tRNA, rRNA and the Codon Code - Video Tutorials & Practice Problems

Codon Code

Hi in this video we're gonna be talking about T R N A R R N A. And the code on code. So even though the code on code has mentioned last in the title, we're actually going to talk about it first. And so the reason we need to talk about the code on code is because of translation. And so what is translation again? Translation is the process of going from D. N. A. To protein. And so how do we do that? And what are the terms that we use to describe this process and what's needed for translation to occur? So in order to explain these in these terms to you, I'm going to keep coming back to this example. And the example is this is if I was trying to translate a set of texts, a paragraph for instance from english to spanish, what would I need to know? Well I would need to know words right I would need to know care characters. Is the spanish use the same alphabet as english or is it a different alphabet? And what kind of rules are there? So that I know how to take one english word and what the meaning of that is in spanish. So we need a dictionary, we need to know something about grammar, how the sentences are formed, how the paragraph is formed and the same thing. All of this is also needed for translation from DNA to protein. But instead of talking about it in terms of paragraphs and sentences and words and characters. So A B C D. We're gonna I'm gonna introduce the terms that we have to talk about translation from DNA to protein. And so the first thing is that translation? Yes it goes from DNA to protein. But what is it actually doing? What it actually is doing is it's taking combinations of nucleotides. So A. T. C. And G. And changing them to amino acids, translating them into amino acids. So this is kind of like our characters. Whereas english and spanish have similar alphabets. Nucleotides and amino acids are not similar at all. It's much more diverse languages. And so we can kind of think of nucleotides and amino acids as our alphabets. Okay and so that's trans translation translation is the process of converting this alphabet. These nucleotides into this amino acid alphabet. And so in terms of alphabets, how are they similar? So we know that there's four nucleotides, right? We have A. T. C. And G. But we have 20 amino acids. So there's a lot more amino acids than there are nucleotides. And so that means that translation is not 1 to 1. It's not that nucleotide a. Um and codes for amino acid one. And that G codes for amino acid to. Right that's not how this works because because there's not four amino acids if there were four nucleotides and four amino acids we would think okay well one nucleotide equals one amino acid. That's not the case. And so because it's not the case, we have to decode exactly how to translate these four nucleotides into amino acids And how we do that. How we decode that process is through a code on. So what is a code in a code in is a group of three nucleotides that represents one single amino acid. So it takes three nucleotides to create a code on and three nucleotides and code for an amino acid. So we're starting to get our rules here how the alphabet of D. N. A. Can be translated into the alphabet of amino acids. And in order to do that we have to take at least three letters of nucleotides to code for one amino acid. So knowing that the next thing that we need to do is say, okay well we're looking to translate this paragraph for instance in english spanish. Well we know where the start of the paragraph is, right? So usually there's an indent. If we're looking at it on a piece of paper, we can easily tell where the start of a paragraph is. But for D. N. A. That's not necessarily the easiest thing to identify, right. Because unlike written word, where we can we have the structure of a paragraph, we can see where it starts. D. N. A. Is just a combination of nucleotides. Right? It's just like one long line of these random four nucleotides repeated in different combinations again and again and again for thousands and thousands and thousands of letters. So where do we start? So in order to identify where we start, where that start of that paragraph is we look for a start code on which in this case is A U. G. So here's these three nucleotides that encode for the start code on. So we have three nucleotides, A U. G. And it encodes for one amino acid. So what's that amino acid? It's going to be um a thinning. And this is actually going to be a special method meaning. So this is the amino acid names Metheny and usually it's a special type of Metheny that's used to only start the paragraph for instance start the translation of the gene there and it's always the starting amino acid. So we want to know where to start the paragraph. We look for A U. G. We also need to know where to end the paragraph. And so that's when we look for stock code on. Now. There's more than one stock code on. U A a U A G and U G. A. But these do not actually code for amino acids. So this is kind of unusual because the rest of the three different nucleotide combinations and code for amino acid. But stop code ons don't they're the only exception. And what they do is they just say stop here. It's kind of like a period at the end of the paragraph. So that they know that this is where you need to press enter on your word doc. And start a new paragraph. So we have a start code on that says here starts the paragraph. We have a stock code on which is the period you press