hi everybody welcome back and today we're going to be doing the second part of our two-part video on protein synthesis and we're going to be looking at translation now in our previous video we discussed the idea around transcription and essentially transcription is when we take a dna molecule and we want to create a particular protein but we don't use the entire dna strand instead we unzip just a section of the dna that we want and then we copy or transcribe the piece that's going to code for the protein that we want and that then results in our rna the particular piece of rna that we make is an mrna or a messenger rna and we call it that because it simply carries the message required to create the protein that we are looking for but now we need to look at how do i take that message which is a coded message and make it readable so that i can actually turn it into a substance and this substance being a polypeptide chain where we can form a protein from that and that process is what we call translation and translation therefore means that we're going to read that mrna and we are going to translate it into amino acids and then into a polypeptide chain of those amino acids now before we move on to the specifics of translation i just want to highlight where exactly these two processes are actually occurring transcription is occurring inside of the nucleus and once we have made that mrna molecule that's carrying the coded message we need to go out of the nucleus through the nuclear pole and we're going to enter the cytoplasm in the cytoplasm we find the ribosomes and the ribosomes are where protein synthesis occurs they're like little protein factories so just to ensure that we know exactly where we're going with this let's just look quickly back at transcription so transcription was when we took a region of our dna molecule we unwound it and as you can see here we're forming a new strand of mrna messenger rna and mrna is written in three letter sets which we call codons and it's important to remember that those codons are formed based off of the template that the dna is providing and that template then tells us which complementary base pairs we need so that we don't forget adenine joins to uracil now whereas cytosine and guanine still are the same complementary base pairs as they were before you should never see a thymine or the letter t in the mrna strand that you have written down otherwise you have then made a mistake transferring your complementary base pairs the mrna now leaves through the nuclear pore and it's going to go into our cytoplasm where it's now going to go through the process of translation now in order to facilitate protein synthesis we need three things and the first thing we already have is the mrna strand that is the strand that's going to carry the genetic code that we want to translate into proteins the second thing that we need is a trna molecule which i'm going to explain exactly what that is now but essentially it's a transfer rna its job is to carry around packages of amino acids to their corresponding mrna strands last but very important is a ribosome and ribosomes are those organelles that we find either floating out in the cytoplasm of a cell or they can be attached to the endoplasmic reticulum right near the nucleus itself which is perfect for translation because then the mrna doesn't have to travel very far distances and remember ribosomes are our protein factories so that's where we're going to then actually make our protein so let's look at trna and its structure so a trna molecule gets its name because it is a transfer uh rna but also it has some similarity to the letter t not really quite other people think that it also looks like a clover shape and the most important parts of a trna molecule to us in terms of translation is the amino acid which is carried at the back of the trna and that amino acid can actually move away and what that means is is that essentially trna is like a delivery man it picks up an amino acid and it can deliver it to the ribosome but how does it know which amino acid to pick up it knows based off of the anticodon which we find at the bottom of the trna molecule and the anticodon is complementary to the codon we find on the mrna molecule and so as the ribosome reads the mrna molecule a trna molecule with its anticodon will match it now that we're aware of all the components needed for protein synthesis and translation let's look at step one so we have our mrna molecule here and in the background this greeny colored round structure is our ribosome and so the mrna enters into the ribosome and the ribosome is going to read the mrna codons which are those three letters in other words we're going to read the code three letters at a time as the ribosome reads the codons it is going to then want to pair those codons with their complementary bases found on the trna and their anticodons and in this picture what basically is happening is if you can look at our ribosome there's actually three stages of translation happening here we have a trna molecule that is leaving the ribosome we have a trna molecule that is entering the ribosome and then we have a trna molecule that is already in the ribosome and is currently being red and so what the ribosome will do is it will take these codons that are found on the mrna in this case it's got u g g and it's going to partner it with its complementary anticodon found on a trna molecule and those trna molecules are floating around in the cytoplasm and in this case the complementary piece is acc so now that we've joined the anticodon with the codon we need to start forming a polypeptide chain of amino acids and that's the next step we're going to look at attached at the back of every trna molecule is an amino acid and as i mentioned earlier these amino acids can come and go in other words they're there to be delivered and so you'll notice that this incoming trna molecule has a amino acid attached to the back whereas this outgoing one doesn't have any and that's because it has already left behind its amino acid now there are 20 amino acids in total and every single living organism on the planet has the same 20 amino acids which essentially means that there's further proof that evolution has taken place where we all have the same common ancestor because all of our code is written in the same four letters and all of those four letters code for the same 20 amino acids what makes us unique however is the order in which we put those amino acids together and then eventually the long polypeptide chains that are formed what makes those proteins unique to each organism that we find them in so essentially what we need to happen now is we want those amino acids to be delivered and then attached to one another our trna has brung our amino acid it's delivered it and it's joined it with other amino acids and it's going to form a peptide bond between each of those amino acids and as we can see in the diagram here we have one amino acid which is joined to a second and that is done through this peptide bond that is forming between them now once it's delivered its amino acid it is going to move away from the ribosome so that the next incoming trna can take its place and it can bond with its complementary base pair now as that trna moves away and it's replaced by a new trna the old trna that has now no amino acid attached to the back of it like this example here in our diagram there used to be amino acid here it goes off into the cytoplasm to collect another amino acid keeping in mind that that amino acid must match the anticodon on the trna now this is just a final look at both of the processes happening together in the same image so you can just get a good idea of how you would have to explain this or label it in diagrams and pictures and exams or tests and so transcription is happening in the nucleus it's where we copy the code it's where we make our mrna that mrna moves through the nuclear pore into the cytoplasm where it is read by the ribosome and as the ribosome reads those three letters at a time those codons the trna comes along with its anticodons it finds its complementary bases on the codon and it delivers an amino acid we connect enough of those amino acids together with peptide bonds and we finally form a polypeptide chain keep in mind that a polypeptide chain is not a protein yet but if you put enough of these polypeptides together you will form the resultant protein that you are looking for and we can use that protein for a number of things we could make a new cell membrane we could be producing an enzyme we could even be producing a muscle fiber all of these proteins are coded for by amino acids so ending off this lesson let's look at the terminology recap we learned about translation which is effectively where we take our piece of mrna and we translate it into a polypeptide chain that will have the ability to then become a protein we learned about trna molecules which are transfer rna molecules that act like delivery molecules in picking up an amino acid and joining the amino acids together to form a polypeptide chain and found on those trna molecules are anticodons and anticodons are sets of three letters or nucleotides that are complementary to the codons which we find on the mrna now we also learned about amino acids and amino acids are the building blocks of proteins they are the monomers all of this protein synthesis happens inside the ribosome the ribosome being the site of protein synthesis the protein factory if you will polypeptides refers to many amino acids and when i say many i mean more than 50 that have joined together to make a long chain and holding that polypeptide chain together is what we call a peptide or or what we correctly referred to as is a peptide bond which holds all of those amino acids together it's important to be able to explain both transcription and translation very specifically using your terminology and i suggest that you use your exam guidelines to help you do this so that you use the correct terminology and you get the maximum amount of marks i hope you've enjoyed the video and if you like it please give it a thumbs up and subscribe and i will see you all again bye