How Transcription Works: DNA to mRNA Explained Visually

DNA transcription begins with the unwinding of the DNA double helix.Special proteins called helicases attach to the DNA and begin to unwind the strands.As the DNA unwinds, a section of the double helix separates, exposing the template strand.RNA polymerase recognizes and binds to the promoter region of the gene.This creates a transcription bubble where the DNA strands remain separated.The enzyme positions itself to read the template strand in the three prime to five prime direction, while building the messenger RNA in the five prime to three prime direction.The transcription machinery is now ready to begin synthesizing messenger RNA.RNA polymerase moves along the DNA template strand, reading the sequence and adding complementary RNA nucleotides.The enzyme follows specific base pairing rules, where Adenine pairs with Uracil instead of Thymine, and Guanine pairs with Cytosine.As RNA polymerase moves, it catalyzes the formation of phosphodiester bonds between nucleotides, creating a growing RNA strand.This process continues steadily at a rate of about forty nucleotides per second, efficiently creating the messenger RNA strand.As RNA polymerase approaches the termination sequence, the final phase of transcription begins.When RNA polymerase reaches the termination sequence, it triggers a series of events that will end transcription.The newly formed messenger RNA strand detaches from both the DNA template and the RNA polymerase.The DNA double helix reforms behind the transcription bubble, returning to its original structure.The completed messenger RNA molecule is now free in the nucleoplasm, ready for further processing before leaving the nucleus.In eukaryotic cells, this messenger RNA will undergo additional processing before it can leave the nucleus and be used for protein synthesis.