raise your hand if you're still working on the exam or on the quiz one person okay oh thank you where did PL go yes for okay um better okay good so um today we're going to continue um we're going to start um chapter six so chapter six is all about Energy and Metabolism um but we're going to kind of skip through the majority of the energy portions the first few sections of the book um that's just because you guys will be learning that stuff in chemistry anyway I don't want to be redundant and I want to kind of jump into more biology stuff as well um but if you do have questions or need something reiterated let me know okay so enzymes most enzymes like we've said before are proteins there are exceptions to the rule some RNA have catalytic activity we call those ribozymes but uh most enzymes are proteins and that's what you need to know for the uh scope of this class they are biological catalysts so a catalyst is something that speaks leads up a reaction or enhances a rate of something um and so you guys were working in last week's lab with the enzyme Catal a so anytime you see Ace as e at the end of a word it's most likely going to be an enzyme um that just infers that it has catalytic activity and so what an enzyme looks like is now we we've have a lot of cool technology to show us you know some 3D shapes enzymes and so you have the enzyme here but it has a specific site called an active site where a substrate will bind a substrate is the molecule or molecules that will undergo the reaction um and so the enzyme itself isn't changed or consumed in a reaction it's all about this substrate enzyme binding um in this site over here this is called the active site essentially a uh pocket or Clift for the substrate to bind um when the substrate is bound to the enzyme we call that an enzyme substrate complex and um usually you know these active sites are very specific for a particular enzyme so um you get a really like precise fit um not just anything combined there oh great um all right but um the way that this happens is usually when the sub straight binds it applies stress and it distorts a bond and then thus it will lower the activation energy so what does that mean so over here I'm showing you um a nice graph so on the xaxis we're looking at the course of a reaction and we're starting with the reactants and then we end up with products and this is the course of that reaction now the free energy is essentially the energy that needs to be put in for that reaction to run in blue here we see the activation energy which is how you know the the the energy needed in order for this reaction to run in blue it's without a catalyst um so it's without the enzyme it's uncatalyzed and so you see you need a much higher energy level to run this reaction to get to the product now when you do have a catalyzed reaction the enzyme included will allow you to lower that activ ation energy and the enzyme um and the reaction can run more efficiently and more quickly um and so one of the examples that we talked about way back in the beginning of the semester um was this carbonic acid it's a buffer that's in our blood and we need to continuously you know make it to make sure our blood remains at a neutral you know pH what whatever the blood pH should be close to seven and um our body makes this enzyme that basically converts water and carbon dioxide into this carbonic acid buffer now um this the enzyme that helps this is a Carbonic and hydras enzyme and so without the enzyme only 200 molecules of the carbon carbonic acid can be made per hour whereas this enzyme really lowers the activation energy so you can make 600,000 molecules per second so um it really speeds it up it makes things more efficient so enzymes are really important um and so I'll show you a little video and then I'll take questions on this enzymes are proteins that speed up chemical reactions in the cell a special region on the enzyme called the active site has a shape that fits with specific substrate molecules an enzyme works by binding to one or more specific molecules called reactants or substrates binding occurs at the active site the enzyme and substrates form an enzyme substrate complex the interactions between the substrates and the enzyme stresses or weaken some of the chemical bonds in the substrates these dresses encourage a link between the two substrates leading to the formation of a different molecule as a result of the chemical interactions within the active site a new product is formed the product is released from the active site the enzyme assumes its original shape and is free to work again although this reaction has specifically Illustrated the formation of a single product from two substrate molecules other enzymes catalyze the formation of two products from a single substrate yeah so enzymes are really um substrate specific and they change confirmation and so um they they are highly specific so here's an example of one type of enzymatic activity the cycle of how it works um so over here we're looking at a molecule of sucrose so sucrose is a disaccharide so it's composed of two monosaccharides glucose and fructose and they're bonded together over here with this Bond now when that binds to this enzyme um this is the enzyme SU hence the it's breaking down sucrose um this substrate will bind to the active site and it forms the complex um and then this binding will um Place stress on the this bond this glucose fructose Bond and so the bond breaks usually it's an water molecule that's added that will break that Bond and then you end up getting individual glucose and fructose products and so these products are released and then the enzyme is free to bind more suc sucros and uh sucros sugars to break down and so this is the cycle it keeps going um but that's not to say that an enzyme can't do the opposite where it takes two things and bonds them they can do different things but this is just one example of that questions okay just to um reiterate that an example of how enzymes function in the body is from the enzyme sucrase sucrase resides on the surface of the microvilli on the intestinal epithelial mucosal cell surfaces this animation presents a graphical representation of the way that sucra catalyzes the hydrolysis of the common disaccharide sucros which we know as table sugar into its component monosaccharides glucose or blood sugar and fructose or fruit sugar hydrolysis is accomplished because when the sucrose molecule binds to the active site of the enzyme the enzyme's configuration is changed so that the oxygen bridge between the two monosaccharides