 Morpholinos are synthetic molecules that are the product of a redesign of natural nucleic acid structure . Usually 25 bases in length , they bind to complementary sequences of RNA by standard nucleic acid base @-@ pairing . In terms of structure , the difference between Morpholinos and DNA is that , while Morpholinos have standard nucleic acid bases , those bases are bound to morpholine rings instead of deoxyribose rings and linked through phosphorodiamidate groups instead of phosphates . This may be easiest to visualize by referring to the first figure and comparing the structures of the two strands depicted there , one of RNA and the other of a Morpholino . Replacement of anionic phosphates with the uncharged phosphorodiamidate groups eliminates ionization in the usual physiological pH range , so Morpholinos in organisms or cells are uncharged molecules . The entire backbone of a Morpholino is made from these modified subunits . 
