DNA Transcription (Advanced)


The central dogma of molecular biology; DNA makes RNA makes protein. Here the process begins. Transcription factors assemble at a
specific promoter region along the DNA. The length of DNA following the promoter is
a gene, and it contains the recipe for a protein. A mediator protein complex arrives
carrying the enzyme RNA polymerase; it maneuvers the RNA polymerase in to place, inserting it with the help of other factors
between the strands of the DNA double helix. The assembled collection of all these
factors is referred to as the transcription initiation complex,
and now it is ready to be activated. The initiation complex requires contact
with activator proteins, which bind to specific sequences of DNA known as
enhancer regions; these regions maybe thousands of base
pairs distant from the start of the gene. Contact between the activator proteins and the
initiation complex releases the copying mechanism. The RNA polymerase unzips a small portion of
the DNA helix, exposing the bases on each strand. Only one of the strands is copied; it acts as a template for the synthesis
of an RNA molecule which is assembled one sub-unit at a time by matching the
DNA letter code on the template strand. The sub-units can be seen here entering
the enzyme through its intake hole, and they are joined together to form the long messenger
RNA chains snaking out of the top.

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