4. Biomolecules
Monomers & Polymers
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In this video, we're going to talk about building and breaking down polymers. And so if a cell wants to build a polymer, then it needs to perform a dehydration synthesis reaction. And so as its name implies with the synthesis part here, dehydration synthesis reactions are going to form covalent bonds to link individual separate monomers together and begin to build a polymer. And so you can see that the synthesis here is all about forming and building a polymer. Now, on the other hand, if a cell wants to break down a polymer into its small individual pieces, then it needs to perform a hydrolysis reaction. And so dehydration synthesis and hydrolysis reactions are opposite of one another. And so hydrolysis has the root lysis in it which is all about cleaving and breaking things down. And so hydrolysis is going to cleave covalent bonds between the monomers and release the monomers as separate pieces by breaking down the polymer. And so once again dehydration synthesis is all about building a polymer, whereas hydrolysis is all about cleaving or breaking down the polymer. So let's take a look at our image down below to get a better understanding of the formation and breakdown of polymers. Now what's important to note is that on the left hand side of our image, we have 2 separate monomers, one over here and one over here, And on the right hand side of our image, notice that those monomers are now joined together covalently, and so it's starting to build a polymer over here on the right hand side. And so of course if we want to join together 2 separate monomers and begin to build a polymer, we're going to need a dehydration synthesis reaction. And so, in the dehydration synthesis reaction, the hydroxyl group, the Oh group of 1 monomer is going to interact with a hydrogen on another monomer, and so Oh and H are going to release a water molecule, and so you can see the blue Oh here is coming from this Oh and the yellow H here is coming from this hydrogen. And so when water is released as we see here, that is dehydrating the molecule. The molecules are losing a water molecule, so the water molecules are being dehydrated. And in the process, it's synthesizing something. It is building a polymer, and so that's how the monomers are joined together covalently here as we can see. Now if we wanted If the cell wanted to do the opposite and break down this mon or this polymer into its separate individual monomers, then it's gonna need the backwards reaction to release, those 2 monomers and recall that is called hydrolysis. And so once again, the lysis part is all about cleaving and breaking things down. And so this bond here can be cleaved or broken by using water and that's what the hydro prefix is for in front of hydrolysis. It's saying water is needed in order to, cleave or break it down. And so notice that a water molecule is going to be added to the process and it's going to split the molecule in half. And so once again, the biggest takeaway here is that if a cell needs to build a polymer, it will perform a dehydration synthesis reaction. And if the cell needs to break down a polymer, then it's going to perform a hydrolysis reaction. And so that concludes our introduction to this concept and we'll be able to get practice applying this throughout our course as we move forward. So I'll see you all in our next video.
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