Overview of Biochemistry Basics

Good afternoon class. Today we're going to cover Unit 3, Chapter, it's still Chapter 2 actually, Part B, it's actually Part C, but let's call it Part B, it doesn't really matter, but it's still in the second chapter. Chapter 2 is a very big chapter. So in this unit here, it's, we're going to cover biochemistry. Okay, Part two biochemistry so what is biochemistry biochemistry is the study of chemical composition and reactions of living matter all chemicals are either organic or inorganic we've already looked at inorganic compounds namely water salts and many acids and bases from the previous chapter the characteristic of these compounds is that they do not contain carbon whereas organic compounds always contain the elements carbon and hydrogen and generally oxygen as well. Many organic molecules are made up of long chains of carbon atoms linked by cavallan bonds. The carbon atoms typically form additional cavallan bonds with hydrogen or oxygen atoms and less commonly with nitrogen, phosphorus, sulfur, iron or other elements. Examples of organic compounds are carbohydrates, fats, proteins, and nucleic acids. Both inorganic and organic compounds are equally essential for life. Section 2.7, organic compounds. So organic molecules will contain carbon. That's their characteristic. There are exceptions, CO2. And so carbon dioxide and carbon monoxide are not organic, they're inorganic molecules. A unique property of carbon is that it's electroneutral. It is involved in sharing electrons, never gains or loses them. So it's not involved in ionic bonding. It forms four cavillate bonds with other elements. That's what makes it versatile. And carbon is unique to living systems. So, you know, we say that on Earth we have carbon-based life. Life is carbon-based. In this figure, let's look at the four groups of macromolecules or organic molecules. So carbohydrates, those are the large, they're large molecules and they're made up of subunits or monomers called sugar and the functions are they store energy and they can act as a structural material. Examples are the starch found in potatoes or the glycogen that is stored in the liver. Lipids or fats are made up of monomers of fatty acids, generally, not all. They're quite variable. Lipids, we'll see. Their main functions are they store energy, they form the membrane when we look at phospholipids, and also examples are steroids. So fat cells are made up of lipids. Proteins are the large macromolecules and they're made up of monomers or subunits of amino acids. Examples of important proteins are enzymes. They also make up structural material like hair. and skin, the keratin on the outer skin layer, and important peptides. Nucleic acids are the fourth category of large macromolecules. They're made up of subunits or monomers of nucleotides, and their job is to store genetic information. An example would be DNA or RNA. Section 2.7, we're going to look at synthesis. and hydrolysis. So many of these are polymers. You know, the examples I showed you, the carbohydrates, the proteins, the lipids, and the nucleic acids, and they're made up of subunits, chains of similar units or building blocks called the monomers. And these can be synthesized by dehydration reactions or synthesis, and they're broken down by hydrolysis reactions. If you look at the little picture there. So you have the large polymer and it's made up of little subunits called monomers. So if the large polymer were a protein, the little subunits would be the amino acids. So this figure again, it's nice. Repetition is good because there's a lot of terminology in this chapter and there's chemistry and not all students are comfortable with chemistry. So repetition is great. So the polymer. So here we have the four groups of polymers. So let's start with the carbohydrate. So the carbohydrate is the large polymer and it's made up of monomers of monosaccharides. Mono is one, saccharide is sugar. Lipids. are the large polymers and they're made up of monomers of fatty acids. Nucleic acids are the polymers and they're made up of subunits called nucleotides. Proteins are the large polymers and they're made up of subunits called amino acids. So let's look at this figure. In figure A, this is a dehydration synthesis reaction. So you have two subunits and you want to build a larger polymer. So in a dehydration synthesis reaction, as the name suggests, you are removing water and you are building and you're making a covalent bond between those two monomers. And now the molecule got larger. In figure B, it's the opposite. You have a polymer and you want to break it up into its individual molecule. subunits or monomers, you add water. So water and energy, of course, both reactions A and B will require an input of energy. So the water comes in and enzymes, of course, energy and enzymes. So the water will come in, break that bond, that covalent bond, and you will have smaller subunits. So this is hydrolysis. This figure shows So you have these monosaccharides. Let's say you want to join two monosaccharides and the reaction is a dehydration synthesis. So a water molecule is removed and you have a covalent bond that forms and now you have a disaccharide. Disaccharide means two sugars. In the second figure, the bottom one. you have a disaccharide, you add water, and the water is going to break that bond and is going to be part of the two monomer subunits, the two monosaccharides. So the bottom reaction is a hydrolysis, which happens all the time in the process of digestion. Figure 2.14 is the figure from your book, Dehydration Synthesis and Hydrolysis. So in figure A. a dehydration synthesis. Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. And so water is removed and a covalent bond is formed between those two monomers. In figure B, you have two monomers that are linked by covalent bond. You add water. and you separate the two monomers. Figure C shows a reaction of glucose plus fructose to make sucrose. So that's the forward reaction. In the forward reaction, water is released. So that's a dehydration synthesis. In the backward reaction, you are breaking down sucrose into its subunits. glucose, and fructose. And this reaction here is a hydrolysis reaction. Section 2.8, carbohydrates. So carbohydrates include sugars, starches, glycogen. These contain carbon, hydrogen, and oxygen in their formulas. And hydrogen and oxygen are in a two-to-one ratio. There are three classes. I added four actually, but there are three main classes. So monosaccharides, it's one single sugar. So the monomers, monosaccharide is basically the smallest unit of a carbohydrate. Disaccharides, di means two, so there are two sugars joined together by covalent bonding. Oligosaccharides is several sugars, whereas polysaccharides are many sugars. Polymers are made up of Monomers of monosaccharides. So polysaccharides are made up of many monomers joined together by covalent bonding. This very simplified figure shows very simple examples, types of carbohydrates. So a monosaccharide, you have there a six-carbon monosaccharide. Disaccharides are two of those monosaccharides joined together. And polysaccharides are many monosaccharides joined together. Let's look at... Details of each one, each one of the carbohydrates. So monosaccharides, these are simple sugars containing three to seven carbon atoms. The general formula is CH2O and N as a subscript, where the N is the number of carbon atoms. So let's say N equals to six, then the formula would be C6H12O6. These, again, are monomers of the carbohydrates. Important monosaccharides are triose sugars. Triose means three carbon sugars. Pentose sugars of noteworthy mention are ribose and deoxyribose. I'll show you those soon. And hexose sugars, very important, glucose, right? I keep mentioning glucose. That's the blood sugar. This figure shows examples of the monosaccharides. We have trioses, pentoses, and hexoses. So let's start on the left there. Glyceraldehyde is an example of a three-carbon sugar. Notice it's got three carbons and it's got oxygens and hydrogens. Then we have the two pentose sugars that are very important because we'll see them again. Ribose, which is found in RNA, ribonucleic acid. And deoxyribose is found in DNA, deoxyribonucleic acid. I wouldn't ask you the difference between the two in terms of structure. Just note that they both have five carbons. Six carbon sugars, mannose, galactose, fructose. Those are other examples of six carbon sugars. We mentioned the glucose as well. figure from your book, figure 215A, examples of monosaccharides. We have glucose, we have fructose, we have galactose. These are exosugars. No, I would not put a picture of galactose on a test and ask you, name this sugar. I