enter. And then you can start something new. Um So that is code on. That's how we is kind of our dictionary of knowing you know what three nucleotide combinations equal a single amino acid. So the next thing we need to know is that the genetic code is redundant. Um You may also see this as degenerate. So what does this mean? Well the scientific definition means that multiple combinations of nucleotide and code for a single amino acid. But in terms of just going back to our example that we've been talking about translating english to spanish. For instance we know that english has multiple synonyms, right? It has words that are different. They're spelled differently but they mean the same thing. And the genetic code is also like that where you can have multiple combinations of nucleotides. That mean the same thing, meaning that they all three, even though the nucleotides are different, can encode for the same amino acid. So they're actually 64 total nucleotide combinations. How I know that is that we have three spots right? For code owns there's three nucleotides and there's four possibilities for each spot. Each one of these can be a T. C. Or G. Each one of these can be a T. C. Or G. And each one of these can be a G. C. Or G. And so if we multiply four x 4 x four we get 64 different combinations that can occur for each for code ons right there, 64 nucleotide combinations with three nucleotides. But we only have 20 amino acids. So it's clear that it's not every single one of these combinations. Each one of these 64 unique combinations can encode for the same amino acid. Um Just like synonyms have looked different, they're spelled differently right? But they have the same meaning the exact same way. And this is actually really important in terms of evolution. I'm only gonna mention this here because we're not talking about evolution right now. But you can imagine um having this redundancy having synonyms in the genetic code means that if you have a mutation right? If you spell a word wrong um it lessens the effect because you still have um all of these synonyms that could be similar. Um and sort of lessen the effect of a single mutation. So but I'm only gonna mention that here briefly because we're not talking about evolution, we're talking about understanding how to translate things. So the next thing we need to do and that this is a little bit different than our traditional example and that is reading frames and there are three reading frames each beginning with a nucleotide within the first coat on. Okay. So remember we talked about where to start the paragraph. Right? We looked for the starting coat on. And when we're writing a paragraph in english translating that to spanish it's clear we can clearly see the start of the paragraph but we can't necessarily clearly see that in DNA. That's why we need to start coat on. But in addition to that there could actually be multiple start Cardin's right, there's not that many nucleotides and they have to be arranged in different combinations. So you can have multiple start Cardin's in a single transcript. Right? That we're using to translate D. N. A. So how do we know which one's right, which one is the correct start code in where do we actually need to start? And we determine that through the reading frame. And so what this is is we have all these C. Let's pretend that all these lines right here represent DNA nucleotide. So um so each three of these represents a nucleotide. Now. We could have a U. G. Here, right. And different nucleotides here. But we also could have another au G. Here. So which one of these is correct? So the reading frame determines that the reading frame if the reading frame is here. Right? So this one this one and this one this is code on one. Then this reading frame here will say this is the starting frame or the starting code on. This is where we're gonna start but we can actually have other reading frames here too. Right. If we started at this, you if we said that the issue was the first nucleotide then we would have 123 and that would be reading frame to reading frame one and reading frame to. Or we can start here reading frame three. Now if we kept going reading frame one reading frame too. So now we have to start code on this one will start it if we choose reading frame one and this one will start it if we choose reading frame to now in um in the cell the cell knows which one is the correct reading frame. But but we don't write we we aren't that smart yet. We don't necessarily know how to decode the genome that well. And so if we are just looking at A D. N. A sequence. For instance, if your professor gives you A D. N. A sequence on an exam or on a quiz and tells you to change the D. N. A. To uh protein to translate it. You need, the first thing you need to figure out is all the different reading frames that are possible. And so in this case it would be hard for us to determine. Right? Because I don't know I don't have any information whether reading frame one is correct or reading frame too. But I could use some other information about the sequence to determine which one is correct. For instance if I have if reading frame one starts off with a start coat on and then the next three amino acids? Where a stop code on. That's probably not the correct one. Right? Because we don't want to start, why would we start a paragraph and have no words in it? Right. That makes absolutely no sense. So we wouldn't want to do it if a stock code on is directly after. Whereas if