(lat.: transcribere = to rewrite)

Transcription means the copying of DNA information. Geneticists also talk about “reading” the genes. Why do genes have to be transcribed or read in the first place?

The genes are located on very long DNA threads. If the 46 DNA threads of one cell were to be rolled out and tied to each other, they would measure almost two meters. However, the cell nucleus is two hundred times smaller than a pinhead. Well-wound and well-folded, the DNA threads fit into the cell nucleus, but they do not fit through the very small channels which lead out of the nucleus through its shell.

The problem is that the protein factories of the cell are located outside the cell nucleus. So somehow, the blueprints for the cell’s components have to be brought out of the nucleus to the protein factories.

This is accomplished by transcribing the information from the long DNA thread onto the mobile messenger RNA. A “copying machine” scans the relevant section of the DNA and produces an exact copy of the gene’s succession of letters.

During this process, the usually twisted and rope-ladder-like DNA double helix is partially uncoiled. The two strands of the DNA rope-ladder which are usually bound together through two base letters as rungs are separated so that two single chains of gene letters are existent.

Now the copying device can determine the gene letters’ sequence and assemble a copy of the genetic text with RNA base letters. The copying device is called RNA polymerase because it ties together a transcript of the genes from many RNA pieces (Greek: poly = many, meros = part).