would not be able to myself, okay? And and Pentose sugars, as I mentioned, deoxyribose and ribose. These are five carbon sugars. Disaccharides are double sugars. These are too large to pass through cell membranes. The important disaccharides examples are sucrose or table sugar. Maltose or sugar. malt sugar, you may have heard of it found in beer, for example, and lactose. Lactose is milk sugar. And they are formed, again, to remind you by dehydration synthesis of two monosaccharides. So for example, if you take a glucose and a fructose in a dehydration synthesis, in other words, water is removed, you end up with sucrose. So maltose would be two glucose monomers joined together. And we said we find maltose in beer. Sucrose is a glucose and a fructose. Any sugar, anything containing sugar contains sucrose. And lactose is a glucose and a galactose monosaccharide. These two monosaccharides joined together. Figure 2.15b, these are important disaccharides. So we have sucrose, we have maltose, and we have lactose. And again, no, you will not be asked to recognize them, you know, to differentiate between the three. Just recognize that they are disaccharides. Now we're at oligosaccharides. Oligo means... some. So oligosaccharides are polymers that contain a small number of monosaccharides. A very good example of oligosaccharides are those those sugars on the surface of red blood cells, okay, that determine our blood type. Okay, so here, for example, group A people would have group A, they would have a certain oligosaccharide, let's call, you know, type A oligosaccharide. Group B people would have type B oligosaccharide on the surface of the red blood cells. Group AB would have both. type A and type B, and group O do not have either one on the surface of the red blood cells. I know we haven't covered cell membranes yet. Okay, so cell membranes are what, you know, what make up the outer portion of the cell. So if you look at this, this is a Small stretch of a cell membrane, a little piece of a cell membrane. You will notice that on the outside of the cell you have these oligosaccharides, these sugars that are found on the outside. And the job of these is to determine the cell's identity. You know, we have white blood cells, which their job is immunity. They're always patrolling the surface of our cells. They're always checking, and if they don't recognize it, then they will mark. the cell for destruction. Okay, so they're always looking at the surface and they scan the surface. If they recognize the oligosaccharides, then they will leave the cell alone. And now we come to polysaccharides. These are large polymers of monosaccharides and are formed by dehydration synthesis of many monomers. Important polysaccharides are starch and glycogen. Starch is what Plants use to store sugars, to store carbohydrates, whereas animals will store carbohydrates in the form of glycogen, right? We are not potatoes, so we don't store our sugar in the form of starch. We don't make starch. We eat starch for energy, but we store the subunits, the monosaccharides, in the form of glycogen, and they're not very soluble. molecules. Figure 215C shows glycogen. Okay, so that's what glycogen looks like. It's made up of many monomers of glucose. So it's made up of many glucose subunits linked together. And it's branched. It's actually a branched molecule. Section 2.9, lipids. So lipids contain carbon, hydrogen, and oxygen, but less than in carbohydrates, and sometimes they will also contain phosphorus. They are insoluble in water. I'm sure you've noticed that oil in water does not dissolve. The main types are triglycerides, phospholipids, steroids, and eicosanoids. Let's look at triglycerides. These are called fats when solid and oils when liquid. They're composed of three fatty acids which are linear hydrocarbons. Hydrocarbons, it's basically a chain of hydrogens and carbons. And the fatty acids, the three fatty acids are bonded to one glycerol molecule, which is a sugar, a glycerol is a sugar alcohol. by of course dehydration synthesis. The main functions of triglycerides are energy storage, insulation and protection. Figure 216A is an example of a triglyceride. So a triglyceride, well actually this here just shows you one of the fatty acids. So here we have a fatty acid, notice it's got, it's a long chain of carbons and hydrogens also known as hydrocarbon. And if you want to join the fatty acid to a glycerol, the glycerol is the top molecule there. It's got lots of OHs. That's why it's called a sugar alcohol. You remove water, remember dehydration, and then you have a covalent bond that is formed. In figure 2, 16B, we can see a complete... triglyceride molecule, which consists of three fatty acid chains and one glycerol. And there's the three covalent bonds that are formed between the fatty acids and the glycerol molecule. And luckily, you don't have to learn the names of these bonds. But in biology, we have to know that these are ester linkages and the carbohydrates are glycosidic linkages. And in proteins are called peptide bonds, in nucleic acids are called phosphodiester linkages. But here, luckily, we don't have to go into those details. Figure 216C is a simplified drawing of the same triglyceride. Notice that all the carbon hydrogens have been, you know, they're not written in. So you just see the... the kinks in the molecule showing where the carbon hydrogens where the carbons would be found so you have two types of fatty acids the saturated and unsaturated i'm sure you've heard of these terms before so in a saturated fatty acid all the carbons are linked via a single covalent bonds and it's because they are saturated with hydrogens. If they are saturated with hydrogens, there are no double bonds. And as a result, the molecules will be linear. They, and will pack very close together. And that's why they form solid, that's why they are solid at room temperature. So examples of, so you would find saturated fatty acids in animal fats and butter. So I'd room temperature butter is solid and it's because of the linear structure of the fatty acids. So figure 217a shows an example of a saturated fat. So recognize you have the three fatty acids joined to a glycerol and in the fatty acid chain there are no double bonds which means that the that there are lots of hydrogens. I know there's the oxygen there with the double bond, but that one doesn't count. It's actually part of the carboxyl group. Okay, but we don't want to get into those details, but it's not really part of the hydrocarbon chain. In unsaturated fatty acids, one or more carbons in the hydrocarbon chain are linked via... double bonds resulting in reduced hydrogen atoms. So in unsaturated fatty acids there are less hydrogen atoms and because of that the double bonds will cause a kink or a bend in the fatty acid so they cannot pack together closely resulting in unsaturated fatty acids being liquid at room temperature. Examples are plant oils like sunflower oil, olive oil. There's also trans fats and omega-3 fatty acids. So trans fats are modified unsaturated fatty oils that resemble the structure of saturated fats and are considered unhealthy. And that's why Canadians have removed it from a lot of baked goods. They're usually found in baked goods. There are still small amounts, but there's less than the acceptable amount. Whereas omega-3 fatty acids, those are the heart-healthy fatty acids. They're found in fish, for example, fish oils, also flaxseed oil, and those are good, like they're healthy because they lower our levels of cholesterol. Figure 217b. We see examples of unsaturated fats. So in this figure, the two fatty acids are saturated, the first two, but the third one is an example of an unsaturated fatty acid because of the presence of the double bond. And when there's a double bond present, there are less hydrogens, and that's why we say that it's unsaturated. So notice that there's a little bend. in the a little kink in the molecule and so it's not a straight chain as we see with the with the saturated fatty acids. The next group of lipids are the phospholipids. These are modified triglycerides because You have two fatty acids that are covalently bonded to a glycerol, and the glycerol is bonded to a phosphorus-containing group. The head and tail regions have different properties. The head is polar and hydrophilic. Hydrophilic means attracted to water, whereas the tails are nonpolar and hydrophobic, which means that they are repelled. by water. And phospholipids make up cell membrane structure. Okay, so we're going to look at pictures to help understand these characteristics. In figure 218A and B, we have examples of phospholipid structure. So figure A, notice there's the glycerol group, the