Elongation of the RNA transcript
The process is similar to that of DNA strand elongation: the
two termainal PO4 groups are clipped from the new
(ribo)nucleotide, and the 5' terminus is added to the old 3'
terminus. The ribonucleic acid growth thus occurs in the 5'-3'
Figure © 2012 TA Brown, Introduction to Genetics (1st ed.); additional text © 2012 by Steven M. Carr