so now what we're going to talk to and talk about is energy without energy there would be no life on the planet and as we think about stuff life these biologically important molecules without getting into any theology at all just staying scientific because this is a science class if you want to talk theology with me we'll talk about that all day long we'll just do it after class but when you look at the stuff that is present in the universe we all came from stars stars and their burning energy created these heavier and heavier atoms that exploded out into the universe to produce the carbons and the oxygens and the nitrogen's and so we're a collection of Stardust and when you look at life in general on the planet and you look at all energy all of our energy that we have comes from a star and what is our star called the Sun all energy that we know comes from the Sun and it's a great thing we have the Sun and we live a certain distance from the Sun they call the Goldilocks zone that's what astronomers do when they're looking for planets around other stars but all of that energy comes in is required for cells because we have to maintain a body temperature we have to polymerize certain molecules we wouldn't be here without the movement of us spermatozoa that fertilize an egg concentration gradients charge separation we're going to get to those shortly but this is all energy that happens in all of your cells each and every day and it all starts with the Sun and we have certain groups of organisms on the planet autotrophs why do you think there's a green box with a P in it through our autotrophs plants photosynthetic organisms that capture the energy from the Sun those photons of light and they convert that energy into chemical energy and they store it in chemical bonds of molecules not the least of which is our six carbon ring good friend called glucose then we have herbivores that come along they eat the autotrophs then we come along and you got it like a good steak right so we get the energy from the herbivores and we start this process over and over and over but what I want to point out in this conversion process from autotrophs herbivores carnivores decomposers we don't transfer all the energy some of it is lost so it's not a 100% efficient process and we say the energy is lost it doesn't mean it disappears it doesn't mean it's gone because we have two very fundamental laws of physics and I know this is not a physics class but this completely relates to looking at energy the first and second law of thermodynamics the first law and you notice that I've got an underline here that says change when you think of the first law want you to think of change because energy by this very first law it cannot be created and it cannot be destroyed it can only be changed so the energy we get from the Sun we change that plants change that animals eat the plants they change it we eat plants and animals we change it some we don't get to use directly some as lost as heat but the energy never goes away it's simply transformed which always makes me curious because then variably I always get this question because I go to church but I'm a scientist and a lot of people always ask me how do you reconcile the two well I always talk science because this is a science class but this very first law energy can't be created or destroyed well where'd all this stuff come from the first law says we shouldn't be here did it just always exist I'm not trying to provide you answers I just like asking questions but that's that's a big that's a big one where did everything come from when way back so anyway we'll leave that one alone because it's making my head hurt first law change you only change energy the second law now we mentioned entropy earlier that's just a term I wanted you to be familiar with we're not going to spend a lot of time trying to really understand energy other than it's this disorganization in the universe but since everything wants to become more disorganized the second law says you know we're going to lose energy and heat as we transform energy some is going to be lost in heat you just have to it's like when you transform energy somebody gets a commission does anybody ever worked in food service and stuff and you've got to give a part of what you earn yeah have you ever had a job and you see FICA getting most of your check well I guess it's kind of like this one yeah you're going to get lost in taxes so you can only change the energy and it's not going to be a 100% efficient transformation someone's going to be lost but regardless where does it all come from where does all of our energy come from the Sun that's where it starts so at some point we have to begin to get down to our cellular level our organelle level and our molecular level and so as we look at this illustration understand what we're looking at here in the green box and photosynthesis this is an organelle that you find in plants and some fungi this is called a chloroplast this is where photosynthesis takes place so photosynthesis is where the energy of the Sun is captured you actually have two steps of photosynthesis you have a capture stage of photosynthesis and then that energy is used to take carbon dioxide and attach the carbons together and produce glucose and that second stage is going to be our energy stored stage now photosynthesis gets a lot more technical than that but that's all we're going to do photosynthesis captures energy and it stores energy and chemical bonds of glucose now once we come over to the animal side in the animal side we are going to take the glucose where the energy was stored and we're going to transform that energy we're going to transform that energy using oxygen so this is aerobic introducing some terms that we're going to put in a better picture and look at even closer probably on Wednesday but we take the glucose and oxygen and we transform the energy we take the energy out of the chemical bonds of glucose and we put that energy in the bonds of ATP adenosine triphosphate this is the same a that we see in our nucleic acids we're just using it differently so the bond of energy between the second and the third fossa fate where we get the triphosphate part that's the energy that we're getting from those chemical bonds of glucose that originally came from the Sun you see that so I like to say ATP the energy