Illustration of RNA (ribonucleic acid) polymerase transcribing DNA (deoxyribonucleic acid) to messenger RNA (mRNA). The RNA polymerase enzyme (centre) is shown traversing a section of DNA (double helix structure) producing a strand of mRNA (ribbon structure at upper left). To the right of the mRNA is DNA wrapped around proteins called histones (purple). Unwrapping of DNA from histones is required in order for transcription to proceed. Other structural proteins (yellow) are also shown below the RNA polymerase. The transcription of DNA to mRNA precedes the translation of genetic information into proteins which occurs in ribosomes (not shown).