大肠杆菌在葡萄糖和乳糖均丰富的培养基中优先利用葡萄糖而不利用乳糖，是因为此时阻遏蛋白与操纵基因结合而阻碍乳糖操纵子的开放。（）?
正确答案及解析
正确答案
正确
解析
乳糖启动子是弱启动子，必须同时有CAP来加强转录活性，CAP要与cAMP结合发生空间变化而活化。而当细菌内有葡萄糖代谢时，cAMP含量低。所以当乳糖和葡萄糖同时存在时，优先利用葡萄糖。
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