Energy Sources and Generation

Hi in this video, we're gonna be talking about energy sources and consumption. So first, let's talk about energy sources. So where do sales get their energy? And what terms do we use to describe energy and cells. So the first thing is that in order to survive, cells need a constant source of energy. Energy is what allows them to live. It allows them to undergo all the chemical reactions required for life. And so in order to constantly be doing those chemical reactions that allow cells to survive, they need the energy for those chemical reactions. Now before we get into energy. In terms of sells your book and your professor are probably going to describe energy just in terms of science. So a lot of these, especially this first section here is going to be talking about energy and typically a chemistry type of perspective, but I'm going to introduce it here because your textbook does and your professor probably will. But then I'll get more into what energy means in terms of cells and cell biology. So the first thing is let's talk about the second law of thermodynamics and that just says that the disorder in the universe only increases. So what does that mean? That means that things happen that destroy the perfect order of the universe. So for instance, an example I'm going to use later is this card tower. So cards don't spontaneously form into these nice towers. Right? The disorder of the universe includes these cards most likely falling down and coming into an array. Now we can use the example of a card tower, but pretty much everything in the universe is has this nice form of a card tower but that's not usually how it works out right? Usually the card tower gets knocked over, the cards go everywhere. The same happens for chemical reaction sells where anything else outside of cell biology as well, disorder or the mess of everything is always increasing. And so to measure that increase of disorder so that increases sort of messiness. We use entropy measure of the systems disorder. Now, entropy is a term here that your book is going to describe, your professor is going to mention, but we are not going to talk about any other time in cell biology. They just need you to know this now because it's important concept in science. So make sure you understand the definition now in chemistry, you're gonna focus on physics, potentially you're going to focus on this a lot more. But for cell biology, I'm just gonna introduce the term because that's how it's supposed to be. And then I'm not ever going to mention it again. And so in terms of how we relate entropy to anything else, we say that system. So that can be anything. It could be a card tower, a chemical reaction to sell etcetera, etcetera, etcetera, spontaneously change towards more entropy, which equals more disorder. So like the card tower, the car tower is going to spontaneously fall, right, Somebody's gonna knock it, the wind will not get over. And so systems are going always towards more disorder. And that means more entropy now, when because the because the disorder in the universe is only increasing, we're getting more and more disordered. And so in terms of a living cell, a cell has to generate energy, right? Because it has to have energy to survive. So it has to generate that energy in an environment that's growing more and more disorder. So what does energy mean? Well, the sort of chemistry definition of energy is the capacity to do work. That's the that's the definition you're going to see in your textbook. What does that mean in terms of cells? Well, energy is what the cells used to undergo changes whether those are chemical changes like chemical reactions, physical changes changing the structure of the cell or anything else inside the cell. And this energy is used using these changes to create more order in the cell. So if we just let the cell become more and more disordered eventually it's going to fall apart. And that's not going to be useful for our survival. So energy has to be used in the cell to keep it together to keep it ordered to keep these reactions going in a sort of sensical way. Um And so energy is in this disordered environment and it's frantically trying to keep everything together and keep as much order as possible. So in terms of cells, energy is used to keep the cells alive and keep them structured properly and keep them moving forward, growing, dividing everything that they have to do. So how do we measure energy? This is another one of those terms we're going to mention here because your textbook does and then we're never really going to talk about it much from here. But let's just mention it here. We measure energy using calories which of course you all know about calories. The calories you eat. If you're on a diet, you're probably concerned about them. And a calorie is just a measurement. And what it measures is how much energy is required to raise the temperature one g of water by 1°C. So when we eat our food, we're not really thinking, oh this were thinking oh this thing has 100 and 10 calories. But what that means is that's the energy required to rage. 100 and 10 g of water by one degree Celsius. So so that's calorie. And then sometimes you'll see this as a jewel. Especially chemistry. If you're taking chemistry right now you'll see this much more prevalent and a jewel equals 0.239 calories. In cell biology. If we mention it at all, it will be in terms of the calorie. But really outside of this chapter, you're probably never going to see calories or jewels ever again in terms of cell biology but they feel like they need to present that information to you. So I am as well. Um So here's the example, we've already gone over this um demonstrating entropy and energy. So the entropy this car tower wants to be more disordered. The cards just kind of want to just fall all over the place and be messed up the more disorder. But if you put in energy, if somebody comes over and puts in the work necessary to build this card tower then you can create more order in terms of this card tower. So some of the basic definitions of energy and entropy and disordered. But a lot of times in biology we're not so interested in some of these like chemical uh ways of describing energy. We're