Final answer:
Translation of downstream genes can continue in the presence of a stalled upstream ribosome in attenuation through the re-initiation of translation in the 3' UTR of the mRNA. Riboswitches, which are secondary structures in the 5' end of the mRNA being transcribed, can control the completion of transcription and translation. This mechanism allows for the regulation of gene expression even in the presence of a stalled ribosome.
Step-by-step explanation:
In attenuation, riboswitches are secondary structures formed in the 5' end of an mRNA being transcribed. They can regulate gene expression by controlling the completion of transcription and translation of downstream genes. Even if the upstream ribosome stalls, the translation of downstream genes can continue because the ribosome can re-initiate translation in the 3' UTR of the mRNA. This re-initiation can occur using AUG codons upstream of the normal start codon, and there is evidence that these short polypeptides produced can still have functional roles.