DNA Transcription (Advanced Detail) | HHMI BioInteractive Video


SPEAKER: 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
arise, carrying the enzyme RNA polymerase. It maneuvers the RNA polymerase
into 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 may be 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 subunit at a time by matching the DNA letter
code on the template strand. The subunits can be seen
here entering the enzyme through its intake hole. And they are joined together
to form the long messenger RNA chain snaking out of the top.

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