Transcription
Transcription is the transfer of the genetic information from the archival copy of DNA to the short-lived messenger RNA. The enzyme RNA polymerase binds to a particular region of the DNA and starts to make a strand of mRNA wiht a base sequence complementary to the DNA template that is "downstream" of the RNA polymerase binding site. When this transcription is finished, the portion of the DNA that coded for a protein, i.e. a gene, is now represented by a messenger RNA molecule that can be used as a template for translation.
The steps in transcription are:
- DNA unzips and RNA polymerase enzyme binds to one strand of DNA
- RNA polymerase makes an elongating chain of RNA nucleotides, each new RNA nucleotide complementary to the DNA nucleotide it is hydrogen bonded to
- The completed mRNA molecule is released from RNA polymerase - DNA complex and can begin translation. In eukaryotic cells this means first moving from the nucleus into the cytoplasm. In prokaryotic cells (bacteria), ribosomes can bind and begin translation before polymerase has completed of the new mRNA strand.
Our working diagram of this process is:
John Rueter 11/24/96