上游充通大学 1 A Nucleic Acid Consists of 4 Kinds of Bases SHANGHAI JIAO TONG UNIVERSITY Linked to a Sugar-Phosphate Backbone 核酸骨架（2种)： base base base 核苷酸 脱氧核糖核酸 5 12 DNA base base base 核糖核酸 OH OH 5 3 2 H2 RNA 磷酸二酯键 Figure 4.3 Backbones of DNA and RNA.The backbones of these nucleic acids are formed by 3'-to-5'phosphodiester linkages.A sugar unit is high-lighted in red and a phosphate group in blue1 A Nucleic Acid Consists of 4 Kinds of Bases Linked to a Sugar-Phosphate Backbone Figure 4.3 Backbones of DNA and RNA. The backbones of these nucleic acids are formed by 3' -to-5' phosphodiester linkages. A sugar unit is high-lighted in red and a phosphate group in blue 磷酸二酯键 核苷酸 核酸骨架（2种）： 脱氧核糖核酸 核糖核酸