What exactly happens if during translation, an amino acid is not present?
Lets say that the cell wants to make a particular protein. Transcription of the appropriate gene is done and the mRNA is made. mRNA attaches to the ribosome and the translation is initiated in a "normal" way. What exactly would happen if an amino acid required in the protein is absent ? I know that the protein would not be manufactured properly but I want to exactly know what would happen to the ribosome and the mRNA. Are they destroyed? Are they simply separated? Who regulates this?
If the ribosome encounters a codon for which there is no matching aminoacyl-tRNA present, there are a few different possibilities as to what could happen. First, the translation machinery could stall, leading to "abortive termination". One recent paper showed that part of what leads to this termination is the following ribosomes colliding with the stalled one and kicking it off. (See: https://www.fredhutch.org/en/news/spotlight/2017/07/stalled-ribosomes-get-bumped-off.html )
Another possibility if an amino acid is missing is that the wrong tRNA is used and the wrong amino acid is incorporated. This is more likely when the third "wobble" position of the anticodon encodes for a different amino acid. Errors like this are rare, but may lead to diseases through protein mistranslation. (See: https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1008017)
