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transcription

noun

It is the process of transcribing or making a copy of genetic information stored in a DNA strand into a complementary strand of RNA (messenger RNA or mRNA) with the aid of RNA polymerases.

Although RNA polymerase traverses the DNA template strand from 3' → 5', the coding (non-template) strand is usually used as the reference point. Hence, the process proceeds in the 5' → 3' direction, like in DNA replication. However, unlike DNA replication, transcription does not need a primer to start and it uses base pairing to create an RNA copy containing uracil instead of thymine.

In prokaryotes transcription occurs in the cytoplasm whereas in eukaryotes it takes place primarily in the nucleus before the mRNA is transported into the cytoplasm for translation or for protein synthesis.