[Music] Hi everybody, it is your AP biology teacher Mr. Poser. Today we're getting into topic 1.2 and that is on the elements of life. Particularly this element that I have on the screen. It is carbon. All the other molecules that we're talking about this unit besides water feature this element among two others but this one really is the most important one and it is carbon. All Earth life is carbon-based. If aliens were to come from some other place in the universe, they would classify us as carbon-based life forms. Um because all of the molecules that are make us making us up that make up our cells have carbon as the primary element. So our four main groups of biomolelecules that we're going to be uh talking about quite a bit here in the subsequent videos and in this unit all have carbon as the backbone of each of those big molecules, big what we call macroolelecules. Um and here's the thing. Why is carbon the nice backbone for it? Well, because a carbon atom can form four different covealent bonds. All right, so think about it. If you're building with uh I don't know, Legos or connects or something. Those are that's a throwback. Um you take the block that can connect to four different things, right? That's something that you're going to kind of put in the center of whatever you're building. Um so that you can, you know, make a large structure. And carbon lends itself to uh being that central atom because it can bond to four different things. Um and in fact carbon is so important as an element and as an atom that uh a whole branch of chemistry is named after compounds that have carbon atoms connected to carbon atoms. Um that's called organic chemistry. So thus organic molecules are ones that come from a living thing and feature carbon atoms bonded to one another. All right. Okay. And just a side note here, I'm sure um outside of the context of biology or chemistry, you've heard the word organic as in uh food grown at the grocery store. What does it mean if something is organic? Um that essentially means that that whatever that produce was, let's say bananas, those bananas were grown uh without any inorganic compounds. All right? which means that the fertilizers or the pesticides or whatever that were used to grow those bananas did not contain any inorganic compounds, any compounds that did not a come from living things and b have carbon atoms bonded to one another. Um, so all the types of molecules that we're going to be talking about here that are macroolelecules, biological macroolelecules, all feature carbon atoms bonded to one another and are important parts of living things. Um, and here are the three elements that you're going to find in all of them. Carbon being the most important because it serves as the backbone elements of all of them. But carbon, hydrogen, and oxygen are the three most prevalent elements in living things. They are found in all types of biological molecules. You can find these molecules in every single living thing that's ever existed ever. You can find carbohydrates, proteins, lipids, and nucleic acids. This right here, um, this top right, let me get my pen here. Uh this top left this is a carbohydrate that is what we call a monossaccharide. This my friend over here is representing a chain of amino acids which will become a protein. Uh this is a lipid right over here. Um I think it might be a sterile right there. And then this is our good friend. Everybody knows it. Um DNA right? Uh so all four of those different types of molecules feature carbon, hydrogen and oxygen but feature carbon as the main element there. Okay. Let me bring that back up. Okay. And uh so here's the deal. Carbon carbohydrates. All right. They are called carbohydrates because they contain carbon. And then hydrate. What does that sound like to you? Hydrate. Oh, you drink your water, right? You hydrate. Okay. So, a carbohydrate is so named because it has carbon atoms with kind of water molecules attached to it. H and O on them. So, the three primary elements that you're going to find in carbohydrates are carbon, hydrogen, and oxygen. And you're not really going to find any other elements. Uh, so C, H, and O are the three that you're going to be looking for for carbohydrates. In proteins, all right, this gets a little more complicated. You're going to find some carbon, hydrogen, oxygen, but then you're also going to find some nitrogen, all right, in each of those individual amino acids. We're going to look at those later. Um, and we're also going to find some sulfur. Okay, sulfur is used to form a type of bond in proteins that we're going to be looking at. uh later they're called dulfide bridges. Um and so thus the five primary elements that you're going to find in proteins are carbon, hydrogen, oxygen, nitrogen, sulfur, chons, as my freshman and my freshman bio uh class used to put it. Um in lipids, all right, what are lipids? Well, we're going to spend a topic on those in just a minute, but they're important for uh energy storage. They're important for cell membranes. They're important for a whole bunch of stuff. Um they're they're like fats and that kind of thing. Uh the molecules that you can find or excuse me the atoms the elements that you can find in lipids are primarily carbon, hydrogen, oxygen. Um but you can also find phosphorus P on the periodic table in what are called phospholipids and those are going to be the molecules that make up a plasma membrane. We're going to spend a long time talking about plasma membranes um in unit 2. So hopefully you will be very familiar with phospholipids before too long. Um, if you can remember CH Hop, chop for lipids. Um, that might be helpful for you to remember what elements you can find there. Um, and last but not least, nucleic acids. Your DNA and your RNA. Um, this molecule up here is a representation of what's called a nucleotide. And you take a couple, you know, thousands of these, um, and you link them up into two chains and you twist them around one another, and you can get a molecule like DNA. uh the atoms the elements that you're going to find in nucleic acids in in nucleotides as well these smaller what are called monomers are carbohy well carbon hydrogen oxygen nitrogen and phosphorus all right you can find all five of those elements in each one of these nucleotides over here and when you take a bunch of these nucleotides and you make two big chains of them and you twist them up you start to get a nucleic acid so ch h o n p cho chop chomp yeah That's how uh my freshman and uh several years ago used to remember what elements are in each um biomolelecule. And I have them listed there here too. Okay. So here's the here's the recap once again. I'm just going to read through this to make sure we got covered all the points. Molecules found in living things feature carbon, hydrogen, and oxygen. Those are what are called organic molecules. And those are once again um any type of molecule that comes from a living thing and features carbon atoms bound to other carbon atoms. Carbohydrates, proteins, lipids, and nucleic acids are the four main biological molecules that we're going to be studying uh for the rest of this unit. Carbohydrates feature carbon, hydrogen, oxygen. Proteins have carbon, hydrogen, oxygen, nitrogen, sulfur. Lipids have carbon, hydrogen, oxygen, and phosphorus. And nucleic acids have carbon, hydrogen, oxygen, nitrogen, and phosphorus. Um, so that is it for 1.2. We're going to be getting into 1.3 next, which is all going to be about how these biomolecules are built up and broken down.