two fatty acids, one of them is saturated. right the one on the left the other the second one is unsaturated because of the kink in the molecule the little bend and uh and then we have a phosphate group uh phosphate nitrogen containing group um whereas the figure uh figure b will give you this it's this chemical structure of a phospholipid so now you can recognize the fatty the two fatty acids the glycerol group and the um phosphate containing group. Now let's look at this in a little bit more detail. So the glycerol and the phosphate nitrogen containing group is considered hydrophilic water loving because without getting into a lot of details, but the phosphate group has four oxygens. It's not phosphorous. There's a phosphorus, yes, but there's also four oxygens and that makes it hydrophilic. Whereas the non-polar tails oh yes you can see it on the right there the phosphorus yes with the four oxygens okay whereas the fatty acid portion is the non-polar portion because it contains lots of carbons and hydrogens and we said that those are non-polar they're hydrophobic and water fearing so the phospholipid has It has this, it's called amphipathic behavior because it's got both a polar region in the molecule and a nonpolar region of the molecule. Figure 218C shows a schematic diagram of a phospholipid. That's how it's usually represented. When you see a circle with two... tails. Okay, so the circle would be the polar head, in other words, the glycerol plus the phosphate, the phosphate group, whereas the non-polar tails would be the fatty acids, the hydrophobic portion. And when you have a bunch of them together, they will orient themselves spontaneously into a bilayer, two layers. of phospholipids. They will do that spontaneously. So if you have a bunch of phospholipids and throw them in water, that's exactly how they are going to place themselves. The hydrophilic heads towards the water, whereas the hydrophobic tails away from the water. Steroids is the third group of lipids. These consist of four fused or interlocking ring structures. The most important steroid is cholesterol. It's made by the liver, but it also is found in our food when we eat animal products. So you find it in cheese and eggs and in meat. It's very important for the synthesis of vitamin D, also other steroid hormones like testosterone and estrogen and progesterone, and for the synthesis of bile salts. Remember bile? that we talked about that is made by the liver. And it's also important in the cell plasma membrane structure. It's one of the components of the cell membrane. I know I showed you the oligosaccharides, but steroids are also embedded in the membrane. Figure 219 shows you a generalized steroid structure. So notice the four fused rings or four interlocking hydrocarbon rings. So steroid is made up of mostly carbons and hydrogens. So different steroids have different groups attached to the four ring backbone. And this particular steroid is cholesterol. This figure shows different examples of steroids. And again, no, you will not be asked to recognize any one of them. Just maybe to recognize the general structure. So we have cortisol and corticosterone. These are our stress hormones. Aldosterone, we'll learn its important function next semester. It is... related to blood pressure. Progesterone and estradiol, those are female hormones, and testosterone is a male hormone. Eicosanoids are lipids derived from arachidonic acid, which is a fatty acid that must be absorbed in the diet because it cannot be synthesized by the body. There are two major classes of eicosanoids, the prostaglandins and the leukotrienes, but we're only going to look at prostaglandins because virtually all tissues synthesize and respond to them. So prostaglandins play a role in blood clotting, control of blood pressure, inflammation and labor contractions. So for example, prostaglandins are released by damaged tissues. They stimulate nerve endings and produce the sensation of pain. Another example in terms of labor contractions, prostaglandins are released in the uterus and help trigger the start of the labor contractions. Inflammatory actions are blocked by NSAIDs, non-steroidal anti-inflammatory drugs such as aspirin or ibuprofen. Now we're at the section 210, proteins, the third group of macromolecules. We've looked at carbohydrates, we've looked at lipids, the different groups of lipids. So proteins make up 20 to 30% of cell mass, have the most varied functions of any molecules that we've talked about. They can play a role in structure, chemical role as in enzymes. and also contraction movement. They contain the carbon, the hydrogen, oxygen. They also contain nitrogen and sometimes sulfur and phosphorus. Remember, they're polymers made up of subunits or monomers of amino acids, and they're held together by peptide bonds. And the shape and function is due to their four levels, four structural levels. 220 A, B, and C give some examples of protein functions. So under the category of structural proteins, so here the function is mechanical support. An example is collagen. It's found in all connective tissue. It's the single most abundant protein in the body. It is responsible for the tensile strength of bones, tendons, and ligaments. B shows under the category of enzyme proteins. So the function of these proteins are catalysis, where the protein enzymes speed up chemical reactions. So they are essential for virtually every biochemical reaction in the body. For every biochemical reaction, you need an enzyme or else it would happen very slowly. An example here is this enzyme that breaks down a disaccharide into its individual monosaccharides. The other category of protein functions is transport proteins. So these move substances, for example, in blood or across plasma membranes. A good example is hemoglobin. Hemoglobin is a transport protein. protein that transports oxygen in the blood. Some plasma membrane proteins transport substances such as ions across the plasma membrane. 220 D, E, and F under the category of contractile proteins. So their function, these proteins, their function is movement. Two examples are actin and myosin and these cause muscle cell contraction. and function in cell division in all cell types. We're going to see this in your second anatomy and physiology course. Communication proteins. Notice these are embedded in the membrane, in the phospholipid bilayer. So their function is transmitting signals between cells. They can act as chemical messengers, such as hormones or protein hormones, or as receptors in the plasma membrane. So an example is insulin, which is a protein, acts at its receptor to regulate blood sugar levels. And the last category seen here is the defensive proteins. So they protect the body against disease. An example are the antibodies that are released by B cells, they're a component of the immune system, and they bind and inactivate foreign substances. So they can bind bacteria, toxins, or in this case, a virus. So proteins are the large polymers, and they're made up of monomers or subunits of amino acids. There are 20 types of amino acids. and they're joined together by dehydration synthesis. Remember, they form covalent bonds, and these bonds are specifically called peptide bonds. All the amino acids contain, both are made up of an amine group and an acid group, and in fact, they can act as either an acid or a base, and they differ by, and they differ So the 20 amino acids will differ in their R groups. This figure shows a generalized example of an amino acid. So it's made up of a central carbon, an amine group, an acid group, the carboxyl acid there, a hydrogen, and a variable side chain. is shown as R. So all 20 amino acids are similar in that they have the amine group, the hydrogen, the acid group, the central carbon, but they differ in terms of their R. This figure shows examples of essential amino acids. Essential amino acids are amino acids that our body doesn't synthesize, and so we have to... obtain from our diet. So these are 10 essential amino acids. There are 20 amino acids, but I'm just showing you 10 examples. So notice all of them have a central carbon, an amine group, an acid group, the carboxyl group there is called an acid group because it has the ability to lose the hydrogen, and it has the hydrogen, but it has a variable side chain. So The side chain is different in valine and nusine and isoleucine, so the part in red would be the R, represents the R portion of the amino acids. And no, you do not have to memorize the different amino acids. These are just examples of amino acids that are commonly found. This figure shows joining two amino acids together in a dehydration synthesis and formation of a peptide bond. So notice the