reading frame to if we started there but then we had 30 sequences, 30 more nuclear ties. It created a nice little 10 amino acid protein. Then then how to stop code on that makes much more sense. And so we have to use other information about the sequence in order to be able to determine which reading frame is correct. But you need to make sure that if you're given a sequence to translate, you check out every single reading frame. Is that these nucleotides with reading frame one, these nucleotides with reading frame two or these nucleotides with reading frame three, That's the correct way to translate that sequence. That's a big way that professors try to trick you up and get you to miss the translation question because they just assume that you'll start at the very first nucleotide. They give you and translate it that way but make sure that you're examining all the different possibilities and which ones most likely with the correct reading frame. And so um reading frames are super important. Right? Because that can be different between having a paragraph with one word or an entire paragraph with like multiple sentences. Right? And so reading frames are crucial and actually only one reading frame is correct per gene. So if we have a transcript, all the machinery has to find the correct reading frame. So that it's right now. There are mutations called frame shift mutations. And we'll talk about more of those later on in symbology. But frame shift mutations are mutations that disrupt the correct reading frame. So for instance, if you delete a nuclear taider, you get rid of a nuclear tide, that's going to shift the correct reading frame. If you add a nucleotide, that's also going to shift the correct reading frame and it can be completely just destroy the protein we're supposed to create. Especially if you if you disrupt the reading frame in a stark coat on or in a stock coat on because either it won't get started or it won't be stopped. And that can just result in ridiculous proteins that either never created or way too long or just encode for all sorts of crazy things that they wouldn't normally encode for. So friendship mutations can actually be very, very damaging. Now we talked about translation. Just want to mention something real fast now in our world and human language, there's a ton of different languages, right? I mean there's just so many hundreds and hundreds of languages that exist, probably even thousands really of languages that exist across the world. But when it comes to the DNA to protein language it's pretty universal. Um It exists in pretty much every organism on earth the exact same way. So the same combination of nucleotides encodes for the same amino acid no matter who you are or what organism you come from. But there are a couple of very very very small exceptions. An example of this is mitochondria which mitochondria actually has its own D. N. A. It has a small amount of its own D. N. A. Uses A G. A. As a stock code on and that's different from every other living thing on earth bacteria, plants, us, everything else. Mitochondria used to stop code on mitochondria also use U. G. A. Which is gonna be a stop code on for us and said but in mitochondria it imposed for tryptophan. So again this is just a small example. Like I said the code is nearly universal but there are a couple of in this case mitochondria but there's a couple of other examples to where the code on isn't exactly right or the is not exactly universal but the rest of everything the mitochondria uses is the exact same as everybody else. It's just here's a couple examples of how they're different. So let's look at an RNA sequence, let me disappear. So you can see it. So we start with um RNA here remember transcription goes from D. N. A. To R. N. A. To protein and translation starts with R. N. A. I've been using the term DNA a lot because RNA is just a copy of D. N. A. It just uses slightly different nucleotides. But translation is really the RNA to protein. So here we have our nucleotides and here they are here's their basis G C U A C G etcetera etcetera etcetera. Now this here is reading frame one. This is going to be this code on and that means G C U N codes for the amino acid Alani um A C. G. And codes for three and N G A G includes for glutamate. See you you enclose for losing and so on and so forth. Until we reach a stop code on which doesn't encode for anything. But just sort of lets the lessons I'll know that it's over. We're ready to move to the next paragraph. Now if it's if it changed a reading frame if there was potentially a frame shift mutation or something or the reading frame is off we could read it like this. Right see you a C G G A G C. That would be one that would be a second type of reading frame. Right. If we do reading frame one here this would be reading frame too. But we also have a third reading frame which would be you A C. Reading frame three G G A. Reading frame three G. See you reading frame three and so on and so forth. So make sure before you try to do any kind of translation on any kind of quiz or exam you are confident of where the reading frame begin because I guarantee you use a professor is probably going to try to trip you up on that way. So first thing is always to figure out what the reading frame is and then you can actually use a dictionary, an example of a dictionary. But essentially it's just which nucleotides and code for which amino acid to actually translate from RNA to protein. So with that let's move on.

