Final answer:
Antiterminators and repressors control lambda phage infection by regulating gene expression in E. coli. Repressor proteins bind to the operator DNA and block transcription of the operon in the absence of lactose. Antiterminators, on the other hand, prevent the formation of a terminator stem-loop, allowing RNA polymerase to continue transcribing the genes in the trp operon.
Step-by-step explanation:
The lambda phage infection of E. coli is controlled by antiterminators and repressors. The repressor protein, produced by the I gene, binds to the operator DNA and blocks transcription of the operon in the absence of lactose in the growth medium. However, when lactose is present, allolactose binds to the repressor and prevents it from binding to the operator, allowing RNA polymerase to transcribe the operon. In addition to repressors, antiterminators play a role in controlling lambda phage infection. Antiterminators are stem-loop structures formed within the mRNA being transcribed. When an antiterminator stem-loop forms, it prevents the formation of a terminator stem-loop, allowing RNA polymerase to continue transcribing the genes in the trp operon. This controls the expression of the trp operon in E. coli.