So in this video, we're going to continue to talk about ways that cells can regulate their biochemical reactions by introducing post translational modifications and so recall from our previous lesson videos. That translation is the cellular process of building proteins by using the encoded messages of M R N A. And so the prefix post actually means after and so like a postgame interview is an interview after the game. Post translational modifications are just protein co Vaillant alterations that specifically control protein activity and take place after translation. And so post translational modifications are sometimes abbreviated as just p. T. M's. And it turns out that there are many different types of post translational modifications several hundreds, for that matter. And so we're not going to be able to cover all of the different types of post translational modifications and our course. But there are some mawr common types of post translational modifications that we expect your professors might want you guys to know about, and these include methylation, assimilation, ubiquity, nation and phosphor relation, and so down below. In our example, we're showing you guys just a small handful of some post translational modifications, and so notice towards the top of our image. Over here, what we have is this pink squiggly line which represents our M r n a molecule. And this pig arrow going downwards right here represents the process of translation. And so translation is going to build our protein molecule, which is right here using the encoded messages of Marna. Just like what we mentioned up above. And so again, any co Vaillant modification that occurs to this protein after the process of translation is referred to as a post translational modification. And again, there are many different types of post translational modification. So these are definitely not all of them here. And we're only showing you a small handful, nine of them to be specific. And so the first post translational modification that we're showing you guys is hydroxy elation and hydraulics. Elation is just the process of taking our protein and cove intently, adding a hydroxyl group to it. So hydroxy elation and the hydroxyl group. Now, if we take our protein and instead of adding a hydroxyl group, we add a methyl group like this one, a C H three that is referred to as the process of methylation which is pretty straightforward, just adding a simple metal group. Now, if we take our protein and we add a lipid to it, it's referred to as lipid ation, and lipids tend to have these large hydrocarbons like this one right here. Now, if we take our protein and cove intently ad and a Seattle group like this functional group right here, this is referred to as a seat elation Now moving on to our next post translational modification. What we have are die sulfide bonds, which we have talked about before, and our previous lesson videos. And so we know that die sulfide bonds will form between the are groups of two Sistine amino acid residues linking potentially linking to separate Polly peptide chains. Now the next post translational modification that we have here is ubiquity nation and ubiquity nation. We will talk about mawr as we move forward in our course, but really it's just this process of taking a protein and covertly adding a small protein to it, uh called ubiquity in. Now, the next post translational modification is sulfa nation, which is adding a sulfate group to the protein and then we have, like oscillation, which is adding a carbohydrate to our protein. And then last but not least, what we have appear is Foss for elation, phosphor relation and fossil relation. We will also talk more about later in our course, and it's simply the process of adding a phosphate group to our protein. And so this year concludes our introduction to post translational modifications and Aziz, we move forward. In our course, we're going to continue to talk about very select types of post translational modification, so I'll see you guys in our next video.
Post Translational Modification
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so another type of post translational modification that your professors might expect you guys to know about that we didn't cover in our last lesson video is Prodi elliptic cleavage, and so Prodi. Elliptic cleavage is just the process of breaking down peptide bonds between the amino acid residues of proteins. And so, of course, this process of Prodi Olynyk cleavage is going to require Proteus is, or peptide aces, which we've already covered in our previous lesson video. So we know that pep today's is, or Proteus is are just enzymes that cleave peptide bonds at very between very specific amino acid residues. And so notice down below in our image here, on the left hand side, what we have is our protein immediately after translation, and so some proteins immediately after translation are actually inactive, and so they do not work and cannot perform their job when they are in this inactive form. And so, in order to activate the protein, some proteins need to go through the process of Prodi Olynyk cleavage. And so this arrow right here represents the process of protea Olynyk cleavage, which is going to require a Proteus or pep today's. That's essentially going to act like molecular scissors and cut our protein. And essentially, what that's going to do is it's going to activate our protein. And so here. What we have is the active form of our protein, and sometimes that can also generate inactive, uh, forms of our protein or cleave off inactive forms of our protein. Now here in this image, since I put together this image here, it looks like I took a hacksaw and just cut straight down the middle of our protein right here. Thio cut it in half, but essentially, that explains why I'm not a Proteas. But we do can get the point here that Proteus is are going to cleave some specific peptide bonds in order to activate our protein and potentially cleave off other inactive forms from the protein. And so we'll be able to talk even Maura, about Prodi Olynyk cleavage later in our course, when we're talking about Zim Mogens. But for now, this concludes our introduction to Prodi athletic cleavage, and we'll be able to get some practice with the concepts that we've learned as we move forward in our course. So I'll see you guys in our next video
Which of the following would not be a reversible post-translational modification?
An enzyme’s active site has high affinity for a polar charged substrate. How will methylation of the active site affect the reaction rate of the enzyme?
Affinity for the charged substrate will increase thereby increasing reaction rate.
Affinity will remain unchanged, and therefore will be independent of the modification.
Affinity for the substrate will decrease, lowing the reaction rate.
Histones are proteins that regulate gene expression by binding to DNA and controlling which regions are exposed to be expressed. Histones bind to DNA at a neutral pH via their positively charged lysine residues, but acetylation of histones leads to the dissociation of the DNA-Histone complex. Covalent modification of lysine’s ammonium group by acetylation results in an overall _______________ charge of the histone binding region.