tRNA Processing

Okay, so now let's talk about T RNA processing. So T R N A. R. The R N. A molecules responsible for matching amino assets to the proper code on. So before we talked about, you know what's the vocab? How do we understand? Where do we know where to start? A paragraph and into paragraph in terms of translating? But T R N A S are actually the guys doing the translation. So if we have a paragraph we wanted it translated from english to spanish we would need to go someone go to someone who could read both english and spanish and translate it. T N. A. Are those people? So what does the T. R. N. A look like? So T RNA has, it's an RNA molecule like I said but it 75 to 80 nucleotides in length and the RNA comes together, it forms a double helix and that double helix again conforms a little bit differently to look like an L. So here's an example of that. You can see the L. That was kind of upside down this way but there we go. Sometimes people say, it also looks like if they draw in this formation, it looks like a clover leaf, you can see the three leaves here and the colors this actually represent the same thing. But this is what a T RNA looks like. Now in terms of translation, there's a lot of different structures. Each one of these colors represent the different structure but but you only need to know about a couple of them, You need to know about the anti coding regions of the region that can read english for instance or in terms of translation RNA. And the amino acid binding regions. So that's going to be the one that can read spanish or in this case the amino assets. And so um let's talk about each one of these individually. The anti code in region is going to be made of nucleotides that are complementary to the code on. So if the code on is a U. G. Then the T. RNA is going to contain RNA that's complementary. So it's going to be T. A. C. So the anti code on is just a region of these three nucleotides complementary to the code on it binds to. And so and then that would be the english region. The spanish region is the amino acid binding region and what it is, it's the three prime end of the T. R. N. A. It's a single stranded area. And this attaches to the amino acid. So if we're looking here, what we're going to see is that this region here is going to be the amino acid binding region. So an amino acid is going to come on and bind here. And the anti code in region code on region is going to be here in gray and this region is going to bind to the RNA recognize the code on. And it'll have an amino acid attached onto onto it. So that's what it looks like. But Well first let me tell you that when the RNA is made right, when we transcribe DNA into RNA and there's DNA that codes for T. R. N. A. And when they're transcribed it's not automatically that tiara is just perfect. It's rare to go as soon as it gets transcribed Tr is the key to be processed. But the processing that they undergo is different than that of M. RNA. So we know that M. RNA is whenever they're transcribed they have to have a three prime or they have to have a five prime kappa three prime poly a tail. They need to be spliced T. RNA, I don't need any of that. They have to undergo a variety of different processing steps um which are not the same examples of this include edition of certain chemical groups. Um replacements of Euro sales with the CC. A. Sequence and there's a few other different types of modifications that aren't, you know super important for you to need to know some of them do have to undergo splicing. Some of them do contain N tron but not all of them and there are a total around 50 nucleotide modifications um found in T. RNA. So when the tR transcribed they have to go under undergo some type of modification process which can be more extensive than that of M. RNA with 50 different types and then whenever they're all processed they're ready to go now in the example we talked about when we wanted to translate something from english to spanish. What you would need is you need a translator, you need one person to sit down and actually translate english to spanish. But Tr don't actually work like that, they're really not as smart as a human translator would be and instead only trn A can only attach to one um or a couple of different amino acids and so it's kind of like T RNA is only understand really one word, one coat on and they can attach to a couple of different amino acids. Remember because there are those synonyms, so a few different code ins can have the same amino acid. So it's not exactly a 1 to 1 ratio but T. R. And s don't really, they can't translate a whole paragraph or a whole sequence. They can only translate one, maybe two code ons. And so um so keep in mind it's not just one translator. You actually kind of need a fleet of T R N A. S in order to be able to translate an entire DNA sequence. However like I said, it's not once one, there's not 20 tr N A S for 20 amino acids and that's because some T R N A. S combine to multiple amino acids. But it's also because of this process called the wobble hypothesis and this is something that you probably saw a bio 101 something professors like to quiz you about and