Final answer:
The trp operon in E. coli regulates translation through the use of a leader sequence called trpL. Different structures formed within the leader sequence determine if transcription will occur and if protein synthesis will take place. This regulation ensures that tryptophan synthesis only occurs when tryptophan levels are low in the cell.
Step-by-step explanation:
Translation regulation in E. coli is carried out through various mechanisms, one of which is the use of the trp operon. The trp operon contains a leader sequence called trpL between the operator and the first structural gene. The leader sequence has regions that can base pair with each other in different combinations, forming either terminator or antiterminator structures. When a terminator structure forms, transcription terminates and no protein is synthesized. On the other hand, when an antiterminator structure forms, transcription continues, allowing for protein synthesis. This regulation ensures that the synthesis of tryptophan, the final product of the trp operon, is only carried out when tryptophan levels are low in the cell.