carboxyl group or the acid group of one amino acid joins the amine group of the other amino acid, a water molecule is removed and a peptide bond is formed. A peptide bond is just an example of a covalent bond. Figure 221 is the figure from your book. So you have two amino acids and dehydration synthesis to form a peptide bond. So now the result is a dipeptide. Whereas if you want to break down that dipeptide, you add water and you end up with two amino acids. And adding water is called, again, hydrolysis. Structure. Structure of proteins, the shape of the proteins will determine the function of the protein. So there are four levels of protein structure. The primary, secondary, tertiary, and quaternary. Primary is simply the sequence of amino acids, just the order. You know, first, let's say leucine, then proline, then isoleucine. You see, so just the sequence. Secondary structure is how these primary amino acids interact with each other. And the result could be either an alpha helix coil that resembles a spring or a beta pleated sheet geometry that looks like an accordion. Tertiary structure is how the secondary structures interact together, giving the protein a three-dimensional shape. And quaternary structure is when you have two or more different polypeptides that interact with each other. This figure shows a very simple way of showing the four levels of protein structure. The primary is just those little beads. Those would be the amino acids, just a sequence of amino acids. Secondary structure, you end up either with an alpha helix or beta pleated sheet. Beta pleated sheets, sometimes in a molecule you would only have alpha helix or you would have beta pleated sheets or in some complex protein molecules, you would have both of them. Tertiary structure is how they interact together, how the secondary structure interacts together. And quaternary structure is when you have more than two polypeptide chains that interact together. So to recap, The primary structure of a protein, as seen in figure 2.22a, is simply the linear sequence of amino acids that are found within a polypeptide chain. Polypeptide simply means a chain made up of amino acids joined together by peptide bonds. Figure 2.22b shows the secondary structure of proteins. And here we see the two, the results of hydrogen bonding. Okay, so I did not mention it before, but hydrogen bonding is responsible for this secondary structure of proteins. So the result can either be an alpha helix or a beta pleated sheet. And so this is all, so the... So this is really stabilized by hydrogen bonds. So there's many of them, we said. One hydrogen bond or interaction is not very strong, but because there's many of them, the result is the secondary structure of proteins. Figure 2.22c illustrates tertiary structure. So tertiary structure is the interaction of alpha helix and beta pleated sheets. So, you know, you can have... a tertiary structure that is exclusively made up of alpha helices, one that is made just of beta sheets, but you can also have in some proteins both alpha helix and beta pleated sheets. This figure shows what's happening to ensure this tertiary structure at the molecular level. So in purple, that's your sequence of amino acids. And the R groups are sticking out. They're just showing the R groups. So in purple, it's basically the backbone. It's the amine. It's the carboxyl group, in other words, the acid, the hydrogen, right? The central carbon. But here, what we see are some of the R groups. So to allow for... Formation of tertiary structure, you can have hydrogen bonding between the two different R groups, where one hydrogen would be attracted to the oxygen of another R group. You could have hydrophobic interactions where all the carbon and hydrogen, let's say you have R groups that are made up of only hydrocarbons, carbon and hydrogens, right? They would be attracted to each other and they would fold the molecule into a tertiary structure. Or you could have something called a disulfide bridge. So one amino acid has a sulfur group, another amino acid has a sulfur group, and they form this disulfide bridge, which is a very strong bond. Or you can have one R group with a positively charged group interacting with another R group possessing a negatively charged R group. And so this would form an ionic bond. And so all of these are responsible for tertiary structure. In this figure, figure D, we're looking at an example of quaternary structure. Please note, not all proteins have quaternary structures. Because if a protein has only one polypeptide chain, then it stops a tertiary structure. As soon as you have two or more polypeptide chains interacting together, Then you have quaternary structure. In this case, and maybe it's not clear, but there are four polypeptide chains that interact together to give your final quaternary structure. So proteins fall into one of two categories based on their shape, fibrous or globular. So fibrous, let's start with fibrous. These are structural proteins. They're strand-like. They're like fibers, as the name suggests. They're water insoluble and they're stable structures. Most of them have tertiary or quaternary structure. And they provide mechanical support and tensile strength. Examples of fibrous proteins are keratin, which is found in our hair and the top skin layer, the top layer of our skin, elastin, collagen, which is the most abundant protein in the body and certain contractile fibers. So the figure on the left is collagen. Notice it's made up of three polypeptide chains and hence it has quaternary structure. And so this is an example of a fibrous protein, whereas the figure on the right is rounder or globular in shape, myoglobin, myoglobin that transports oxygen and muscle. is an example of a globular protein. So as we saw in the figure, globular proteins are functional, well, they're functional, also known as functional proteins. They're compact, they're spherical or round. They're more water soluble and sensitive to environmental changes. They also have tertiary or quaternary structure, and they have a specific functional region known as an act... site that's where the biochemical reaction would occur. Examples would be antibodies which are produced by our immune system, hormones, molecular chaperones that help with folding of other proteins for example, and enzymes. The next section is protein denaturation. In a nutshell, when a protein denatures, it loses its shape and therefore it's going to lose its function. So denaturation is when globular proteins unfold and lose their functional 3D shape. Fibrous proteins are more stable. And so it's much more rare for them to be denatured as opposed to globular proteins. And so for globular proteins, when they unfold, then the active site becomes deactivated. Denaturation can be caused by decreased pH, or in other words, an increase in acidity, or also an increase in temperature. It's usually reversible if normal conditions are restored. However, it can be irreversible if changes are too extreme. So for example, when you cook an egg you cannot uncook it. This figure shows on the left a normal protein that is in its normal tertiary structure. However, if there's a change in the environment where, for example, there's a decrease in the pH or also an increase in pH above a maximum, then the protein is going to unfold or denature and it's not going to be functional anymore. So it doesn't lose its primary structure, but it does lose its tertiary structure. And sometimes this is reversible. So you can, you know, if you restore conditions, the denatured protein will re-nature back to normal. So let's talk about enzymes and their very important role as biological catalysts. So enzymes have this globular structure, and by catalysts we mean that they regulate and increase the speed of chemical reactions without getting used up in the process. So whereas in a chemistry lab you'd have to apply heat to speed up the chemical reaction, To lower the activation energy for that reaction, enzymes act as biological catalysts and do and pretty much achieve the same goal. So they lower the energy needed to initiate a chemical reaction, which leads to an increase in the speed of a reaction and it allows for millions of reactions per minute. This figure shows, the figure on top shows the enzyme, so the globular three-dimensional enzyme, and the active site is where the reaction is going to occur. So a substrate, the right substrate, that matches up with the enzyme is going to interact with the enzyme's active site. The figure at the bottom shows different components of an enzyme. So an enzyme is made up of the Apo enzyme which is the protein portion that's inactive the cofactor Non-protein portion that is the