Formation of a 3'-5' phosphodiester
bond in DNA synthesis
During DNA
synthesis, new
nucleotides
are added to the existing 3' end, by a 3'-5'
phosphodiester bond (R - O - P - O
- R). The original 5' end remains
unmodified. Polynucleotides thus "grow" at the 3' end,
in the 5'
3' direction. Nucleic
acid biochemical processes occur only in
the 5'3'
direction.
Figure © 2000 by Griffiths et al. ; text © 2007 by Steven M. Carr