Every living creature has a hereditary substance, the genom, which contains the totality of the genes for all the functions of an organism. The "scaffolding", which carries the hereditary information is internationally known as DNA (=Desoxyriboribo-Nuclein-Acid). It is contained in very cell of body as part of the cellular core. You can imagine a spiral, long and complex structure. The hereditary information on the DNA is spread over different parts, every one containing one specific information. These parts are the genes (from Greek "genos" = descent, origin, gender, kind). One gene therefore contains some partial information for some specific attribute. One gene or a group of genes will decide on how clearly marked one or several of the attributes will be. The sum of all the genes - i.e. the genetic information of an organism - is called a "genom". The genes will be found at the core of the cell and lie there "on the chromosomes", i.e. rod shaped forms. A bacterium only has one chromosome, which has the form of a closed ring and contains about 2'000 genes. The whole hereditary information of a human being with his or her 60 billion cells and 46 chromosomes contains about 100'000 genes.

The DNA can only be discerned with the help of on electronic microscope.