献媚 xiàn mèi

为讨好别人而做出使人欢心的姿态、举动。



老爷翰苑蜚声，素羨风流太守；贱妾平康献媚，自惭窈窕佳人。　　明 陈汝元《金莲记·湖赏》

有欲私其仆妇者，仆固黠，令其妻献媚勾引，而终不一任缱绻，主急甚。　　清 采蘅子《虫鸣漫录》

卷二她不想用鲜花向主人献媚，遍身披上刺刀。　　流沙河《草木篇》诗

operon

The lac-operon consists of a operator, gene Z, gene Y, and Gene A.

The repressor protein will be able to bind onto the operator side. After binding onto the operator side, the RNA polymerase will not be able to proceed to read the DNA, and therefore, the DNA will not be transcripted.

In order for the RNA polymerase to be able to transcript the DNA, the lactose will bind onto the repressor, and therefore changing the shape of the repressor, and it will no longer be able to fit onto the operator.

After that, the RNA polymerase is able to proceed into transcripting the DNA without any obstacle blocking.

After transcription, it will form mRNA, and then it will form protein. The gene A codes for beta-galactosidase, which is able to break down lactose to form glucose.