Promoter sequences are specific sequences of the ribonucleotide bases making up the DNA strand (adenine, thymine, guanine,and cytosine), and the identity of several of these motifs have been discovered, including TATAAT and TTGACA in prokaryotes and TATAAAA and GGCCAATCT in eukaryotes. Promoter sequences on the DNA strand are vital for the successful initiation of transcription. The opposing strand is known as the partner strand. Following this, the DNA strand is denatured, uncoupling the two complementary strands and allowing the template strand to be accessed by the enzyme. Pre-initiation, or template binding, is initiated by the RNA polymerase σ subunit binding to a promoter region located in the 5’ end of a DNA strand. The production of mRNA from RNA in eukaryotes is particularly more complicated than it is in prokaryotes, involving several additional processing steps. In eukaryotes, DNA is stored in tightly packed chromatin, which must be uncoiled before transcription can occur. These differ in prokaryotes and eukaryotes in that DNA is stored in the nucleus in eukaryotes, and whereas DNA is stored in the cytoplasm in prokaryotes. Transcription occurs in four stages: pre-initiation, initiation, elongation, and termination. Three types of RNA can be formed: messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). DNA stores genetic information, which is then transferred to RNA in transcription, before directing the synthesis of proteins in translation. This is the first stage of protein production or the flow of information within a cell. In biology, transcription is the process whereby DNA is used as a template to form a complementary RNA strand – RNA is the “written” form of DNA. Transcription generally refers to the written form of something.
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