activator and the holo enzyme is all the whole enzyme That is going to it's the active enzyme that is going to Is going to interact with a substrate to produce a product Silsum important characteristics of enzymes. So most functional enzymes are referred to as hollow enzymes, consist of two parts. The apoenzyme is the protein portion. The cofactor is a metal ion, or coenzyme is actually the organic molecule, which often of vitamin, of the B vitamins. Another characteristic of enzyme enzymes is that they're very specific. They only act on a very specific substrate. So for example, lactase is going to act specifically on lactose, or sucrase is going to act on sucrose. The names of enzymes usually end in A-S-E, usually, and are often named for the reaction they catalyze. So hydrolases, these will break down water. Oxidases have to do with sugar. Also, there are exceptions, of course, like pepsin is a protein enzyme that does not end in A-S-E. Enzyme action. So enzymes we mentioned before, will lower the activation energy, which is the energy needed to initiate a chemical reaction. So basically enzymes prime the reaction. Enzymes will allow chemical reactions to proceed quickly at body temperatures. So there are three steps that are involved in enzyme action. The first one, the substrate, will bind to the enzyme's active site and it will form a temporary structure called an enzyme substrate complex. The complex will undergo rearrangement of the substrate, resulting in a final product, which is released from the enzyme. And now the enzyme is going to bind to another substrate, because remember, the enzyme is not used in a reaction. The figure on the left shows a reaction without the enzyme, and the figure on the right shows a reaction. with the enzyme. If you notice, so without the enzyme, if we go back to the figure on the left, the activation energy is that energy hurdle at the beginning that the enzyme would require to bring down. So it's very difficult to get products with a high activation energy, whereas in the presence of an enzyme, the activation energy is less, and so it's easier to go from reactants to products. Figure 2.24 shows the steps in enzyme action. So we have the enzyme and the active site on the enzyme. So the substrate, let's say they're amino acids, will bind to the active site. forming an enzyme substrate complex. Then the complex will undergo a rearrangement, so a bond is formed between the two amino acids, for example, storing absorbed energy. Water is released because, remember, this is a dehydration synthesis reaction, as we learned before, and the product is formed. The product is a dipeptide with a covalent bond between the two amino acids and this covalent bond we said is called the peptide bond and so the product leaves and the enzyme is ready to to participate in another reaction Section 211, nucleic acids, our fourth group of macromolecules. Remember, we looked at the carbohydrates, the lipids, the proteins, and now it's the nucleic acids. These are composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus, and they're the largest molecules in the body. The nucleic acids are the polymers, and they're made up of subunits or monomers called nucleotides. A nucleotide is made up of a nitrogen base, a pentose sugar or a 5-carbon sugar, and a phosphate group. There are two major classes of nucleic acids, deoxyribonucleic acid or DNA, and ribonucleic acid and abbreviated RNA. This figure shows a monomer or subunit of nucleic acids. So this is a nucleotide. Let's start looking at the 5-carbon sugar. Okay, so there's carbon 1. We're not going to get into the details of why. So carbon 1, carbon 2, carbon 3, carbon 4, and carbon 5. So this here is a pentose sugar. It's a sugar, and it has 5 carbons. Carbon 1 is bonded to a nitrogen base, also known as a nitrogenous base. Why nitrogenous? Because it's got lots of nitrogens. And carbon-5 is bonded to a phosphate group. A phosphate group has a central phosphorus and four oxygens. Let's start looking at DNA. So DNA has the instructions for the synthesis of all proteins. So we say that it has the genetic blueprint to make proteins. It's like it has the recipe for proteins. It's a double-stranded helical molecule. That's why it's referred to as a double helix. And it's found within the nucleus of a cell. Nucleotides, we said, contain a deoxyribose sugar because it's DNA, a phosphate group, and one of four nitrogen bases. So... The bases are either the purines or the pyrimidines. The two purines are adenine, or A, guanine, or G, and the pyrimidines are cytosine, or C, and thymine, also referred to as T. So this figure shows the pyrimidines and the purines. So if you notice, purines have one ring, whereas purines... Pyrimidines, sorry, have one ring, whereas purines have two rings. Okay, so we said that cytosine and thymine, these are found in DNA. Uracil is only found in RNA. So it's a pyrimidine, which is found in RNA. More about that soon. Purines are adenine and guanine. And no, you don't have to memorize. I would never put cytosine on a test and ask, name this pyrimidine. I would not do that. Okay, so we said again that DNA holds the genetic blueprint for the synthesis of all proteins. Now, the bonding of nitrogen base from strand to opposite strand is very specific. So it follows a complementary base pairing rule. A always pairs with T and vice versa, and G always pairs with C and vice versa. So figure 2.25a and b shows the structure of DNA. So notice just by quickly looking at it that it's a helix. It's a double helix. The ribbon, the purple ribbon, represents the sugar phosphate backbone, it's called. It's made up of, well, the sugar, the deoxyribose sugar and the phosphate group. And then sticking out there in the different colors are the nitrogenous bases. So if you notice, A pairs with T, for example, there. C with G, A with T. Okay, so that's how it works. And what holds those bases together? Hydrogen bonding. Again, hydrogen bonding ensures the tertiary structure of this. of this molecule, of a large macromolecule. Okay, so now we're going to talk about RNA, another large nucleic acid. So RNA is the link between DNA and protein synthesis. And it's slightly different from DNA because it's single-stranded and it's a linear molecule and is active. mostly outside the nucleus, whereas DNA, we said, is found within the nucleus. Instead of deoxyribose sugar, it has ribose sugar. And instead of the thymine base, nitrogenous base or nitrogen base, it is replaced with uracil. There are three types of RNA that are involved in protein synthesis. Messenger RNA or mRNA, transfer RNA or tRNA and ribosomal RNA also known as rRNA. So let's review the differences between DNA and RNA. So whereas DNA is double-stranded, RNA is generally single-stranded. And what holds those bases together in the DNA molecule? The complementary base pairing. is due to hydrogen bonding between the bases. In DNA, the sugar is, the pentose sugar is deoxyribose, whereas in RNA, the pentose sugar is ribose. The bases in DNA are thymine, cytosine, adenine, and guanine, whereas in RNA, the bases are uracil, cytosine, adenine, and guanine. This animation which is found in your PowerPoint presentation. So it's not going to be an animation here, but I like this picture because it shows you the difference between the DNA molecule and the RNA molecule. So DNA is double-stranded, and that's because of the complementary base pairing, whereas RNA is generally single-stranded and linear. Section 212, ATP. So... ATP is the energy currency of the cell. And we usually refer to ATP as a modified nucleotide. Not nucleic acid, but nucleotide. So the chemical energy released when glucose is broken down is captured in ATP, or adenosine triphosphate. So ATP directly powers chemical reactions in cells. offers immediate usable energy needed by body cells. So the structure of ATP is adenine, adenine containing RNA nucleotide with two additional phosphate groups, with a total of three phosphate groups. Figure 226 shows the structure of ATP. also known as adenosine triphosphate. Okay, so we recognize the adenine, that's why it's called adenosine. It has a ribose sugar, just like RNA, and it has, instead of only one, it has three phosphate groups. So the I-energy phosphate bonds can be hydrolyzed to released energy. That's why it's a high energy molecule. So adenosine is just adenine plus the ribose. Adenosine monophosphate is the adenine, the ribose sugar, and one phosphate group. Adenosine diphosphate is with two phosphate groups. And adenosine triphosphate is with the adenine, the ribose, and three phosphate groups. The terminal phosphate group of ATP can be transferred to other compounds as we saw in rearrangement