①5'→3'聚合酶 Incoming deoxynucleoside 5'-triphosphate 0=P-O 0 0=P-0 0 70 0=P-0 0=P-0 0 5'® Growing 3 O. 0=P0 DNA strand OHOH OH (primer) A 新生链 G T T Template DNA strand 模板链 3' (P5 61 Deoxyribose ① 5´ → 3´ 聚合酶 模板链 新生链