Hereditary material, genes, chromosomes

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

More posts by Christiane Fux All content is checked by medical journalists.

Whether humans, animals or plants: every living being carries its entire genetic make-up in every single cell. It is established at fertilization and is unique to each individual, with the exception of clones and a few twins.

A muscle cell contains information about the color of the eyes, just as a heart cell can contain a risk gene for Alzheimer's. However, only the genetic information that the cell needs for its function is active in every body cell. The other genes are shut down.

Chromosomes - 46 genetic packets

The genetic information is bundled in the chromosomes. Every healthy person has 46 of them, two of each kind - one from the father, one from the mother. In this way, the genetic make-up is mixed with ever new combinations. Two of the chromosomes determine the sex: while men have an X and a Y chromosome, women have two X chromosomes.

DNA - the genetic code

Chromosomes are long, thread-like structures that are located in the cell nucleus. They consist of deoxiribonucleic acid (DNA) or in English deoxiribonucleic acid (DNA). Basically, chromosomes are giant molecules that consist of only four different building blocks, the nucleotides. Each nucleotide is made up of a phosphate residue, the sugar deoxyribose and one of four organic bases: adenine, thymine, guanine and cytosine. The entire genetic code is composed of these four letters and their infinite possible combinations.

Each chromosome consists of two such long thread molecules that are coiled tightly like a ball of wool. They are linked to one another via the bases. Adenine and thymine, as well as guanine and cytosine, which are connected to one another via a hydrogen bridge, are opposed to one another. The structure of the DNA is comparable to a twisted rope ladder. The base pairs form the individual stages while the phosphate residue represents the lateral strands. This is how the famous shape of the double helix is created, which was first described in 1953 by the scientist duo James Watson and Francis Crick.

The genome - a code made up of more than 30,000 genes

The human genome is made up of three million base pairs and more than 30,000 genes. The genes only make up a fraction of the DNA strand. For most of the "rope ladder" the function is still unknown.

This also applies to most genes: the human genome was deciphered a few years ago. Most genes, however, are not yet known what their roles are.

On average, a gene comprises around 3000 base pairs. The genes serve as building instructions for proteins that have different tasks in the body. Proteins are not only building materials for body structures, but also take on tasks as messenger substances in the form of hormones, for example.

Blueprint of life

If a protein is to be built, the DNA strand splits at the relevant point like a zipper that is pulled open. Nucleotides attach to the open strands and form a new chain. Usually this is the messenger RNA (mRNA).

This process is called transcription. The mRNA is a mirror-inverted version of the gene, but instead of thymine it contains the base uracil. Instead of the sugar deoxyribose, ribose occurs in the RNA.

The mRNA strand migrates into certain cell structures, the ribosomes in them are constructed using the instructions for the specific protein. Geneticists call this process translation. All construction and remodeling processes in the body are based on it - the basis of all earthly life.