Sometimes I'll catch the strangest research obsessions. Right now it's ribosomes. Still can't find a reasonable explanation for what energy system drives the mRNA through the translation process or draws in the tRNA. Brownian indeterminacy, is that a thing? Free energy?
Two separate helper proteins assist with bringing the tRNA in (EF-Tu / eEF1A) & the translocation step where the ribosome “ratchets”, shifting the mRNA & tRNAs over 1 step (EF-G / eEF2). Each depends on a conformational change in the helper protein triggered by GTP hydrolysis to GDP + phosphate.
So basically the same energy as ATP, which you may have heard of, but a slightly different molecule as an intracellular token to keep the whole thing moving at each step. The other costly bit is actually making the peptide bonds—that energy also comes from bond breaking (between tRNA & amino acid).
Thank you so much for responding! I see animations depicting chains of mRNA 'swimming' around... I get the chemical reaction energy, but still not grasping the source of locomotion within the cytoplasm.
Oh yeah, bringing all the bits together is more of a Brownian motion thing I believe, with the caveat that cytoplasms are actually pretty damn crowded. Perhaps a biophysics person can chime in! Your question got picked up on the #RNAbiology feed which is how I saw it! 🙂