Covalent structure ° long polymer chain ATPUTPGTPCTP 3-5 phosphodiester bonds(not 2-5) 5 -GUCATUATCCA-3Covalent structure • long polymer chain • ATP,UTP,GTP,CTP • 3’-5’ phosphodiester bonds（not 2’-5’） • 5’-GUCATUATCCA-3’