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Enzymes (7:43)

Added Sep 23, 2019 •

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Discussion of how special types of proteins, known as enzymes, influence chemical reactions.

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so in the last video we said that the final function of proteins for enzymes enzymes are also known as catalysts these are proteins that speed up chemical reactions and help him take place more quickly without a chemical reaction they would all take place too slowly for life to exist so we need enzymes to kind of help with each of these processes to Aiden speed them along some words that you're going to need to know to understand enzymes are that work on is called a substrate so in example that my human biology kids are doing with their lab the enzyme was in their saliva the substrate or what they were trying to break down to have the reaction with was starch in the form of cornstarch in water so substrate is whatever the enzyme works on the active site is the location on an enzyme where the substrate binds to it and connect active site for every type of enzyme has a thick shaped so that it can fit to its substrate we're going to look at this in just a second more specifically but just remember from the last video that I said all proteins have a specific shape and that shape determines their function so once again with enzymes we see that the structure of that active site is going to determine what substrate it can connect to the product is what you're left with at the end of the chemical reaction so in the case of starch and our saliva the productivity maltose it takes that large which molecule and breaks it down into the disaccharide units known as maltose 4 things that you need to know about enzymes that are specific like I just said each of them has its own special active site with its own specific we call this the lock and key model every enzyme has an active site that fits perfectly to its specific substrate so one enzyme can't just work on anything it has its own substrate that it matches with so you just like you couldn't use one key to open every person's house on one street only one type of enzyme can work on one type of substrate so enzymes are all specific to their own job the second thing you need to know about enzymes is that they are reusable they can do the same and over and over without being used up or lost and their unchanged by that reaction so as one of the enzymes is just you look at just one protein one as I'm breaking down starch once it does that job start turns into maltose it can go back and find more starts to break down immediately after so the enzymes are reusable to keep doing the same job over and over and over again until you can see a good example of what an enzyme looks like with its specific active site that very specific shape there and it fits to its substrate the molecule that is trying to break down or work on so you can see how those fit together like a lock and key to go perfectly together this is what we call an enzyme substrate complex because they are bound together the active site and that's when the chemical reaction is actually taking place once the reaction is done you're left with your products and important thing to note with this picture you see how the arrows go both ways this means that enzymes can not only break things up. it can also put them together so you can just as easily start over here with these two molecules being your substrate and going through a chemical reaction like dehydration synthesis for example when you put small things together to make a bigger saying they take tattoo smaller molecules into that reaction create a new product so this can work in either direction the third thing you need to know about enzymes is that they can denature or change shape in harsh conditions so every enzyme has gone off to 4 best pH and temperature just like people has a temperature that we need to stay roughly in the range of in order to be healthy to reason for that is if our temperature goes to higher to the proteins in specific enzymes inside of us are going to start falling apart and losing their shape and the proteins if they lose their shape that also means that they lose their ability to function because shape determines function so every enzyme has its own best pH and temperature it works at and if you push it beyond that range it's going to fall apart and denature and it will no longer be able to do its job sometimes permanently the fourth and final thing you need to remember about enzymes is that they catalyze reactions or they they do this by lowering the amount of activation energy which is how much energy is needed to get a reaction started if there's no enzyme present in a solution the reactions activation energy work into it to get it to take place but when the enzyme is present its speeds up a chemical reaction by lowering the activation energy the cell has to put less energy in itself if you think of this as trying to eat a Saltine cracker how to completely dry with no saliva and not drinking any water it would take a while to get through something so dry on your own would take a lot of energy to chew that be able to actually swallow all of it but with saliva and with the water in it and all the enzymes there that process is sped up so we have to put less work in ourselves so this is what the activation energy for a given reaction would look like if there was no enzyme present to go from the reactants or are starting substrate all the way to products is going to require a lot of energy however if we use an enzyme we no longer need this much energy we only need to put in a little bit of our own so this lowers the activation energy for that given reaction this is just another picture demonstrating that if you are trying to do a reaction without an enzyme present you're going to have to put in a lot of work a lot of activation energy on your own but with an enzyme present it lowers that it makes it easier so we as humans are a living organism doesn't have to use its own resources and energy to get that job done it's taken care of mostly by the enzymes I don't know about enzymes there are four factors that will affect how well they work those are pH temperature the concentration of the enzyme in the concentration of the substrate so if you change any of those it can make it more or less efficient for example of temperature if the temperature of a solution where the enzyme is gets too high the enzyme is going to start to denature and I won't be able to do its job because once they shape of it changes in the shape of that active site changes it won't be able to bind to the substrate anymore for the concentration examples think of it again without Saltine cracker if you increase the concentration of enzyme that you go from having no saliva in your mouth to having a passel of spin it's going to make it easier to eat that Saltine cracker if you increased the concentration of the enzyme in the direct opposite fashion the concentration of the substrate also matters there was a difference in how quickly and efficiently you can eat one Saltine cracker versus 20 saltine crackers because those are the substrate that's what you're trying to break down if you increase the substrate you're also going increase the amount of time it takes the enzymes to do their job so make sure you understand active site substrate and what an enzyme is the Catalyst make sure you understand those four facts about them there reusable how they don't change their shape and make sure you understand what activation energy is if you have any questions please come ask me or go back through this video and try to figure out exactly what you need to know

Uploaded by Laura Lovelace.

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Enzymes (7:43)

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