What is transcription in molecular biology?

Transcription in molecular biology refers specifically to the process of copying a specific segment of DNA into RNA. During transcription, the enzyme RNA polymerase binds to the DNA at a specific region called the promoter. It unwinds the DNA strands and synthesizes a single strand of messenger RNA (mRNA) using one of the DNA strands as a template. This means that the nucleotides of the DNA are converted to corresponding RNA nucleotides; adenine pairs with uracil (instead of thymine), and cytosine pairs with guanine.

The key aspect here is that this process is distinct from translation, where the information in the mRNA is used to assemble proteins, and from DNA replication, which involves copying the entire DNA molecule for cell division. This makes the understanding of transcription pivotal, as it represents the first step in the flow of genetic information from DNA to protein synthesis.