 Now no surprise this mess remember remind yourself this lovely Gorgeous ready for the party messenger RNA molecule is nothing more than a strand of Nitrogen bases. That's where the information is So this is where our RNA structure becomes relevant And we can see that here our RNA our rRNA Three dogs our RNA transcript has a Nitrogen base sequence and it looks just like DNA except for the presence of uracil in place of Thymine we don't have any teas in our messenger RNA, but we do have all the other bases somehow This transcript somehow the information in those bases in that sequence that very specific sequence of bases somehow that Codes for protein That somehow is the genetic code before I show you the genetic code I'm gonna write it down here Genetic code, so we don't forget that that's what we're aiming for Remember that we have four nitrogen bases. That's it, but we have 20 Amino asses it took 10 years for scientists working together to figure out how The sequence of nitrogen bases in this messenger RNA molecule coded for proteins 10 years of Collaboration sharing data adding from one person to the next person I don't even know how many scientists participated in this 10-year long process to decode The sequence of bases and figure out how that provides instructions for making proteins Because they went dude, there's four bases if each base corresponded with an Amino acid we'd only have four amino acids Then they're like dude. What if we had two? bases Code for one amino acid and you can do the math. I trust the math That would give you 16 Possible amino acids. It's not enough. So they actually figured out that the genetic code is based on codons Which are three bases three nitrogen bases make up a codon and one codon Codes for one amino acid now if you do the math on that if you have four possible bases and You put them in groups of three There are actually 64 possible Combinations that you can come up with 64 is way more than the 20 amino acids that we're going to code for which means there's some overlap Glory days that overlap Actually helps protect Against mutation and you can see that when we look at the genetic code. Are you ready? Don't get overwhelmed Cam ordering you not to get overwhelmed This is the genetic code now on the side of this thing. I've listed every amino acid on No planet would I ever Want you to remember the names of the amino acids? For me and my brain like I want to know what ALA in The genetic code chart that you also would never have to memorize I want to know that that's actually coding for the amino acid alanine ARG when I find ARG in this code chart. Oh cool. It's arginine. It's just an aside Here's my list of 20 amino acids and here's the code or the abbreviation that You are given This is the important part how this thing works Again Thank You Good World You will never have to memorize this and in any question any exam whatever I will have a copy of this for you I definitely encourage you to have a copy for yourself have access to this because you can decode Any strand of messenger RNA using this information? The one thing that I want to say is that the code we're looking for is messenger RNA I Could give you a DNA sequence and you could use this chart to Determine The amino acid that that DNA codes for but you'd have to do an extra step You'd have to take your DNA figure out what the RNA transcript is and then put the RNA transcript into This little chart here. Let me show you how it works. It's Glorious so clean and clear and easy Any code on any three letter Sequence of bases that are on a messenger RNA strand you figure out what the first letter is Let's say the first letter is a there it is Now you figure out what the Second letter is let's just say the second letter is C Track along. Oh, oops. That was a G. Sorry Track along. There's my C. I now know that My answer is somewhere in This box Do you agree with that? I went down from the C's and I went across from the A's and Let's I should have told you what the Whole code on was in the beginning. Let's say it's a CU Well, personally when I get the first two, I know what box to look in I don't bother looking at the third letter Because the third letter I'm gonna like there's not whatever There's no reason to go all the way over to the third letter column To find a CU when I can just be in this box and I can be like, oh, yeah, there's a CU A CU codes for the amino acid THR, which if we go look at it, that's threonine threonine this code this code on Will always code for threonine if the ribosome sees That code on the ribosome says hey, we need somebody to bring me a threonine That's the next thing to go into this protein sequence Holy crap. How do you feel about that? I could give you any sequence. You could tell me the amino acid that is coded for now. This is a really good example Obviously, I didn't plan ahead on this because I didn't know what codon I was going to use But this is a really good example of we could actually have a mutation We could have a mistake in the last base of the codon And it doesn't matter. We're still going to get the same amino acid that we asked for This is protective. This is good because it means that remember in the last section we talked or in the last lecture we talked about Six mistakes or one mistake for every billion copies you make Similar in transcription. We're gonna there's gonna be mistakes. There's gonna be Things that don't get done right and this is protective. So even if we had a replication mistake It doesn't matter because we're going to get the same amino acid as long as it happens in that one If it's the first one and there's all sorts of ways that mutations get super interesting Okay, that's the code. That's that's what the ribosome is going to Do That's the work that's going to happen in the ribosome. Are you ready to talk about Um, the ribosomes themselves That would be yes because you don't have a choice. That's what we're doing next