reactions that can use energy stored in the phosphate bond to do work. So when you lose a phosphate group, ATP is converted to ADP and if ADP loses the second phosphate group, it's going to be converted to AMP. So this reaction shows the hydrolysis of ATP in the forward direction. So if ATP is hydrolyzed, it is going to lose a phosphate group, and now ATP is going to be ADP, or adenosine diphosphate, and energy is going to be given off. If you combine ADP with the phosphate group, plus an input of energy, and water is removed, then you go back to ATP. Figure 2.27 illustrates three examples of cellular work driven by energy from ATP. So in figure A, as transport work, we have here a membrane, and embedded in the membrane is a membrane protein, and it has a phosphate that is attached. So if you attach, sorry, the ATP phosphorylates the transport protein. So what that means is that it adds a... phosphate group to it. It activates it, and now the membrane protein is going to change three-dimensional shape, and it's going to allow solutes to cross the cell membrane. A solute could be something like glucose, or it could be an ion. Glucose or ions cannot pass through the phospholipid bilayer. The only way they get through is through a membrane protein. In figure B, you have a relaxed smooth muscle cell. The ATP is going to phosphorylate the contractile proteins inside the muscle cells so that the cells can contract or shorten and ADP and phosphate are formed. In figure C, chemical work. So ATP is going to phosphorylate or add a phosphorus group to one of the key reactants, providing the energy. to drive the energy absorbing chemical reactions and to form a product. Okay, so that's it folks. That's the end of this chapter. And now there's a video at the end summarizing the, you know, the video talks about the four groups of macromolecules or biomolecules. Uh, okay, have a good afternoon. Bye, see you soon. Go ahead and think for a moment about your very favorite food. What is it? Pizza? Macaroni and cheese? Chicken salad? Sushi? Well, we all have different food preferences, but food is a source of large molecules that are needed for life called biomolecules. There are four major biomolecules that make up all of life, and... This will be the focus of this video. Before we get into details about the four biomolecules, we need to talk about one very important vocabulary word. The word monomer. A monomer is a building block. If I had some large substance, the parts that make up the substance are called monomers. Just like building blocks. We're going to talk a lot about monomers today because we need to understand what the biomolecules are made of. And we need to understand biomolecules because they're building components of life. So let's introduce the four biomolecules now and talk a little bit about their functions. We'll start with carbohydrates, carbs. Well, carbs are something that you've probably heard a lot about when people are talking about diets. You know, they try to go low carb or maybe they want a lot of carbs. Diets always come and go. Pasta and breads are examples of foods heavy in carbohydrates. Carbs are actually a very important source of energy. In fact, that's one big function of carbs. They are a great, fast source of energy. If you were a marathon runner, you might want to eat a lot of carbs the night before a race. Lots of marathon runners do this. It's called pasta loading. They eat a big pasta dinner the night before they go out on their marathon. Now, carbs have a monomer. Again, remember, monomers are building blocks. The monomer for carb is a monosaccharide. I know that's a big mouthful, but monosaccharides make up carbohydrates. Next one up is a diverse group known as lipids. Lipids are better known as fats, and they have two different types of building blocks. One type of building block is called a fatty acid, and the other type is called a glycerol. Now, examples of lipids include butter, oil, and cholesterol. Lipids, though, they have a lot of great functions. You might think, well, that's fat. How good can fat be? Well, it just depends when you put it into context. For example, you know those really adorable seals that you see on calendars? They have this fluffy white hair. They're actually called a harp seal. Well, they only look like that when they're babies. When they get older, they're not quite as cute. In their little baby stage, they actually have a lot of this hair that they're born with that keeps them warm. But over time, they have to develop blubber. It's fat, and it helps keep them warm. Lipids are great for insulating. Also, you might not think about fats as being related to energy, but fats are a great source of long-term energy. They can store energy for a long, long time. Say, for example, you wanted to swim the English Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do that in 7 or 8 hours, but it might take a lot longer than that for the average swimmer. More like 25 hours, and that's a lot of swimming. Well, you would want to make sure that your body has enough lipids, enough stored fat that it can pull upon. Because after you burn off those carbohydrates, remember, carbs are the fast source of energy, you might not have enough energy storage unless you have some lipids on hand. Lipids also make up cell membranes, so they are very important for life because all living things are made of cells. Of course, an excessive amount of lipids could be a bad thing for your health. Remember, it's all about moderation. Okay, next, proteins. Now, when you hear about proteins, a lot of times you might think about power bars. They say they have a lot of protein in them and that they help with muscle building. Well, protein is great for muscle building. Examples of foods that are high in protein include meats and many types of beans. The monomers of protein are amino acids. So sometimes you see these labels that say, this has 20 amino acids in this food. And really, they're just trying to say that it has protein. Because proteins are made of amino acids, so that's just some fancy advertising for you. But in addition to being important for muscle development, protein is also very important for other functions, such as working in the immune system and acting as enzymes. Remember, enzymes are made of proteins, so proteins are important for the body. Now, when we start talking about genes, the DNA genes, not the genes you wear, the DNA codes for proteins that are very important for structure and function in the body. The last biomolecule is known as a nucleic acid. Nucleic acids include DNA and RNA, which we'll get to when we get to genetics. They have a monomer called a nucleotide. That's going to be an easy one for you to remember because nucleotide sounds a lot like nucleic acid. And if considering DNA and RNA, both of these are involved in genetic information for the coding of your traits. They are found in a lot of your food because whenever you eat something that came from something once living, it can still contain the DNA. For example, when you eat a strawberry, you're actually consuming all the cells that make up the DNA. that strawberry. And in the nucleus of all those strawberry cells is DNA. Plants and animals both have DNA. In fact, any type of life must contain nucleic acids to direct the cell's activities. So we just powered through introducing the four biomolecules by providing examples, exploring their monomers, and giving some general functions. One last very important part to mention is the structure of these biomolecules. Understanding the structure can help with predicting their properties and easily being able to identify them. One thing I like to tell students to do is to write the four biomolecules in the same order that we went through. Carbs, lipids, proteins, and nucleic acids. Then remember this mnemonic device that goes with these four biomolecules. Cho, cho, chon, chomp. Instead of Chomp at the end with an M. It's chomp at the end with an N The C stands for carbon, the H stands for hydrogen, the O for oxygen. So carbs, lipids, proteins, and nucleic acids all have that CHO in there. It's just that proteins and nucleic acids also have an N, which is nitrogen. And nucleic acids additionally have a P, which is for phosphorus. So again, CHO, CHO, CHON, CHOMP. the major elements in the four biomolecules. Now, these elements are arranged differently in the four biomolecules. It's important to explore the arrangement of the elements in biomolecules because the structure of that arrangement greatly impacts the biomolecule function. So, to the Google to discover some biomolecule arrangement illustrations. Well, that's it for the Amoeba Sisters, and we remind you to stay curious.

