Rare bases HC HN HN N ON N HoN N N Ribose Ribose Ribose 4-Thiouridine(SU) Inosine (I) 1-Methylguanosine (m'G) CHs NH--CHo-CH-C CHs N HIN HIN Ribose HN H N O N Ribose H Ribose ribe Dose N -Isopentenyladenosine(i'A) Ribothymidine(T) Pseudouridine ( f) Dihydrouridine()Rare bases