What is a mutation?

Radioactivity, nuclear waste, chemicals, harmful environmental influences – these and other terms accompany us through all media. In this context, there is some talk of an increased mutation rate (probability of mutation). But what exactly is a mutation, which mutations are there, and are mutations always negative? We want to give you a brief insight into the world of genes and  chromosomes  .

Definition Mutation

A mutation (Latin: mutare = to change) means a change in the 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 the same as mutation. The following distinctions are made.

affected cells

Somatic mutation:  These are changes in all the cells of the body that are not related to reproduction. These changes can affect cell growth and function. This  causes cancer , for example, and this form 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 the germ cells, i.e. in egg cells or in the cells that produce sperm, can be passed on to offspring.

structural aspects

There are three types of mutations:

• Gene mutation or point mutation:  A single small piece of information (gene) on a chromosome is changed. This is the result of spontaneous changes or changes caused by environmental influences (exchange, elimination or insertion) in the base sequence of the DNA (DNA = deoxyribonucleic acid; storage form of the genetic material). There are endogenous mechanisms for repairing DNA, but malfunctions can also occur here.
• Genome mutation:  change in the number of chromosome sets or chromosomes (carrier of genetic information). For example, the 3-fold instead of 2-fold presence of 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 the chromosome sets.
• Chromosome mutation:  change in the shape and structure of the chromosomes. These are triggered, for example, by chemical substances or ionizing radiation.

Mutations and selections as cornerstones of evolution: Darwin’s theory

“On the origin of species by means of natural selection” (kurz: Die Entstehung der Arten) hieß das Buch, das Charles Robert Darwin im Jahre 1859 veröffentlichte. Es beinhaltete die Ergebnisse seiner Studien, die er wie folgt beschreibt: “Die natürliche Zuchtauswahl ist der entscheidende Faktor für die Entwicklung der Arten. Da die Zahl der Nachkommen größer ist als zur Arterhaltung erforderlich, ergibt sich ein Konkurrenzkampf, den nur die Angepassten übers tehen”.

Sprachvermögen durch Mutation?

Forscher berichteten kürzlich in der britischen Fachzeitschrift “Nature” über ein Gen (FOXP2), das durch Mutation den Menschen möglicherweise dazu befähigt hat, sich durch Sprache zu verständigen (Nature 418, 869 – 872).

Mutations can thus have both beneficial and detrimental effects on reproduction. Only when a mutation leads to a change in the phenotype (characteristics, appearance) does it become significant for selection.