一、考点分析考点指要名师预测第1题图一是将某细菌的基因A导入大肠杆菌内,制备“工程菌”的示意图。下表中列出了几种限制酶的识别序列及其切割位点,A、B中箭头表示相关限制酶的酶切位点。请据图回答:(1)目的基因可以从___中获取,也可以利用化学方法人工合成。利用PCR技术扩增目的基因时,需要在反应体系中添加的 First, the test center analysis refers to the teacher to predict the first question Figure 1 is a bacterial gene A into Escherichia coli, the preparation of “engineering bacteria” schematic. The identification of several restriction enzymes and their cleavage sites are listed in the following table. Arrows in A and B indicate restriction sites for the relevant restriction enzymes. According to the figure to answer: (1) the purpose of the gene can be obtained from ___, can also be synthesized by chemical methods. PCR amplification of the target gene needs to be added to the reaction system