Final answer:
In prokaryotic elongation, an elongation factor, EF-Tu, hydrolyzes GTP to provide the energy needed for the next aminoacyl-tRNA to bind to the A site on the ribosome. After the binding, EF-Tu bound GDP is exchanged for GTP in preparation for the next cycle of elongation, facilitated by EF-Ts.
Step-by-step explanation:
In the process of elongation in prokaryotic cells, GTP hydrolysis provides the necessary energy for the binding of the next tRNA to the A site. This critical step is catalyzed by an elongation factor known as EF-Tu in bacteria (the equivalent is EF2 in eukaryotes).
Once the aminoacyl-tRNA is matched with the mRNA codon in the A site, GTP is hydrolyzed, and the energy released facilitates the accommodation of the tRNA into the ribosome.
Subsequently, the elongation factor bound GDP dissociates, and in preparation for another round of elongation, a separate elongation factor (EF-Ts in bacteria) helps to exchange the GDP for a new GTP on EF-Tu.
As elongation proceeds, the ribosome moves along the mRNA in a 5' to 3' direction, and the EF-G (prokaryotic translocase) catalyzes another round of GTP hydrolysis to move the ribosome forward and shift the tRNAs from the A site to the P and then to the E site.
Each cycle of elongation not only leads to the growth of the polypeptide chain but also consumes considerable energy in the form of GTP.