Question

In prokaryotic translation and transcription, what way does mRNA build and what way does it read? (ie 5' to 3')

Answer 1

Bacterial transcription is the method in which messenger RNA transcripts of bacterial genetic material are produced, get translated for the protein production. In prokaryotes, transcription as well as translation can occur simultaneously in the cytoplasm. RNA polymerase binds to the promoter sequences to initiate the transcription, during elongation RNA polymerase read the template in the 3' - 5' direction and build mRNA strand in 5' -3' by joining the 5'-PO₄^2-.of an incoming nucleotide triphosphate to the 3' OH of the precursor residue. Hence, during transcription RNA chain grows in the 5'-3' direction, same as replication.

Translation in prokaryotes:

At the starting of transcript, the assembly of ribosome takes place and initiate translation at the start codon AUG. first tRNA then binds that fits to the mRNA. The tRNA translocate in a manner that A-site shifts to the P-site so that next tRNA can bind.

Translation takes place always in the direction 5' -> 3'.

To identify the correct direction or starting point, the Ribosome not simply initiating at the mRNA 5`end. Before the AUG start codon, the mRNA consists of a untranslated, regulatory region, so-called 5'UTR. The end of prokaryotic 5'UTR consist of the so called Shine-Delgano sequence that is recognized by the ribosome. After mRNA binding, the sliding of ribosome takes place along the nucleotide chain until it hit the first AUG to start translation.