During transcription, the genetic information encoded in a specific segment of DNA is copied into a complementary strand of messenger RNA (mRNA). This process occurs in the nucleus of eukaryotic cells and involves several key steps:
- Initiation : RNA polymerase, the enzyme responsible for transcription, binds to a specific region on the DNA called the promoter. This binding signals the DNA to unwind, exposing the template strand for reading
- Elongation : RNA polymerase moves along the DNA template strand, adding RNA nucleotides that are complementary to the DNA bases-adenine pairs with uracil (in RNA), cytosine with guanine, and so forth. This builds the growing mRNA strand in the 5′ to 3′ direction
- Termination : When RNA polymerase reaches a termination sequence on the DNA, transcription stops, and the newly synthesized mRNA strand is released
The mRNA molecule produced is complementary to the DNA template strand but contains uracil instead of thymine. After transcription, the mRNA exits the nucleus to the cytoplasm, where it serves as a template for protein synthesis during translation
. Transcription is facilitated by transcription factors that help recruit RNA polymerase to the DNA and form a transcription initiation complex. This complex ensures the correct start site and efficient synthesis of mRNA
. In summary, transcription is the process of copying a gene's DNA sequence into an RNA molecule, primarily mRNA, which carries the genetic instructions necessary for protein production
