Introduction to metabolism: Anabolism and catabolism

what I want to do in this video is talk about the processes that make all life as we know it life as we know it and at its essence we can call this metabolism tabble ism and this is the taking energy in different forms breaking it down into its more fundamental components and then building it up in ways that we would find useful useful for energy useful for structure so that we can actually live our lives we can grow we can reproduce we can respond to our surroundings so as I just said metabolism and we're going to go into a bunch of examples of this metabolism at its heart is really two different processes there's the breaking down of substances for energy or for structure to get back to the building blocks and we call that catabolism catabolism so this is the breaking down of things and then once we've broken down things we're ready to rebuild them in ways that we would find useful and we call this a Nabal ism and Nabal ism or anabolism and a Nabal ism just like that and one way to think about it is imagine that someone had built something with Legos and you want to build something with Legos well you could go to those Legos and you'd want to break it down but not break it down too much you wouldn't melt the plastic you would break it down into the individual LEGO pieces and then you would build it back up into whatever shape that you actually cared about and you might not actually have to even build it break it down all the way to the basic LEGO pieces there might be structures in that first Lego castle that was constructed that you might find useful so let's just think about how all of this gets started and what's excited is what's exciting is that all of this got started or get started from stars from fusion reactions and stars and this right over here is a picture of a star and a star that we are very familiar with this is the Sun but you may or may not realize that the Sun is only one of probably several stars that have been involved in life as we know it the Sun is our most direct source of energy for most of life as we know there's some bacteria and things that are able to live off of vents at the bottom of the ocean because of the heat created but the Sun is our primary source of energy but when I say that other stars might have been involved including dead stars that existed billions of years ago it's because the heavier elements that we're composed of or that are around us in are in the environment the carbon the oxygen we could just keep going pretty much everything other than hydrogen it was constructed in fusion reactions from hydrogen inside of stars so we really may are made up of the remnants of stars and so here we are we're on earth earth was all this condensed matter from four-and-a-half billion years ago probably some nearby supernovae got all of this dust that was constructed in a previous star to coalesce in that way and you have radiation you have energy from the Sun and once again that energy is coming from fusion reactions and it's what's fusing lighter elements into heavier elements so the Sun is also constructing more heavy elements but that energy that energy makes its way to the earth and you have organisms like plants that are able to use that energy to construct the the material the the the food we could say that is eventually going to get around to us and so this process you may or may not be familiar with it this is photosynthesis and we're going to go into a lot more detail since this is and as the word implies photo its photosynthesis it's making things out of light and one thing I like to ask people when they are first exposed to photosynthesis that's like okay we could see this grass growing or we could see this wheat growing and we could see a tree growing but where is that material coming from and the most common answer so somehow it's coming from the ground and there are some new trick nutrients that are coming from the ground but it's really all about fixing carbon and you're going to hear about this a lot especially as we talk about the carbon cycle but you have carbon dioxide primarily in the air so you have carbon you have I'll just write it this way so you have carbon dioxide in the air and what photosynthesis allows these plants to do is take the carbon in that carbon dioxide and form bonds with it turn it from its gas form into solid forms into into glucose molecules and then use that glucose to build up cellulose and to build out other forms of starch and whatever else it might be so it's taking these molecules in the air I'll just draw them as these little is taking these molecules that are in the air and it's using the energy of the Sun to fix them to actually to actually form bonds between the carbons and with other things as we said we're mostly carbon and hydrogen we have some oxygen in there but we're able to form these structures now from there other living organisms and this is a huge oversimplification it can involve bacteria it can involve all sorts of things and just to just to reminder even on that photosynthesis it isn't just light and it isn't just the carbon dioxide it also involves the water and we talked about that so you also have water involved you also have the water involved so you know the carbon dioxide so co2 light from the Sun and water you're able these things are able to grow and nutrients from the earth and then from that you're able to construct things like well you can directly go to these plants that are taking energy from the Sun and and and construct things like bread or you have other animals that will eat things like the grass and then use their and then break them down in their own way and they'll be assisted by bacteria and then rebuild themselves up into a cow into milk and so what this cow is doing its metabolizing this grass it's able to break it down it's able to catabolized the the the various molecules in the grass and break them down into building blocks that can then use to build up the cow to build up milk and whatever else and you might be saying what are these types of molecules that we keep breaking down and then building back up well you have carbohydrates carbohydrates and you're going to see most of the molecules that I'm just I'm about to talk about frankly all of them on the back of nutritional package because it tells you what's inside of it what is your body going to metabolize when it eats that whatever or whatever your on the packet whatever is inside of the package so carbohydrates these are either simple sugars like glucose or fructose or it could be it could be polymers of the sugars polysaccharides it could be a starches made up of many many elements of the or many many multiples of these simple sugars we could be talking about lipids lipids so fatty acids we could be talking about cholesterol these are essential structures and they're also essential for all various metabolic pathways inside of all of life or it could be proteins it could be proteins made up of amino acids sometimes people say the reason why you want the proteins is because it's made up of these amino acids so you could break down these proteins and get the amino acids and then build it up into new proteins proteins and amino acids and all of these things they are found in things like in the foods in the foods we eat which we will then consume we will then metabolize we will first catabolized them and break them down and then we will use those building blocks to build it back up and at the end of the day these are these provide the structures that make our bodies what they are they allow us to interact with our environment and they provide energy and that energy at the end of the day with the true molecular currency for that energy is a molecule called ATP that's a molecule of ATP right over there adenosine triphosphate and the key for ATP why it is the molecular currency for energy are the three phosphate groups so it has these three phosphate groups and we have a whole we have a whole video on it or a whole series of videos on it really but the the main key is that there's a lot of energy especially between the I guess on the last phosphate group and this energy in that bond as the phosphate group breaks off it can release it to provide all sorts of life mechanisms including being able to metabolize things so ATP right over here this is the currency of energy in life as we know it and it's actually an interesting molecule because it's essentially it's a piece of if you just were to take if you were to just this section of it right over here it really is it looks like a piece of RNA it looks like you're taking a you have the ribose you have the adenine you have a phosphate group and it can actually be used to construct things like RNA and even DNA beyond just being the molecular currency of energy so it's fun to see how these pieces all fit together how they can be broken up and you see these patterns over and over again in biological systems and these biological systems are really just made up of breaking down and building back up carbohydrates lipids including fatty acids cholesterol other things and proteins / amino acids so this whole thing you know look around you look at your day look at the things you're consuming and you'll see this pattern over and over and over again and it's all a little mind-blowing because at the end of the day the energy is coming from the fusion reaction in stars and all of the heavy elements around you or even the not so heavy elements all of the carbon the oxygen all of the really non-hydrogen elements they've even been made inside of fusion reactions in in print in stars that might have existed billions and billions and billions of years ago so hopefully that makes you feel a little bit more connected to the universe