essentially what it is is you have three nucleotides. This one is really fixed. It has to be whatever it is, this one is fixed. It has to be whatever it is. But this position can wobble. So what do we mean by wobble? We mean that it doesn't have to always be fixed. It can be a couple of different nucleotides and it won't mess up anything in terms of translation. So the first two nucleotides are essential to getting the correct code on magic to the correct amino acid. But the third nucleotide doesn't have to be as structured, it doesn't have to be as fixed. It could be a couple different nucleotides but still the T. RNA is going to recognize it and provide the correct amino acid, still going to translate it the same. So the correct type of the correct definition for this is that the mismatch between the code on and anti code on at the third position. So we have this one has to be correct. This one has to be correct for the T. RNA to match it with the correct amino acid but this one can be a little bit more flexible and the T RNA is still gonna recognize it. The code on and still provide the correct amino acid. And um if you actually look if you sort of google like an example of a nucleotide and amino acid code, you'll understand that actually the third position is really the least important and making sure that the translation actually occurs and that's kind of different than if you are going to translate english and spanish. You really need to know the full spelling of the word. But in terms of translation, that's not actually the case. The first two nucleotides are super important where the third is a little more flexible now like I said before, it's not just one T RNA that is responsible for translating the entire RNA sequence into amino acid that they're kind of like a fleet of Tr nasr necessary. And each T RNA focuses on one or two words to translate or one or two code on in order to translate into and the appropriate. You know I said. And so how T RNA work is they they attached to amino acids, They attached to the RNA the code ons. And that allows for the structure called the ribosomes which we're going to talk about next um to uh bring together the M. R. N. A. And the amino acid and actually process the translation. So how do we actually get how do we teach the tr N. A. S? The difference between english and spanish. So when the Tr nasR created we go back to their structure here right they have a nucleotide sequence. So the T nasR kind of born already understand like already knowing how to bind to code ons right? That that nucleotide sequences in their structure. But they have to be taught the amino acid that they're going to attach to because something has to attach that to them. So they're kind of born or created already knowing one language that code on language. But they have to be they have to be taught which amino acid to bind to. And so that teacher is actually amino acid T. RNA synthetic and it's a protein. And what it does is it takes the T. R. N. A. And it attaches the amino acid um to the correct T. R. N. A. And through forming this bond. So it looks over all the T. RNA. It figures out which one has the code on for its amino acid and it attaches it onto that T. RNA. It teaches it that that how to translate the code in that it's born with into the amino acid. So again attaches onto the three pro time in which is where that amino acid binds. Um and then whenever the amino acid is added onto it we say that that T. R. N. A. Is active or it's charged. So if it's a T. RNA without an amino acid before it's taught how to translate then it's inactive. But as soon as it's taught to translate it becomes active or charged and there is one amino assault er and a synthetic for each amino amino acid. So there's 20 total. So if we start Here it's kind of hard to keep track of this. So we have 20 synthesis, Right? one for each amino acid and each one of these ads onto a specific or to a TR N. A. But there's not not 20 not 20 TR N. A. Right? Because T. R. N. A. S can be a little bit redundant. They can bind to a couple of different amino acid tr uh they can buy to a different a couple of different amino acids. They can buy into a couple of different code ons depending on the wobble hypothesis. And so um yeah so there's so important to keep in mind 20 total synthesis one for each different type of amino acid. But they combined to a couple of different types of DNA is because a couple of different T. RNA can bind to different code ons but and code for the same amino acid. So how do we make sure that this amino assault T. RNA synthetic? Right? There's one for each amino acid. We want to make sure that it's adding the amino acid onto the correct T. RNA because we do not want to mess that up, right? Because the Tr nasr born with that coat on, they know that they have that code put on that sequence. But whatever is added on to them, that's what they're going to translate. So if they get the wrong amino acid that's going to entirely mess up the entire sequence of the protein and we don't want that. So in order to make sure that that's correct. There's a couple of different processes that allow for the matching