RNA polymerase, the enzyme that transcribes the genetic code

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RNA polymerase, the enzyme that transcribes the
genetic code Human body more than 200 cell
types, all have same DNA Different cell types
because differences in gene expression patterns
in time and space. Central Dogma of Molecular
Biology flow of genetic information from DNA
(genes) to messenger RNA to enzymatically
functional proteins. RNA Polymerase (RNAP) is
the enzyme responsible for the first step in gene
expression -- the DNA-directed synthesis of RNA
-- known as transcription.
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During transcription RNAP powered by the free
energy released by nucleotide polymerization. RNA
P moves along DNA template at speeds greater than
10 nucleotides per second. RNAP can support
forces greater than 20pN These large forces
allows RNAP's to displace bound proteins, such as
histones, that it encounters as it transcribes
along the DNA template. Ability to convert
chemical energy into motion is similar to that of
other motor proteins such as myosin and kinesin.
Major consideration for differential gene
expression RNAP moves along DNA -- a
heteropolymer, not homopolymers such as muscles
actin or microtubules RNAP regulated by
extrinsic protein factors (lac, sigma, GreA/B,
rho, etc.), but also by signals encoded within
the DNA template (Ia- an arrest site in human
histone genes) or RNA (trp terminator sites).
This extra degree of regulation makes RNAP an
exquisitely controlled protein.