currency of all cells every cell uses ATP it's like your debit card if you've got money in the bank your debit cards ATP you can get work done with it you can buy stuff but if your debit cards like mine and there's no money in the bank then my debit card is a DP I don't have that third phosphate I don't have the energy stored there I guess I could use it but I go to jail right no I it's not gonna get much work done with my debit card so ATP this is the form in which we are going to use the energy to do everything that our body does muscles are going to contract nerves are going to send signals immune cells are going to crawl around that's where we are getting the energy from the Sun into ATP so that our cells can use it for everything they need to do now for us to be able to do that we have to understand some foundational principles of energy and the two types of energy are potential and kinetic and I think we're pretty good with that so this is kind of review a potential energy is a substance or an activity in which you have stored the energy and once you release that energy you can get work done and so when you pull back a bow does this get in close to deer season right you pull back the bow that bow has some potential energy in it all you have to do is let go of that string and you're going to convert that potential energy into kinetic energy and get movement for your cells some of that potential energy is going to be in concentration gradients on either side of a plasma membrane we're going to see this a ton and when you think of concentration gradients relative to cells and membranes I want you to think of a hydroelectric dam you dam up a river and the water stacks up on the lake side the water goes down on the river side do we just leave it there so we can go waterskiing and fishing now what did they use the dam for energy to make electricity how do they do that the level of the water on the lake side has a potential energy because of gravity gravity's wanting to pull it down hill so when they open the gates and allow that water to come through the turbines that the water then spins I mean this is like an old-fashioned waterwheel you've seen those in some of the old movies it spins that turbine that turbine is attached to a rheostat that produces electricity so you turn the potential energy of the water building up to kinetic after you let it flow through your cells are going to build up concentration gradients of ions and when you open a channel and they flow through you're going to be able to accomplish work so if you see the potential energy at the cell level and again compared to what's happening at the lake chemical energy this is another type of potential energy because here's our six carbon glucose molecule and it's showing these little yellow kind of star explosions because again the energy from the Sun it's what is stored between these bonds between our atoms that we then transform capture and use as ATP so that we can cash it in when we need to do things like work our muscles and we refer to that as the chemical energy the energy of those bonds all of our atoms are held together in such a way that they all have a potential kind of energy that we call chemical energy so we get glucose our cells break it down we go through respiration which is that transformation and capture of the glucose energy and making it an ATP then we use ATP so we can accomplish kinetic energy our heart beating those muscles contracting kinetic energy here we have hearing those sound waves impacting on our tympanic membrane what's another name for the tympanic membrane eardrum that's going to be a type of kinetic energy mechanical energy because you have that vibration we have light energy impacting on your retina your retina is going to convert those photons of light into chemical gradients that will signal your brain and then of course we have those other electrical chemical signals that are going on in our nervous system our nerve cells or neurons have that type of electrical energy now since I mentioned neurons I wanted to show you this this is our potential energy picture where we have sodium ions stacked up on one side of the membrane much lower concentration on the other this is how neurons work to send signals when that nerve cell body receives a change of electrical signal which means you need to send a signal down the line these sodium channels open sodium flows from the outside of the cell to the inside of the cell which changes the electrical distribution of those charges which changes the voltage and so this is a measure of the voltage change that happens and that change flows down that part of our neuron called the axon and it's illustrated graphically as this electrical wave that goes down the line all that wave is is a changing of your sodium gradients and when we get to nervous system we're going to see also a change of our hassium gradients so do you see in this particular example we started with a potential when the cell was at rest and by allowing the kinetic energy of sodium moving we can send a signal all the way down that cell and that signal may go from your spinal cord to your big toe or back so potential and kinetic now to understand this conversion process to understand the catch or even in photosynthesis which it's not the scope of our class but we have to understand chemical reactions are most of you also in chemistry this semester and one way shape of form or you will be so with a chemical reaction we start with certain molecules we may call them the reactants and as we undergo a chemical reaction we're going to convert these reactants into some form of product and typically we're going to be breaking chemical bonds causing the chemical bonds to rearrange and we're going to form new chemicals at the end of the process so under certain conditions bonds can be broken molecules rearranged and we end up when we started with hydrogen peroxide now we end up with water and oxygen so again chemical reactions breaking bonds rearranging reforming new molecules now when we put it on paper like in a chemistry class we draw it out like this two molecules of hydrogen peroxide yield two molecules of water and two molecules of oxygen now when you write it out everything has to balance you you you're not going to lose Adams's you're not gonna lose ions and the important