of the correct amino acid to the correct two RNA. And so one of the ways that this happens is through affinity, meaning that the amino acid is going to want to bind to the active side of the T. RNA synthesis, that is correct. Right. So the amino acid only is going to have the highest affinity, meaning that it's going to be drawn to or be able to bind to the strongest way in to the synthetics. That's correct for it. And so we don't want to mess that up. So one of the ways is that the amino acid wants to bind to the correct synthetics. But the second way is actually through a proof reading process where the synthetic taste actually like can check whether the amino acid that's bound is correct. And so if A T. RNA tries to fit within a specific pocket, so the amino acid comes in right? It binds to the T. R. N. A. And it binds in a specific and there's a specific region for that for this pocket. And so only certain amino acids can bind um in this pocket. And if they are if they bind in the pocket, right? So if they bind in the pocket a little bit different than you would think then they are not correct. And if they do not bind in the pocket disappear. So you can see this then they are correct. So, proof reading T RNA has this pocket, the amino acid can can either bind to this pocket or not. The correct amino acids are excluded, meaning that they do not bind in this pocket and then they can fully bind to the T. R. N. A. So I think that's everything you would ever need to know about T. RNA is. They're super important that the people who translate RNA to protein. They are not necessarily smart as a single translator who would be translating something from english to spanish. But the fleet of T. RNA is one for one or multiple amino acids can come together and actually make sure that the translation process is specific that and that the correct amino acids are pairing with the correct code ons. So with that let's move on.

rRNA Processing

Okay so we've talked about code in so we've talked about T. R. N. A. Now we're gonna talk about our RNA. And the river zone. So in our example of translating english to spanish. We have gone through code ons how that fits into this example. How we need to know the dictionary, we need to know the vocab, we need to know the alphabet, we need to know the reading frame to figure out what order things are red in the start and stock code in to figure out where the um sort of the paragraph or the gene starts and stops. Um In terms of T. RNA we need people who can actually translate translators right and tr and act like that and we know that there's a specificity to it but now we need to focus on ribosomes. And so in this example of english to spanish translation, ribosomes would kind of be like the pencil. So if you wanted to um have somebody translate a paragraph of english and write down the paragraph of spanish you need a tool to be able to do that. It could be a pencil, it could be a word doc whatever tool you want to use right as always the tool to actually combine everything together. The knowledge from the T. R. N. A. S. This code on code and actually turn it into or translated into protein. So ribosomes are made up of ribosomes RNA and ribosomes from the majority of the ribosomes. So our RNA is ribose in RNA is that are responsible for translating RNA to protein. Remember they kind of act like the pencil to do this. Um Now it says the majority of the rivers um because the river is um is made up of both our RNA and proteins but our our nasr the real important part of this. And so in pro carry optics sales, there's three different types 16 S, 23 S. And five S. You really probably don't need to know the differences between these, but there are three different RNA S. And in pro carry oats in order to create the R. RNA, there's actually just one transcript that encodes for all three of these and the processing separates them and then forms them into the pro carry arctic river zone. And you carry out there's an extra four R. R. N. A. S. Hear their names. Um and in eukaryotes, three of them, the five S. The 5.8 S and the 28 S. Are also encoded in the same transcript. And then once they're transcribed processing allows them to be separated and then put into the river zone. So um because if you're going to encode multiple genes on the same transcript, obviously there needs to be processing. So our RNA must be processed and cleave meaning that these are separated right into the individual R R N. A. S. Before they can form the river zone. So what are examples of processing things that can happen to RNA now when we talk about processing RNA, we're typically thinking or thinking about the processing of M. RNA. The addition of the five prime cap, the poly a tail splices. But our our NHS again like T. R. N. A. S are processed differently than M. RNA. And so oftentimes what this happened, what happens to our RNA is for processing is individual nucleotides are slightly altered chemically. So an example of this would be adding a methyl group onto an individual nucleotide onto a Euro sale for instance or side of scene whichever it wants to. Um And in addition to these nucleotide modifications, there