RNA replication （RNA 复制）

★RNA virus:  Viruses need an RNA-dependent RNA-polymerase (RDRP) to replicate their RNA, but animal cells do not seem to possess a suitable enzyme. ——RNA 复制酶为RNA病毒复制所需

RDRP: no primer and no proofreading function.

RNA 病毒的复制

★正单链RNA病毒：

 the same as mRNA and functions as mRNA .

★负单链 RNA 病毒：  

 complementary to mRNA and need to be copied toplus-sense mRNA.

★双链 RNA 病毒：

cannot function as mRNA and need RDRP.

                                 RNA synthesis in viruses

Summary

★原核生物主要为1种RNA聚合酶催化RNA合成; 真核生物有3种RNA聚合酶催化不同RNA的合成. 

★RNA转录过程分为: 起始; 延长; 终止

★RNA 转录后加工: 5’; 3’; 剪接; RNA 编辑; 碱基修饰.