What are the three stages of transcription?
Transcription is the process of synthesizing RNA (mRNA, tRNA, and rRNA) from a
DNA template. This process is catalyzed by an enzyme called RNA polymerase.
There are three stages of transcription: initiation, elongation, and termination.
Initiation is the first stage, where RNA polymerase (in association with other proteins
called transcription factors) binds to a specific sequence on the DNA, known as the
promoter region. Once the RNA polymerase is securely bound to the promoter, it
begins unwinding the DNA helix and initiating the formation of the RNA transcript.
Elongation is the second stage, where the RNA polymerase adds nucleotides to the
growing RNA chain. As the RNA polymerase moves along the DNA template, it
unwinds the double-stranded DNA and adds RNA nucleotides, complementary to the
DNA template. The RNA transcript grows longer until the RNA polymerase reaches
the final signal or terminator sequence.
Termination is the final stage, where the RNA polymerase encounters the terminator
sequence, leading to the release of the newly synthesized RNA transcript, RNA
polymerase, and other transcription factors from the DNA template.
In conclusion, transcription is a vital process in gene expression and involves three
stages - initiation, elongation, and termination. By understanding these stages, we
can better appreciate the intricate and regulated nature of gene expression.
References:
1. Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & Walter, P. (2002). Molecular
Biology of the Cell. New York: Garland Science.
2. Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., & Darnell, J. (2000).
Molecular Cell Biology. New York: W. H. Freeman.