parts of these reactions are the arrow which indicates okay which direction are we moving the reactants this is a stuff that's around before the chemical reaction started the products what happens after and oxygen of the water is also a product I should have colored that purple as well and again as you're trying to balance these out in chemistry class here we have four atoms of hydrogen as a reactant here's our four atoms here we've got four atoms of oxygen we're going to put two of those atoms with our water and there's two left over as simply o2 that is a good balanced chemical equation so we left off last time as we were talking about chemical reactions so we had a very simple one to begin with I like to start simple and build and get more complex if you start out too complex and you don't understand well you missed the bus and you're never going to get back on so as we look at our equation we have two molecules of hydrogen peroxide it undergoes a chemical process and we're gonna explain a little bit more when we get into some specific examples but in this chemical reaction the hydrogen peroxide breaks down into water and oxygen now remember what you start with are called the reactants what you finish with are the products including water but in a chemical reaction the arrow can go in which direction I heard somebody say either there can go in either direction but it can also do one other thing it can go in both you see how those words are different either sort of signifies a single direction but if you do both at the same time it is a reaction that is reversible so that's just sort of a broad understanding of a chemical reaction and when you do in fact get into chemistry class you're gonna have to balance out the equation by keeping up with the atoms we're not going to do that kind of balancing and stuff this is just again to introduce this concept to you because as we get into using energy and utilizing energy we have a much more complex equation and even though it looks really bad let's let's kind of step through it just a little bit when you see an equation that says see h2o what category of macromolecule are you automatically thinking about carbohydrates that is the basic formula for a carbohydrate one carbon two hydrogen's one oxygen and when we look at the subscript outside of the parenthesis that tells us how many carbons are present so when you write the equation C h2o with a subscript six outside which specific carbohydrate are we talking about that has six carbons glucose so you can write it that way or you can write it c6 h-12 o-6 it means the same thing so in our equation and starting on let's go ahead and start on the right side because this is photosynthesis the photosynthesis we're going to take six molecules of carbon dioxide and as we talked about balancing the equation we have six molecules of co2 how many carbons do we have six molecules of co2 how many molecules of carbon are there six so photosynthesis is going to take the carbons in these six individual molecules and it's going to link them together into one six carbon molecule called glucose that's really what photosynthesis is about and the energy is going to come from where the Sun because where does all energy come from initially anyway the Sun and that's how plants do that soon our equation plants take carbon dioxide they take water and the energy that we have designated here is coming from the Sun and using that energy they assimilate these carbons into one molecule called glucose now when you have an equation and we see the arrow pointing away from the side where you see energy so in this case if the arrow is pointing toward the left and energy is on the right meaning energy is there before and must be there so the reaction can occur what would energy be in this case a reactant or a product it's a reactant and so to have this chemical reaction take place you have to put energy into the system that kind of equation is called an endergonic used to be called endothermic but now the term is endergonic reaction meaning you've got to capture and use energy to make that reaction happen so photosynthesis energy in so that we can take our carbons and linked them together into one molecule called glucose now remember that energy transfer is not going to be 100% efficient you're going to lose some of that energy in the transfer which law of thermodynamics states that second you had a 50/50 shot right there's only two it's the second the first one says you can't make something from nothing so here we've got our energy in and the end from the Sun is captured and stored in the chemical bonds of glucose now we're going to go over and that happens in our chloroplasts by the way in our plants now we're going to take the glucose and we are going to begin to process the glucose in our cells and the mitochondria in addition to some other enzymes that are happening in the cytoplasm are going to begin to break down the glucose and recover the energy and that's our reaction here we see our glucose we're gonna have to use oxygen so this is aerobic respiration get familiar with that term aerobic you see those are both to the left of the arrow arrows moving toward the right so these are now our reactants and after aerobic respiration we are going to break the glucose down into what six molecules of carbon dioxide we're going to produce six molecules of water and what is being released energy do you see how the equations are practically the same what's the really only difference the direction of the arrow so if you remember the components of the equation and you know that an endergonic putting energy in the arrows pointing away from the energy and when the arrow points towards the release or the production of energy that is called exergonic or exothermic so these terms really do strictly point toward are you having to use energy for the reaction to occur are you releasing the energy because the reaction occurred plants store the energy mitochondria release it now why didn't I say plants toward animals release it because guess what plants have in addition to chloroplasts they have mitochondria as well all cells are going to have that they have that for the energy production so do we understand our balanced equation energy in endergonic energy out sargon it that's just sort of foundational to where we're going because to