RNA polymerase (RNAP) is a large complex (~400 kDa in bacteria); inertia and drag would hinder its rotation.
RNAP is attached to its RNA transcript, which becomes increasingly large as transcription proceeds thus increasing inertia and drag. Additionally, if RNAP were to begin to rotate around DNA, the transcript could begin to wrap around ...
Meaning of Motif in Molecular Biology
In English the word, motif (borrowed from the French), has a variety of meanings in different areas. The one that is borrowed in molecular biology is that of pattern together with a hint, perhaps, of emblem or badge.
The word pattern indicates both repetition and a master mould from which copies are made. In molecular ...
When they say "motif", do they mean that the gene PF1193 has a
subsequence which is found many times in the DNA sequence of the gene
that encodes ferritin- and Dps-like proteins ? And this may involve
that they have similar characteristics/properties ?
Yes, although motif sequences may not be exactly identical, as what really matters is the 3-...
It's a bit more complicated than that.
This wiki entry on nucleotides should help clarify things: Nucleotide
Diagram of chemical structure of bases, nucleosides, nucleotides, etc
I'm not sure what you mean by "...a range of functions..."