So in this unit here, it's, we're going to cover biochemistry. Okay, Part two biochemistry so what is biochemistry biochemistry is the study of chemical composition and reactions of living matter all chemicals are either organic or inorganic we've already looked at inorganic compounds namely water salts and many acids and bases from the previous chapter the characteristic of these compounds is that they do not contain carbon whereas organic compounds always contain the elements carbon and hydrogen and generally oxygen as well. Many organic molecules are made up of long chains of carbon atoms linked by cavallan bonds. The carbon atoms typically form additional cavallan bonds with hydrogen or oxygen atoms and less commonly with nitrogen, phosphorus, sulfur, iron or other elements.

Examples of organic compounds are carbohydrates, fats, proteins, and nucleic acids. Both inorganic and organic compounds are equally essential for life. Section 2.7, organic compounds. So organic molecules will contain carbon. That's their characteristic.

There are exceptions, CO2. And so carbon dioxide and carbon monoxide are not organic, they're inorganic molecules. A unique property of carbon is that it's electroneutral.

It is involved in sharing electrons, never gains or loses them. So it's not involved in ionic bonding. It forms four cavillate bonds with other elements.

That's what makes it versatile. And carbon is unique to living systems. So, you know, we say that on Earth we have carbon-based life.

Life is carbon-based. In this figure, let's look at the four groups of macromolecules or organic molecules. So carbohydrates, those are the large, they're large molecules and they're made up of subunits or monomers called sugar and the functions are they store energy and they can act as a structural material.

Examples are the starch found in potatoes or the glycogen that is stored in the liver. Lipids or fats are made up of monomers of fatty acids, generally, not all. They're quite variable. Lipids, we'll see. Their main functions are they store energy, they form the membrane when we look at phospholipids, and also examples are steroids.

So fat cells are made up of lipids. Proteins are the large macromolecules and they're made up of monomers or subunits of amino acids. Examples of important proteins are enzymes.

They also make up structural material like hair. and skin, the keratin on the outer skin layer, and important peptides. Nucleic acids are the fourth category of large macromolecules. They're made up of subunits or monomers of nucleotides, and their job is to store genetic information. An example would be DNA or RNA.

Section 2.7, we're going to look at synthesis. and hydrolysis. So many of these are polymers. You know, the examples I showed you, the carbohydrates, the proteins, the lipids, and the nucleic acids, and they're made up of subunits, chains of similar units or building blocks called the monomers. And these can be synthesized by dehydration reactions or synthesis, and they're broken down by hydrolysis reactions.

If you look at the little picture there. So you have the large polymer and it's made up of little subunits called monomers. So if the large polymer were a protein, the little subunits would be the amino acids. So this figure again, it's nice. Repetition is good because there's a lot of terminology in this chapter and there's chemistry and not all students are comfortable with chemistry.

So repetition is great. So the polymer. So here we have the four groups of polymers.

So let's start with the carbohydrate. So the carbohydrate is the large polymer and it's made up of monomers of monosaccharides. Mono is one, saccharide is sugar. Lipids. are the large polymers and they're made up of monomers of fatty acids.

Nucleic acids are the polymers and they're made up of subunits called nucleotides. Proteins are the large polymers and they're made up of subunits called amino acids. So let's look at this figure.

In figure A, this is a dehydration synthesis reaction. So you have two subunits and you want to build a larger polymer. So in a dehydration synthesis reaction, as the name suggests, you are removing water and you are building and you're making a covalent bond between those two monomers. And now the molecule got larger. In figure B, it's the opposite.

You have a polymer and you want to break it up into its individual molecule. subunits or monomers, you add water. So water and energy, of course, both reactions A and B will require an input of energy.

So the water comes in and enzymes, of course, energy and enzymes. So the water will come in, break that bond, that covalent bond, and you will have smaller subunits. So this is hydrolysis. This figure shows So you have these monosaccharides.

Let's say you want to join two monosaccharides and the reaction is a dehydration synthesis. So a water molecule is removed and you have a covalent bond that forms and now you have a disaccharide. Disaccharide means two sugars. In the second figure, the bottom one.

you have a disaccharide, you add water, and the water is going to break that bond and is going to be part of the two monomer subunits, the two monosaccharides. So the bottom reaction is a hydrolysis, which happens all the time in the process of digestion. Figure 2.14 is the figure from your book, Dehydration Synthesis and Hydrolysis. So in figure A.

a dehydration synthesis. Monomers are joined by removal of OH from one monomer and removal of H from the other at the site of bond formation. And so water is removed and a covalent bond is formed between those two monomers.

In figure B, you have two monomers that are linked by covalent bond. You add water. and you separate the two monomers.

Figure C shows a reaction of glucose plus fructose to make sucrose. So that's the forward reaction. In the forward reaction, water is released. So that's a dehydration synthesis. In the backward reaction, you are breaking down sucrose into its subunits.

glucose, and fructose. And this reaction here is a hydrolysis reaction. Section 2.8, carbohydrates. So carbohydrates include sugars, starches, glycogen. These contain carbon, hydrogen, and oxygen in their formulas.

And hydrogen and oxygen are in a two-to-one ratio. There are three classes. I added four actually, but there are three main classes.

So monosaccharides, it's one single sugar. So the monomers, monosaccharide is basically the smallest unit of a carbohydrate. Disaccharides, di means two, so there are two sugars joined together by covalent bonding. Oligosaccharides is several sugars, whereas polysaccharides are many sugars. Polymers are made up of Monomers of monosaccharides.

So polysaccharides are made up of many monomers joined together by covalent bonding. This very simplified figure shows very simple examples, types of carbohydrates. So a monosaccharide, you have there a six-carbon monosaccharide. Disaccharides are two of those monosaccharides joined together.

And polysaccharides are many monosaccharides joined together. Let's look at... Details of each one, each one of the carbohydrates. So monosaccharides, these are simple sugars containing three to seven carbon atoms. The general formula is CH2O and N as a subscript, where the N is the number of carbon atoms.

So let's say N equals to six, then the formula would be C6H12O6. These, again, are monomers of the carbohydrates. Important monosaccharides are triose sugars. Triose means three carbon sugars.

Pentose sugars of noteworthy mention are ribose and deoxyribose. I'll show you those soon. And hexose sugars, very important, glucose, right?

I keep mentioning glucose. That's the blood sugar. This figure shows examples of the monosaccharides. We have trioses, pentoses, and hexoses.

So let's start on the left there. Glyceraldehyde is an example of a three-carbon sugar. Notice it's got three carbons and it's got oxygens and hydrogens.