understand how we can build carbon dioxide into glucose and tear glucose down into carbon dioxide it's not enough to understand the chemical reactions because these will not occur efficiently enough for life to exist without these all-important proteins called enzymes now first of all let me be very clear enzymes are not magicians you know magicians appear to make something happen that shouldn't happen the one that I'm most fascinated by are the magicians that appear to levitate off the ground have you ever seen those that freaks me out I wish somebody would tell me how they do that enzymes aren't magicians they're not going to make something happen that couldn't normally happen all enzymes can do is take a naturally occurring reaction and help it happen easier and because it's happening easier it's going to happen faster that's all enzymes do they're not going to make a reaction happen that wouldn't normally happen in nature and so we say enzymes are catalysts in that case they facilitate naturally occurring reactions they increase the rate of naturally occurring reactions but you see the key to all this is the reactions are already going to happen enzymes just help that so if we look at a chart here our reactants and this is sort of energy so here our reactants here's our products notice the energy of our products is less than the energy of our reactants and so Energy's being released Energy's being given off what kind of reaction did we just label in the last slide means energy given up exergonic you know one way I remember that the first part of exergonic X sounds like exit which is to leave so if you remember exit leave exergonic energy leaving then the other one has to be energy in right so that's how you can remember that but notice it's not just a straight Hill down you've got this big hump do you actually have to put energy into the system before you can release the energy and this additional energy up is called the activation energy for the reaction to occur now that is an uncannily action that you're looking at that's what naturally occuring act reactions would have to do many of them would have to put that energy in and sub substantial bit of energy before you could start downhill and get to the products so the way enzymes function as catalysts is they reduce this activation energy now in this illustration you see the blue line that has the higher hump that's the higher activation energy that is an uncapped reaction no enzymes present the red line that is a much shorter hill to get over much lower activation energy that is a catalyzed reaction because we put enzymes in now let's go back to our example of hydrogen peroxide you remember what hydrogen peroxide broke down into in that other very simple equation it broke down into oxygen and water so if we just follow an uncanny lized reaction if we just put hydrogen peroxide in a beaker set it on the counter in your bathroom is that really going to effectively change into water and oxygen everybody shake your head no to add the energy to get up that activation energy hill you'd have to heat it up put energy in right but if you add some hydrolase enzyme and you leave that beaker at room temperature that's what's going to happen why does it bubble up like that what are you producing oxygen you're producing oxygen it's a gas so it's going to come out of solution you see the difference this is uncatted eyes no enzyme it will happen eventually if you give it some energy but if you don't have that much energy around but you've got some enzymes boom you can make it go and you can make you go a lot faster and a lot more efficiently that's the use of enzymes now there's more than just one enzyme in the world there's many many different categories of enzymes we're going to give you five categories in a bit but what I want you to understand about enzymes is in addition to the fact that the majority of enzymes are proteins now there are a few that are made of RNA and we're really not going to get into those for our purposes here all enzymes or proteins is that good and so proteins are going to have a very specific shape right we talked about that you know our four levels of protein organization I mean you can follow the numbers primary secondary tertiary and quaternary so with the specific shape of our proteins called enzymes part of that means is a specific shape that is going to bind to one of our reactants in our chemical equation and we changed the name a little bit for those reactants because if something that's going to bind to an enzyme we don't necessarily call it a reactant now we call it a substrate but it's still the same thing as a reactant it's what happens before the reaction occurs but because of the shape of our enzyme there is a specific pocket that is going to be just the right shape for only one specific substrate that pocket is called the active site now many of us in here have cars and many of us will all of us that have cars have a car key but as your car key gonna fit her car no it's not a specific match so not every substrate substrate can bind to the active side of just any enzyme it is going to be specific there used to be a lock and key sort of analogy to enzymes and I still like to think of that as far as binding of the substrate to the active site where that material is going to be processed broken down built up some change is going to happen because of that active site and because of the enzyme but it's more than just a specific fit because what we understand now is that when you have an enzyme that has a very specific active site when the substrate as you can see in the lower right when it binds to the enzyme the enzyme changes shape remember we said a lot of those hydrogen bonds are there to provide the flexibility for the enzyme and as the enzyme changes shape because the substrate bound do you see how we've stretched out the substrate itself and now we've made it a lot easier for the enzyme in this particular illustration to cut that substrate into two separate pieces so instead of a lock-and-key now we refer to this as the induced fit model there's a fit between the substrate in the active site and the binding induces the enzyme and the substrate that is now bound to the enzyme to change shape and that's that change of shape that lowers the activation energy to make the equation to make the chemical