much more interested in what the energy does inside the cell. And so there's two types of classification of energy potential and kinetic and they differ based on how the energy I guess is being used. So for instance potential energy is stored energy. You can kind of think of that as like a bad right? So that battery has so much energy in it and it's ready to be used. But if it's not plugged into anything it's sitting in the store waiting to be bought. That is an example of potential energy, it's not being used but it's being stored. Whereas kinetic energy for example is energy due to motion. That energy is being used. So if you plug that battery up to say a remote control for the tv and you're using that remote control, that energy is being flooded through that remote control, it's being allowed to be used um what's actually being used? It was actually moving in that is electrons. And these electron movement is allowing that energy be used for a purpose. So potential is that stored energy in that battery and then kinetic is when the battery is used. But what about it sells? This is cell biology. We're not talking about battery. So what's some examples of kinetic and potential energy and kinetic energy? Remember the moving in energy. Examples of this in cells include things like heat, light and electrons and heat is constantly being given off by the cells. That's why we have the body temperature we do. Um Light is constantly coming in and interacting maybe not so much with us, except in our eyes, but in other types of bacteria that may be depend on light and especially for instance, plants really depend on light. Um and so that's an example of kinetic energy and then always electrons, electrons are constantly moving. Um in our cells and our proteins, they're constantly being exchanged to create chemical bonds or used to create more energy are used are using energy to move. So this all is examples of kinetic energy. Things that are moving things that are being released. Things like that. So what is the examples of potential energy in cells, potential energy is like those batteries, they're being stored but not used. So, potential energy is energy found in chemical bonds. So, if you have these molecules, they're not really interacting with anybody else, they're kind of stable off to the side, maybe they're building a structure but not necessarily being broken or used. That's exactly like that battery. It's just being stored. Um a good example of this that we actually are gonna talk a lot more about our membrane concentration gradients. So what does that mean? That means that we have a membrane which we'll talk much more about and we have a concentration gradient. So what does that mean? That means that one side of the membrane has a lot of molecules, a really high concentration and one has a really low concentration and so watch the cell. So what this is is an example of energy storage in the cell because we all everything wants to move from high to low. And we'll talk about this a lot more. And so, but until it does move, so until there's a way for these concentrations over here to move across the membrane. This is a way to store energy. There's a lot of energy in this example here, exactly like the battery where before it can be transferred across the membrane, it's being stored in that battery. So, this is a really important example of potential energy and we'll talk about membrane concentration gradients a lot moving forward in cell biology. So that's kinetic and potential energy. Super important. I'll show you some examples of that later. Now there's another term you need to know again, this is a term we're going to introduce here, but we're not really going to talk about it much after that. And this is sales must do work. And so what is work? It's the measure of energy. So how much energy is needed to move or affected object, How much energy is needed to break a bond? How much energy is needed to form a bond, How much energy is needed to move things across the membrane etcetera, etcetera, etcetera. Now there's a lot of different types of work. All right here. I'm listening like, I don't know six, I think is right there. And these are terms that I'm going to introduce here. And you're never gonna see again. I'm never going to say. Um, for instance, a moving molecules across the membrane, for instance, a membrane concentration gradients. I'm never going to describe that as work. Even though that's what it is. And I have things here, synthetic work that changes in the chemical bonds, breaking or forming mechanical work. Changes in cell structure, whether things are moving around the cells, changing structure concentration work, electrical work. We have ions moving across the membrane, we have heat maintenance of the body temperature and then a fancy term called bioluminescence, which is producing light. Now, I'm never going to mention these work terms ever again. But they still are super important for these regions because you need to understand that energy is required to do these things. Energy is required to break or form chemical bonds. Energy is required to change the cell structure, move molecules across the membrane, move ions across the membrane now, maintaining the body temperature and producing light in those organisms that can produce light. All of this requires energy and that's what we're going to be talking about in cell biology. All of these different processes that happen in a cell are required for a cell to survive and they all require energy. So, a lot of cell biology is going to be telling you, okay, well, we're going to talk about moving this one molecule across the membrane and this is where it gets its energy from. And so I'm never really going to talk about work again. That's going to be a word that you use much more in chemistry than cell biology. But mentioning it here because your textbook mentions it here and you do need to understand the connection between when you talk about work and chemistry and you talk about energy and cell biology because they are intricately connected. So, let's give an example, last example, before we move on, potential energy and kinetic energy. Now, the example that your book is going to give you is this and you've