is exposed to water molecules in the solvent this exposure permits a water molecule to actually break the bond the oxygen bridge and attach the component of water an O to one of the monosaccharides and an H to the oxygen which is still attached to the second monosaccharide this effectively cleaves the bond between the two monosaccharides and converts the disaccharide into two separate sugars once this is accomplished the enzyme's configuration is changed back to the original shape the two monosaccharides float away and the site becomes available for another sucrose molecule to bind change the enzyme's configuration and be hydrolized this action can be repeated many times until the enzyme becomes denat is inhibited or just wears out all right um so those are just very simple examples of what enzymes can do but there are different types of enzymes and um they where they are located can also be different so they can be suspended in the side of plasm of a cell or they could be attached to the cell membrane um and organel but a lot of enzymes don't work by they form a complex with multiple enzymes we call them a multi-enzyme complex and basically it's subunits that work together to form a molecular machine um now these are pretty organized um so basically all the reactions are controlled as a unit and the product of one enzyme can then be delivered easily to the next enzyme um in that reaction so they work together um and so they're also you know they work together to make sure that there are no unwanted side reactions um those are prevented so it's pretty ordered um in in these complexes so um enzyme function though is sensitive to environmental factors so um usually you know the rate of an enzyme catalyzed reaction depends on the concentrations of the substrate and the enzyme how much do we have of you know the reactant that substrate and the enzyme that helps you know that really is what the rate of that reaction depends on but um if you think about outside factors any chemical or physical condition um can also affect the enzymes 3D shape and that can change the rate of reaction so generally the rate of an enzyme reaction will increase with temperature um but that only happens up to a certain point that we call the optimum temperature if you go above that Optimum temperature to much higher temperatures then the enzymes can be denatured which means that they break down and they lose that catalytic activity um so in the lab last week we tested the effect of um temperature and pH on enzymatic activity um and so for the one with the temperature I know there was some variability um but what you were supposed to see was low activity a lower amount of bubbles in the 0° on ice and then when you put it in the water bath at 40° That was supposed to be an Optimum temperature where you see a really high rate of reaction a lot more bubbles um that was variable depending on what you saw we're still optimizing the protocol but at 100° C at boiling temperatures I pretty much assume nobody saw any bubbles forming and that was because that enzyme the cataly was denatured in such a high temperature um that's not to say that there are some enzymes that work best at really high temperatures but this is more in the context of like a human body um and so um in just like a natural more natural world not in extreme conditions so most enzymes also have an optimum pH that ranges from six to 7 so what was neutral pH or 6 to eight so seven is neutral pH um and then um so when you guys I'm pretty sure this was consistent with almost everybody in lab when you guys tested the effect of the cataly with a pH of seven um neutral pH it ran really well but when we did it really basic or acidic pH of 11 or three respectively you probably did not see any catalytic activity or the bubbles so we're going to be doing more of that this week um measuring bubbles but in a different context this week so um just keep them keep that in mind now what would be an optimal temperature this is just a thought question for a human enzyme that is that works in the body what do you think would be a good temperature for an enzyme in the body h 98.6 degrees fenhe Yeah so um that and why do you say that it's like the average body temperature yeah so that's the average normal body temperature is a 98.6 so you would expect the optimal temperature for a human enzy to be around there um in in this course and in other future courses we usually do things using um Celsius so it would be about 35 to 40° C um but yeah that that's the the concept there now um like I said there are some enzymes that are U have an Optimum temperature that's going to be a lot higher so for instance um here in the red you'll see um the optimum temperature of a procaryote so maybe a bacteria that lives in a hot spring um an enzyme that's working in that procaryote would probably need a much higher temperature so it is specific to um what you're talking about for sure but um in the context of humans you would expect it to be in the normal range of temperature and pH and same for different um different things like pepsin and and Trin so those are or tripon those also will have different phes those are also en enzymes um Okay so last thing I want to introduce you to today is um Inhibitors an inhibitor is something that binds to an enzyme and it decreases its activity hence the word inhibition there are two types they can be competitive or non-competitive if it's a competitive inhibitor it's self-explanatory it's going to compete with the substrate for the active site it interferes and it binds in that area um so the substrate cannot bind in the non-competitive inhibitor example we also call this alisic inhibition um basically the um the the inhibitor will bind to the enzyme at a site that's not the active site we call that the alisic site and that causes the entire enzyme to uh change shape and it's unable then to bind to the substrate so in the competitive inhibitor um situation you you'll notice here that the inhibitor kind of has a similar um shape as the substrate this end of the substrate for binding so they're going to be more similar whereas this one isn't the same because it's binding somewhere else um but I will leave you with that here as a little introduction to Inhibitors we'll finish chapter 6 on Wednesday and we'll go on to chapter 7 questions yeah so how negative how negative or how negative so they can vary they can be really like negative negative inhibition is basically your but there are that [Music] [Music] [Music] yeah [Music] abely I don't think [Music] [Music] off