DNA chains
grow in the 5' 
3' direction only
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, and the polynucleotide "grows" by modification of
the 3' end, in the 5'3' direction. Biochemical syntheses of nucleic
acids occur only in the 5'3' direction.
5' phosphodiester bond (R
- O - P - O - R). The original 5' end
remains unmodified, and the polynucleotide "grows" by modification of
the 3' end, in the 5'3' direction. Biochemical syntheses of nucleic
acids occur only in the 5'3' direction.Do not try to
understand this process in any other way!