probably seen this at some point in chemistry if you've already taken it. And the example is you have a cliff, which is this is a cliff and there's a ball right on top of the cliff and then it rolls off to the bottom of the cliff. Right? So what's the example of potential energy? Well, potential energy is before it's moving. It's when it's at the top of the cliff but it can be kicked off or knocked off to fall over the cliff. But before it falls, when it's just sitting on top of that cliff, it's exactly like that battery, it's not moving, it's not doing anything but it has the potential to do that the same with the battery. The battery has a lot of energy in it but it's not using it, it has the potential to use it when it's plugged up. So, potential energy is when the ball is sitting at the top of the cliff. But when the ball is actively moving and it's falling through the air off the cliff, that's the example of kinetic energy the same way as if you plug up that battery and you're using that remote control the exact same thing. So this is the example you're gonna see in the book. But I wanted to give another example too, of a concentration gradient because these will be really important in cell biology. So here we have a concentration gradient and you can see there's a lot of ions, Every one of these blue things are ions, there's a high amount of ions on this side of the membrane and a low amount on this side of the membrane. And so before we even think about this protein here, just imagine this protein isn't here. If I were to scribble over it, it's not here. If there was no protein to remove that to change the concentration gradient. So if these molecules were just to remain like this with high amounts on this side and low amounts on this side, that would be a example of potential energy. However, when this protein comes into play, so if I remove the squiggles and one of these molecules can actually travel through over to this side. This movement here of this molecule, across this protein, to the other side of the memory is an example of kinetic energy. So, like I said before, membrane concentration is going to be super, super important in cell biology. So that's some examples of energy sources where cells get their energy, for instance, membrane concentration gradients. Um so with that let's move on.

Okay, so now we're gonna talk about energy consumption, which is a big role that cells and organisms play. So um cells must be able to transfer energy from one form to another. And the reason they have to do this is due to the first law of thermodynamics, which states that energy cannot be created or destroyed, however it can be changed and that's what cells do and that's what organisms do. And so there's a few classifications that we use to determine how cells get their energy and how they transfer it. One of them is photo tropes and photo tropes use photosynthesis, which is a term you should be familiar with to change light energy into chemical energy. Now another one is chemo troughs and they change organic nutrients into freely usable energy and this energy can be carbon dioxide, it can be um water. And we see this a lot with ourselves. We're we're technically chemo trophies because we take in food, we organic nutrients um and then we release things like carbon dioxide and water, which can then be used by ourselves or by other organisms as energy sources. Now there's this continual exchange of energy of heat between organisms and the universe in the forms of these atoms and molecules that these are carbon, oxygen, nitrogen, things commonly found on the earth. Um and also water which are also exchanged between organisms and the universe. So there's this constant uptake and release by all of these different organisms. Now, cells when we talk about chemical reactions and energies and cells we use the term metabolism metabolism is this some of chemical reactions in the cell. And it's really made up of two components. And these components are compatible is um which is the breakdown of food into smaller molecules. And anabel is um or anabolic which is the synthesis of molecules. So metabolism is breakdown. A novel is um is the synthesis. And so enzymes are proteins that really assists with these breakdowns and synthesis in these chemical reactions that make up cellular metabolism. So this is gonna be a really big overview. But you can see here you have photo troves um These are things like plants, algae, some bacteria and you have chemo tropes over here with animals, fungi, some other bacteria. And you can see that these arrows are just sort of constantly moving around going around in circles because there exchanging organic compounds, oxygen, carbon dioxide, water with each other and also with the environment. So there's this constant energy source, There's these all of these different reactions and metabolisms happening that allow this cyclic energy transfer between organisms and also between the universe. So one really important energy transfer that we're gonna talk about is actually the movement of electrons. And so they have fancy names which you may remember from your chemistry class. And these are oxidation and reduction. So oxidation is the removal of electrons from an atom or molecule. And it releases energy. So one example of this is the fact that cellular respiration, which we're going to talk about a lot more in future topics um depends on the oxidation of organic molecules. So we're moving the electrons from organic molecules in order to consume and use the energy from food. So oxidation is the removal of electrons, which means that reduction is going to be the addition of electron to an atom or a molecule. And typically this requires some type of energy input. And so um here we have this molecule and I. D. Um and it becomes N A. D. H. Through the addition of electrons. So you can see here reduction is going to be the addition of electrons and this is going to be the removal of electrons and oxidation in the reverse. And this is gonna be a really important molecule that we're going to talk about a lot more in the future. Um But it's just just a general overview of oxidation and reduction so that we understand these principles moving forward. So now let's move on.