Mutations: changes in the genetic material

In short: A mutation is a lasting change in the genetic information, that is, in the sequence of building blocks in the DNA. It may have no consequences, cause diseases or, rarely, even bring advantages.

In more detail: Mutations arise all the time, for example through errors when DNA is copied or through external influences such as UV radiation. Cells have repair systems that fix most of the damage, but not all of it.

In detail

• Point mutation: A single DNA building block is swapped for another; sometimes this changes nothing, sometimes a different protein building block or a premature stop signal results.
• Insertion and deletion: If building blocks are added or lost, the reading frame can shift, so that from that point on the whole blueprint for a protein is altered.
• Chromosomal mutations: Larger sections of a chromosome can be lost, duplicated, reversed or attached to another chromosome.
• Genome mutations: Here the number of chromosomes is changed; a well-known example is trisomy 21, in which chromosome 21 is present three times instead of twice.
• Causes: Besides spontaneous copying errors, high-energy radiation, UV light and certain chemicals, for example in tobacco smoke, can damage the genetic material; such influences are called mutagens.
• Body cells and germ cells: Mutations in body cells affect only the individual and can, for example, contribute to cancer; only mutations in egg or sperm cells are passed on to children.
• Consequences for health: Even a single altered building block can cause a hereditary disease, such as sickle cell disease, in which the red blood pigment is changed.
• Engine of evolution: Many mutations are neutral, and a few bring advantages under certain conditions; they are the basis of the variety on which natural selection acts (chromosomen-und-karyotyp, proteinbiosynthese-einfach-erklaert, evolution-grundlagen).