In the production of a protein molecule, there have to be a ready supply of free-floating amino acids. When a given codon for adjoining, say, serine comes up, how are the serine molecules found out of a soup of 20 different types of amino acids?
Meleagris gallopavo (turkey) small muscular protein NCBI Reference Sequence: XP_010724014.1 88aa GI: 733873411 1 mskqpashvk aiqaninipm gafrpgaghp hkrkevtpee veesvpatee ekdkkhlpga 61 iklpgpavnl seiqniksel kfvpkaeq
has 9 alanines, 1 aspartate, 11 glutamates, 2 phenylalanines, 5 glycines, 4 histidines, 6 isoleucines, 11 lysines, 4 leucines, 2 methionines, 4 asparagines, 10 prolines, 4 glutamines, 2 arginines, 5 serines, 2 threonines, 6 valines, 0 tryptophans, 0 cysteines, 0 tyrosines.
So the cell would deplete glutamates much faster than aspartates and obviously infinitely faster than tryptophans. So, as the concentration of glutamates drops drastically with the production of each new turkey muscle polypeptide strand, getting diluted by the nonreactants tryptophan, cysteine, tyrosine, wouldn't the reaction rate get exponentially slow?
And when the last available glutamate residue gets attached, and if it happens before the polypeptide is complete, yet it needs one more glutamate to complete the chain, what signals the ribosome to "stop looking for more glutamates"?