All living organisms must carry out protein synthesis, which has two main processes involved in it. Those two processes are transcription and translation. In the essay, I will go into depth about the process of transcription and its role in RNA. Transcription is assisted by sigma factors that encourage the RNA polymerase to bind to a specific site based on the environment. Polypeptide are enzymes which go on to act like the assembly machinery, breaking down and building and combining carbohydrates, lipids and proteins that make up variations of cell material. In the nucleus, DNA is transcribed onto an RNA molecule which is called a transcription unit. Each unit has a sequence just above it in the strand, this can be called "upstream". This sequence defines where the transcription unit will initiate. The special sequence just discussed is the promoter, which is a simple repetition that nearly always contains a sequence of two of the four nitrogen base pairs.
TATA box: a sequence that is rich in T=A. Upstream means toward the 3' end and downstream means towards 5'. RNA polymerase is the first enzyme in this process and it copies the DNA sequence towards the 5' end and copies into mRNA.
RNA polymerase binds to the DNA at the TATA box and starts to unzip the double helix. Working along the chain of DNA, the enzyme reads the nitrogenous bases and guides the RNA version of the nitrogenous bases that are floating around in the nucleus find their match. As the polymerase continues to work its way down, it rezips the DNA behind it and lets the new strand of the mRNA strip away. This continues until RNA polymerase is stopped by a sequence called termination signal. A termination signal triggers the RNA polymerase to pull off the mRNA strand.
Before mRNA can leave the nucleus it must undergo some finishing touches. First, a special type of guanine is added to the end of 5' – this is called the 5' cap.