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Main content
Current time:0:00Total duration:8:37
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Video transcript

I want to talk a little bit about carbon and how it cycles through our biosphere and we touch on this in other videos but when we talk about elements like carbon they don't just appear and disappear all of a sudden our biosphere for the most part they have been here since the beginning but they just get recycled from one form to another and that is also true of carbon and to appreciate carbons importance in our biosphere and especially to life I have some some important molecules or examples of important molecules that involve carbon and all of these the carbon are the carbons are these dark gray colors so this right over here this this molecule this is glucose glucose simple sugars it's it's where we can derive a lot of our energy from this is ATP you could view it as a more immediate store of energy in biological systems this right over here is is one of many amino acids the amino acids make up our proteins this right over here is DNA and in all of these you can see the role that carbons playing in fact sometimes the carbon is hard to see because it's closer to the center of these molecules because the carbon for the most part forms a backbone because carbons is really neat this really neat element this really neat atom that can make four bonds so can make these really really really cool structures but the question is how does carbon cycle through our biosphere and we can get as simple or as complex as we want to when we discuss this but on very very simple terms and this is how my brain tends to think about the carbon cycle you can imagine the carbon in our atmosphere that's mainly in the form of molecular carbon dioxide so this right over here this is co2 once again the carbon is in the middle of there bonded to the two oxygens and as much as we talk about co2 and as important as carbon is to living systems in fact our bodies are eighteen to nineteen percent percent carbon carbon by mass so it's very important for biological illogical systems as a as carbon is two biological systems and the role carbon dioxide plays and things like global warming it actually makes them makes up a very small percentage of our atmosphere it's only about 0.04 percent of the gas in our atmosphere most of our atmosphere is actually nitrogen 78% you don't talk a lot about it and oxygen 21% and then a bunch of other a bunch of other elements and molecules but the very simple version of the carbon cycle is okay you have this atmospheric carbon dioxide molecular carbon dioxide hanging out in the air and you have autotrophs like plants so let's say this is the ground and I have a growing plant so that's a plant right over there that's its leaf that's another leaf and the way that plants grow is they're able to take light energy so that's energy coming in from the Sun and use that energy to fix carbon now fixing carbon sounds like a very fancy thing but it's literally taking that that molecular carbon dioxide out of the air and fixing the carbon from it to form to form these different molecules in the plant that help the plant they give the plants structure that give the plant energy and so that that mass of that plant I'm actually in this this room I'm in there's a house plant right next to me it's not just growing out of I mean I guess you could say it's growing out of thin air but the mass isn't just magically appearing it's taking that mass out of the air and so that's where so that's what allows this plant to keep growing and so once again as I said some of that will be in the form of proteins amino acids it could form structural components could there could be fats and also some of it is energy and you could imagine other animals that can't do this that can't photosynthesize well they might want to eat these plants for that energy in other videos we talked about the food cycle and so you know this could be me this could be me having a salad and I might want to eat that plant I might want to eat the plant for the sugar in it and maybe it's an apple of some kind and then that gives my body the energy to live and and as I as I metabolize that glucose so for example glucose is one of the molecules that that plant can form by taking that carbon out of the air and then I might eat might metabolize that glucose from that plant I just ate and as I do that I will release carbon dioxide so I will release the co2 back in the air and then you can see that you can form a cycle here the co2 gets released by things that are metabolizing these organic molecules and then it can get fixed again by autotrophs which are able to store the energy from the Sun within in terms of these bonds by fixing this carbon but there's other pathways that we can have to have these cycles for example some of the co2 it could be absorbed into the ocean it could be absorbed into into the ocean and the ocean it can form carbonate and so once again you still see the carbon right over there carbon bonded to three oxygens and calcium carbonate is a key constituent in things like c s-- and like things like seashells and over time as the seashells break down and get ground up and they get impacted with pressure and over they can form they can form limestone so this right over here is limestone lime stone but once again it fought it it was formed from carbon dioxide being absorbed in the ocean living living things using that calcium using the calcium carbonate the carbonated in conjunction with calcium in order to form these shells which gets ground down and it actually forms these Rock structures you can have situations you can have situations where living things whether we're talking about the autotrophs like plan so we're talking about things like me that are eating the plants that well once they die and there's all this organic matter that hasn't been broken down yet well it gets buried in the ground I'll do the plant because it's less morbid than showing me dead and then so let's say this is the plant well with enough pressure and time sometimes in the dica in the decomposing process some of the carbon might be released but over time this might be compressed and be turned into fossil fuels so when you when you see oil or when you are burning gasoline which is really just a refined part of the oil it is really this organic matter that was that storing energy that plants were able to store from light energy possibly millions or tens of millions of years ago but then if you were to take that same if you were to take that fossil fuel out of the ground which we now do very actively into in order to power all of the things that we need to power and you were to burn it so let me see if I were to let me just draw an example of that so let's say that you just had if you had a canister of oil I can do the oil in black because you could have you'd have trouble seeing it and if you were to burn it if you were to burn it the process of the process of combustion and this is in general if you're burning anything it doesn't just have to be oil it could be burning a piece of wood you're taking that you're taking that organic matter those carbon carbon bonds and in some ways you could say you're doing the reverse of the photosynthesis process you're breaking it down and in that process you're releasing that carbon as getting released in the form of carbon dioxide carbon dioxide which in theory could then be fixed once again so the general idea autotrophs like plants when they when they photosynthesize they can fix that carbon and then it could either be burnt and with then a combustion process can release that carbon back into the atmosphere or you could have other animals eating that plant and then as they metabolize as they break these carbon carbon bonds to power themselves or to just do whatever they need to do that also can release carbon dioxide
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