone of evolution: Darwin’s theory.
“On the origin of species by means of natural selection” (in short: The Origin of Species) was the name of the book published by Charles Robert Darwin in 1859. It contained the results of his studies, which he described as follows: “Natural selection is the decisive factor in the evolution of species. Since the number of offspring is greater than is necessary for the preservation of the species, the result is a competitive struggle which only the adapted survive.”
Language ability through mutation?
Researchers recently reported in the British journal Nature on a gene (FOXP2) that, through mutation, may have enabled humans to communicate through language (Nature 418, 869 – 872).
Consequently, mutations can have both beneficial and detrimental effects on reproduction. Only when a mutation leads to a change in phenotype (trait pattern, appearance) does it become significant for selection.
