How are nucleic acids broken down?
Nucleic acids are broken down by nuclease enzymes which break the phosphodiester bond between two nucleiotides. There are endo- as well as exo-nucleases.
Deoxyribonuclease (DNase) and ribonuclease (RNase) are exonucleases found in our pancreatic juice. These enzymes break down nucleic acid molecules present in our diet by cutting away nucleiotides from one end.
Endonucleases on the other hand cut a nucleic acid molecule to form smaller fragments. Restriction enzymes are all endonucleases : but these enzymes cut DNA only at palindromic sequences. Specific restriction enzyme always recognizes only one such unique sequence.