After considering the DNA genes and RNA in the previous lesson, we are now ready to take a closer look at the process by which genes in the DNA lead to the creation of RNA or gene expressions. In fact, when we talk about genetic information, we refer either to genomic information, as represented in the DNA, or the transcriptomic information, as represented in the RNA, also called the transcriptome, or gene expressions. These are two sides of the same coin. Transcription is the process of producing the transcription from the genome. DNA contains all the information necessary to create new macromolecules such as proteins and beyond new human beings. In other words, the DNA encodes the data representing the blueprint of a particular person. The process by which DNA is transcribed into corresponding RNA proceeds through a series of steps, much like a cooking recipe can be used to create a new dish. The analogy with a computer program is even stronger, where the DNA represents the data, as a biological process of transcription represents a computer program. More precisely, transcription evolves through four steps. First initiation, a DNA macromolecule opens and an enzyme called RNA polymerase binds with the promoter of the template strand. Second step is elongation, the RNA polymerase processes each nucleotide on the DNA template strand to produce an mRNA, a messenger RNA. The third step is termination, transcription stops either when meeting a Rho protein factor or a loop at the end of the DNA strand. The first step is processing, the newly created mRNA macromolecule is processed by removing the introns, the non coding sequences, and slicing the exons, coding sequences, together so that only regions coding for proteins are maintained. This picture illustrates a process. We see the DNA being partially opened by the RNA polymerase, and the new nucleotides being created matching the original DNA nucleotides following an order three prime to five prime, or five prime to three prime. During the transcription process, mRNA nucleotides are synthesized following a very strict process: DNA A to mRNA U, DNA T to mRNA A, DNA G to mRNA C and DNA C to mRNA G. It is like translating words between languages,. Here is a transcription example, given the sequence: 5'-CTGAATCGAT-3'. The mRNA sequence transcribed from this DNA sequence Is obtained by substituting the nucleotides following the rule C to G, G to C, A to U and T to A,, which yields GACUUAGCUA. Also orientation can be either 5' -3' or 3' -5' since the DNA in the first place is the double stranded. In the end, just go look at the video which is a 3D representation from the DNA Learning Center. It's a resource that will illustrate what we have seen through words and through static images in a 3D animation.