In studies using repeating copolymers, AC . . . incorporates threonine and histidine, and CAACAA . . . incorporates glutamine, asparagine, and threonine. What triplet code can definitely be assigned to threonine?

Video transcript

Hi everyone, Welcome back. Let's look at our next question. It says which of the following genetics genetic codes is not recognized by any T. R. N. A. In a human cell. Well, to answer this question, we want to think about what would make a genetic code not recognized by A T. R. N. A. And the answer is that that would be if it's a stop code on the T. RNA is only recognized cardin's for amino acids. The stop code ons are not recognized by any T. RNA. Instead they're recognized by release factors which bind that stop coat on and caused the release of the newly formed poly peptide. So we need to look at our answer choices and find the one that's a stop code on. Well there's a funny little pneumonic for remembering the stop code ons. There's three of them in humans. And they are you A U G. A. And you A G. And the way to remember those. You think of a stop code on as something that's you know ending translation and sending away the protein. You A think of you are annoying U. G. A. You go away you A G. You are gone. So if you think of those three things can help you remember those three stop code ons. So when we look at our answer choices, we see that choice B here is U. G. A. Which is one of our stop code ons. None of the others are stop are one of those three stop code ons. But let's say we can't remember that off the top of our head Then we want to look up on a code on chart These four code ons to find the stop code on. Put that up there and we see that our first choice A. Is a U. G. So we come along here, first letter over here, a second letter showing it's in this column. And then we look for they're in the order of you see a G. As we go down in the box. So we're looking for a U. G. We've got that here and that's going to be methane in. So not what we're looking for. We're gonna cross that out next B. We know that's a stop code on and see if we can confirm that over here. If we look up you G. A stop code on, then we go to choice C. A. G. G. Look along here A. G. G. That's gonna be the amino acid arginine. So not our answer. That would be recognized by T. R. N. A. And then finally Choice D. U. U. U. Up here, that's phenylalanine. So not our answer choice. So again, which of the following 10 of the codes is not recognized by any T. R. N. A. And that's choice B. U. G. A. See you in the next video