reaction easier to happen and in many instances the active site of our enzyme it's going to have very specific amino acids with very specific properties and it's because of those important amino acids in that active site that's what facilitates the binding and the change of the conformation over the entire protein called the enzyme now understand this word conformation this means shape when you change conformation that means change shape it's just a big fancy scientific word for that so make sure you note that because you'll hear that quite a bit and biochemistry stuff and anatomy stuff especially as it relates to enzymes now there are six categories of enzymes we're not going to learn specific examples of all of these I simply want you to be familiar with these six categories in a very fundamental sense because there are a lot of different enzymes and a lot of different ways to characterize enzymes the first thing you're going to notice about enzymes when you hear the name of an enzyme and this word ends with ASE ace your little warning light should be going off okay this is an enzyme what does it do and typically the first part of the name tells you what it does and many enzymes are catalysts a break things down so if I were to tell you there was an enzyme that was called dnace what do you think that enzyme does breaks down DNA what about RNAs breaks down RNA what about a protease breaks down proteins what about a lipase breaks down lipid you see that's fairly straightforward but then we get into some of these other categories oxido reductase well these enzymes are going to use oxidation reduction reactions adding or taking away electrons to change molecules transferases we're going to transfer atoms or molecules between structures hydrolases you're just going to cut a molecule into two pieces like we saw in our illustration and isomerase is going to change a molecule such that it's going to look like the mirror image of itself and when I talk about mirror image are your hands identical okay we're not talking my finger prints but are your hands identical no because this hands got the thumb pointing toward the right and this hands got the thumb you see how they're mirror images though these would be isomers your hands are isomers of each other and these enzymes are good at taking a molecule and flipping parts to present a mirror image copy that's an isomerase a ligase bless you a ligase links two molecules to death together DNA ligase links two molecules of what together DNA that's going to be an important part when we get to cellular replication and and DNA replication that that's a critical part of your cells dividing and then finally these lai aces this is a removal of a specific group now there's some overlap to some of these some of these sound similar so don't don't panic if you don't know a specific difference between these I mainly want you to be familiar with the names of these six categories and again this is just foundational stuff that you may run into later but it's important to understand the diversity of enzymes just like man there's an extreme diversity of proteins alright now this is a chart I know you can't read it the words are small this is a chart that again shows those six categories gives you some examples gives you a little bit of more explanation and shows actual chemical reactions that these enzymes facilitate use the chart only if it helps you if this chart only if you're looking at and it starts to confuse you or starts to make you anxious don't look at it that's I'm not asking you to memorize this chart is that is that clear this is just help you to understand if you wish to better those six categories of enzymes now what's more important necessarily than just the categories is how do we regulate enzymes they're facilitating chemical reactions that's going to be a critical aspect of maintaining our balance for ourselves and our tissues our organs and organ systems and what's that big word that we have to attain balance what is that word homeostasis so enzymes are a part of that and regulating how fast or how slow they facilitate these reactions or if they do them or if they don't that's a huge part of this so we're going to step through these five means with which we regulate enzyme activity and the speed with which they in fact facilitates these reactions so first substrate level regulation what what is another word for a substrate what did we say a substrate was a reactant the substrate is a reactant so this is a little kind of changing our perspective we've been focused on the enzyme well now we're going to focus on the substrate but do you see how that can impact a rate of reaction if you have a ton of enzyme and no substrate is the reaction going to happen no it's not but I think you can also see as you increase the concentration of substrate not increasing the number of enzymes you can see how our reaction rate increases how many that's just logic right but you notice we get to a certain constant tration and the enzymes can't work any faster you've saturated the enzymes the substrate starts to stack up and sometimes this is a difficult concept so I listed some old television show to help with this so imagine Lucy and Ethel are the enzymes the reaction that they're facilitating is wrapping the candy have you seen this clip before the belt starts going faster and it starts going faster and they're not able to handle that amount they're still only wrapping a certain amount even though there's more and more and more but does that make sense though as you get more and more substrate the substrate has to line up and wait because the reactions the enzymes can't make it go any faster and that's why you see that plateau now if you did have a ton of substrate and you reach that plateau of enzyme activity but your cells are your body needed more product what is something the cell could do to increase the rate think about it logically if you need to increase the rate but the number of enzymes you have are working as hard as they can how can you make it go faster make more enzymes make more enzymes so that's another way the cell can enhance its activity if it needs more enzyme and you've got plenty of substrate the cell can always make more enzyme and make the process go faster produce more product more quickly now another step of regulation is temperature