 There's two guys that we need to talk about before we get to going through the whole process of translation and the two people are TRNA molecules and The ribosome We're gonna look at the structure of the ribosome so that we have just some context for the parts that we're gonna be talking about when we deal with the actual process of translation and Remember in the last one when I said in the genetic code chat. I said The ribosome uses this genetic code chart to say hey the mRNA says ACU I need someone to bring me a threonine Guess who does that guess who transfers the amino acid to the ribosome. That's TRNA TRNA is a strand of RNA and remember how we talked about DNA is a double-stranded molecule, but RNA is a single-stranded molecule Take a look at this mess. What even is that? That's one string of RNA That folds into a certain shape and this shape has two really really really important parts One part is called and I just I'm oh My gosh, do you guys know how much I love this stuff? It's so freakin cool this part aka this part in our picture in our folded weird image of the 3d Shape of a TRNA molecule. Did I say that that's transfer RNA? That's what the t stands for This is called the anti codon What? It's three bases and it matches the codon Okay, look, let's use the mRNA codon ACU so if the codon is ACU Then tell me what's the anti codon? Gonna be The anti codon is gonna bind to the codon. It's gonna match the codon It's not ACU because that won't match who matches to a Well in my brain since we just did DNA replication I go like dude It's t a's and t's go together, but you know that in RNA. We don't have t's we have use So the anti codon has a you To bind to the a who binds with C G So the anti codon has a G and who binds to you I'd be like dude. What you I don't know except. Oh, yeah, you replace this t which means it must be a Do you follow how I got that? So my anti codon in this case if we were gonna make this the t RNA that carries threonine It's anti codon is gonna be you G a now Do not take your anti codon back to this chart to determine what amino acid it's carrying This chart is for messenger RNA only be sure to take the messenger RNA codon back, but What amino acid is this carrying? This is the second important part. There's an amino acid connection I'm sure this has a better name Then amino acid connection zone but it's that Amino acid connection zone binds to threonine only It doesn't bind to leucine. It doesn't bind to glycine. It doesn't bind to arginine It binds to threonine only and So the anti codon binds to the codon that's coding for threonine That's how The ribosome gets the correct amino acid that's necessary for this process, dude Should we just like give kisses and love to our t RNA molecules? That's just wild there are 64 Different t RNA molecules. So in this place where we're like, dude, there's four codons that code for threonine That means there are four possible t RNA molecules out there all of them holding threonine and then there's the one that is There are all the 64 others that are coding for the other amino acids. How do you feel? That was just the first player that we wanted to bring in and talk about before we get into the process of protein synthesis The second player is the ribosome itself The ribosome has two subunits and It actually like I always think of a ribosome is just a tiny little dot in a cell And that's because that's how it's always depicted in pictures of cells when you learn the ribosome It's all those little dots in there. They're not hollow. They're just like these solid little dots Well, they're made of messenger. I mean of ribosomal RNA. Let's write that down r RNA is and proteins and some proteins and They're built Remember, where are they put together? They're built in the nucleolus. I don't know why I think that's so cool So the nucleolus that dot inside the nucleus is In there building ribosomes like mad because you need a lot of them But they have these two subunits and the subunits don't come together until you have a messenger RNA molecule with It's five prime cap the only thing I'm gonna tell you here is that Once the ribosome Connects so it has its big subunit and its little subunit and they're connected the ribosome itself has three binding sites for tRNA molecules So you have the A site the P site and the E site and I see that this diagram that I've chosen tells you the names of the sites, but I'm gonna tell you The way I remember the A site P site and E site E site is easy and they agree with me. It's the exit site. That's how like I literally think Exit so that's the last place that the tRNA molecule is gonna be before it bounces The P site I think of it as the protein site This is the place where I'm building my protein. I in the P site if everything pauses I should have a string of amino acids growing and The A site I think of it as the amino acid site or the arrival site So this is the place where the amino acid arrives to the set the next amino acid arrives to the A site This means that we're actually progressing in this direction So a tRNA molecule Arrives at the A site moves to the P site and gets attached to the growing peptide and Then leaves at the E site How do you feel about that? Pat your ribosomes too. I didn't get as excited about the ribosomes as I did the tRNA molecules But I am as excited because in the next piece we get to walk through the whole process of translation