can also be confirmation of changes in the structure to remember. Our RNA is have the ability to fold into these complex structure and that gives them the ability to act almost like enzymes. And in the ribosomes they do act like sometimes they exert some type of function to allow for translation. And so our R. And S. Have to be folded in a certain way to allow that. And changing that structure of the RNA. And changing the confirmation can change its function and help process it into its final rivers own form. And our our nasr actually there's a ton of them right because ribosomes are necessary for all types of translation and we constantly need to be producing more proteins. So actually the total amount of RNA in the cell. If you think about how much is in there. T. R. N. A. S. M. R. N. A. S. And things that are making proteins. But ribosomes RNA is makeup nearly 80% of that total. So the other 20% is made up of the stuff that creates proteins and T. R. N. A. S. And other small RNA as well. But nearly 80% of all the RNA in the cell comes from ribosomes RNA. So it's obviously a lot and all of its used to create ribosomes. So there's a ton of ribosomes in the cell. So here's an example of the five S. RNA. And you can see that I mean it's RNA but it forms this complex structure here and that structure then is incorporated with other R. RNA other proteins. And that creates the rift zone. So now that we talked about the RNA, let's actually talk about the rhizome itself. And the riot zone consists of two subunits a small and a large. And this the names of the small and large just depends on how many are RNA are included. So in procuring votes, the small sub unit has the 16 S. And the large subunit has the 23 5 S. And in eukaryotes the small subunit has the 18 S. With the large containing all three of these. And so um yeah so those are just good things to memorize. You know I just read that off the thing but there's nothing really else to say about that other than it's good to know which are RNA s are responsible for each sub unit for small and large for both prokaryotes and eukaryotes. So small nuclear RNA is this is a different type of RNA. And um what it does is it helps it can bind to the pre R. RNA. So what is the pre R. R. N. A. That's going to be the unprocessed RNA transcript? So we have D. N. A. Here, right? And it's going to undergo transcription to create the pre pre R. R. N. A. And then it will undergo processing to become the final R. R. N. A. Transcript. And so how does this happen? Well the snow are in a bind to the pre R. N. A. Right here. And then when the small RNA, the snow RNA. Is here buying to the pre RNA. It allows for proteins to come in. And whenever we have this complex of the pre R. R. N. A. The and the snow RNA. And the protein we call those snow. Our Nps. So we get a little bit confused on what we're talking about. But you notice here that all the RNA RNA is in them if it says R. And P. S. There's some type of protein incorporated into that. And so these um snow R. And P. S. Help to position the R. R. N. A. S. Which are being processed right? Um for processing. So we have to connect. So in order for the RNA to be processed, we have to connect them with these different types of RNA. Is these different proteins so that they can be processed and the snow our mps really help with that process. And so the summary of this though, the really important crucial part that you need to know is that the ribosomes is formed by these processed RNA. And proteins. And the R R. N. A. S are the most important. I. M. P. O. R. T. A. And T. Most important because they're the ones with the functions. They're the ones that are sort of helping this translation process along. The proteins don't really do much other than just provide a little bit of support and structure to the ribosomes. So here we have an example of what arriba zone looks like. Um the we have the large subunit here and the small subunit here. And what happens is that the R. N. A. The M RNA is fed through this way. Right. And T R N. A. S. Can come in to the area and that allows for the cattle of the connection of the code on in the RNA and the anti code on and the T. R. N. A. And then that connects the amino acid and that is how translation occurs. Um Yeah, so we'll go over this process this one here much more. But just that's just a very brief overview. So that's the ribosomes and our R. And S. So with that let's move on

Which of the following is not true about the codon code?

• A. One sequence (AUG) initiates translation
• B. The number of codons is more than the number of amino acids
• C. Out of three possibilities there is only one correct start site (frame) for each gene
• D. Anticodons are encoded in the DNA of the gene

Aminoacyl tRNA synthetase is an ezyme that is responsible for doing what?

• A. Forming the tRNA into its cloverleaf structure
• B. . Binding the tRNA anticodon and mRNA codon together
• C. Attaching the amino acid onto the tRNA
• D. Attaching the amino acid onto the growing polypeptide chain

Which of the following rRNAs make up the small subunit of the eukaryotic ribosome?

• A. 18S
• B. 5S
• C. 16S
• D. 28S