Then we have the two pentose sugars that are very important because we'll see them again. Ribose, which is found in RNA, ribonucleic acid. And deoxyribose is found in DNA, deoxyribonucleic acid.

I wouldn't ask you the difference between the two in terms of structure. Just note that they both have five carbons. Six carbon sugars, mannose, galactose, fructose.

Those are other examples of six carbon sugars. We mentioned the glucose as well. figure from your book, figure 215A, examples of monosaccharides. We have glucose, we have fructose, we have galactose. These are exosugars.

No, I would not put a picture of galactose on a test and ask you, name this sugar. I would not be able to myself, okay? And and Pentose sugars, as I mentioned, deoxyribose and ribose.

These are five carbon sugars. Disaccharides are double sugars. These are too large to pass through cell membranes.

The important disaccharides examples are sucrose or table sugar. Maltose or sugar. malt sugar, you may have heard of it found in beer, for example, and lactose.

Lactose is milk sugar. And they are formed, again, to remind you by dehydration synthesis of two monosaccharides. So for example, if you take a glucose and a fructose in a dehydration synthesis, in other words, water is removed, you end up with sucrose.

So maltose would be two glucose monomers joined together. And we said we find maltose in beer. Sucrose is a glucose and a fructose.

Any sugar, anything containing sugar contains sucrose. And lactose is a glucose and a galactose monosaccharide. These two monosaccharides joined together. Figure 2.15b, these are important disaccharides.

So we have sucrose, we have maltose, and we have lactose. And again, no, you will not be asked to recognize them, you know, to differentiate between the three. Just recognize that they are disaccharides. Now we're at oligosaccharides.

Oligo means... some. So oligosaccharides are polymers that contain a small number of monosaccharides. A very good example of oligosaccharides are those those sugars on the surface of red blood cells, okay, that determine our blood type.

Okay, so here, for example, group A people would have group A, they would have a certain oligosaccharide, let's call, you know, type A oligosaccharide. Group B people would have type B oligosaccharide on the surface of the red blood cells. Group AB would have both.

type A and type B, and group O do not have either one on the surface of the red blood cells. I know we haven't covered cell membranes yet. Okay, so cell membranes are what, you know, what make up the outer portion of the cell.

So if you look at this, this is a Small stretch of a cell membrane, a little piece of a cell membrane. You will notice that on the outside of the cell you have these oligosaccharides, these sugars that are found on the outside. And the job of these is to determine the cell's identity. You know, we have white blood cells, which their job is immunity.

They're always patrolling the surface of our cells. They're always checking, and if they don't recognize it, then they will mark. the cell for destruction. Okay, so they're always looking at the surface and they scan the surface.

If they recognize the oligosaccharides, then they will leave the cell alone. And now we come to polysaccharides. These are large polymers of monosaccharides and are formed by dehydration synthesis of many monomers. Important polysaccharides are starch and glycogen.

Starch is what Plants use to store sugars, to store carbohydrates, whereas animals will store carbohydrates in the form of glycogen, right? We are not potatoes, so we don't store our sugar in the form of starch. We don't make starch. We eat starch for energy, but we store the subunits, the monosaccharides, in the form of glycogen, and they're not very soluble. molecules.

Figure 215C shows glycogen. Okay, so that's what glycogen looks like. It's made up of many monomers of glucose.

So it's made up of many glucose subunits linked together. And it's branched. It's actually a branched molecule.

Section 2.9, lipids. So lipids contain carbon, hydrogen, and oxygen, but less than in carbohydrates, and sometimes they will also contain phosphorus. They are insoluble in water.

I'm sure you've noticed that oil in water does not dissolve. The main types are triglycerides, phospholipids, steroids, and eicosanoids. Let's look at triglycerides.

These are called fats when solid and oils when liquid. They're composed of three fatty acids which are linear hydrocarbons. Hydrocarbons, it's basically a chain of hydrogens and carbons.

And the fatty acids, the three fatty acids are bonded to one glycerol molecule, which is a sugar, a glycerol is a sugar alcohol. by of course dehydration synthesis. The main functions of triglycerides are energy storage, insulation and protection.

Figure 216A is an example of a triglyceride. So a triglyceride, well actually this here just shows you one of the fatty acids. So here we have a fatty acid, notice it's got, it's a long chain of carbons and hydrogens also known as hydrocarbon. And if you want to join the fatty acid to a glycerol, the glycerol is the top molecule there.

It's got lots of OHs. That's why it's called a sugar alcohol. You remove water, remember dehydration, and then you have a covalent bond that is formed.

In figure 2, 16B, we can see a complete... triglyceride molecule, which consists of three fatty acid chains and one glycerol. And there's the three covalent bonds that are formed between the fatty acids and the glycerol molecule.

And luckily, you don't have to learn the names of these bonds. But in biology, we have to know that these are ester linkages and the carbohydrates are glycosidic linkages. And in proteins are called peptide bonds, in nucleic acids are called phosphodiester linkages.

But here, luckily, we don't have to go into those details. Figure 216C is a simplified drawing of the same triglyceride. Notice that all the carbon hydrogens have been, you know, they're not written in.

So you just see the... the kinks in the molecule showing where the carbon hydrogens where the carbons would be found so you have two types of fatty acids the saturated and unsaturated i'm sure you've heard of these terms before so in a saturated fatty acid all the carbons are linked via a single covalent bonds and it's because they are saturated with hydrogens. If they are saturated with hydrogens, there are no double bonds.

And as a result, the molecules will be linear. They, and will pack very close together. And that's why they form solid, that's why they are solid at room temperature. So examples of, so you would find saturated fatty acids in animal fats and butter.

So I'd room temperature butter is solid and it's because of the linear structure of the fatty acids. So figure 217a shows an example of a saturated fat. So recognize you have the three fatty acids joined to a glycerol and in the fatty acid chain there are no double bonds which means that the that there are lots of hydrogens. I know there's the oxygen there with the double bond, but that one doesn't count. It's actually part of the carboxyl group.

Okay, but we don't want to get into those details, but it's not really part of the hydrocarbon chain. In unsaturated fatty acids, one or more carbons in the hydrocarbon chain are linked via... double bonds resulting in reduced hydrogen atoms. So in unsaturated fatty acids there are less hydrogen atoms and because of that the double bonds will cause a kink or a bend in the fatty acid so they cannot pack together closely resulting in unsaturated fatty acids being liquid at room temperature.

Examples are plant oils like sunflower oil, olive oil. There's also trans fats and omega-3 fatty acids. So trans fats are modified unsaturated fatty oils that resemble the structure of saturated fats and are considered unhealthy.

And that's why Canadians have removed it from a lot of baked goods. They're usually found in baked goods. There are still small amounts, but there's less than the acceptable amount.

Whereas omega-3 fatty acids, those are the heart-healthy fatty acids. They're found in fish, for example, fish oils, also flaxseed oil, and those are good, like they're healthy because they lower our levels of cholesterol. Figure 217b. We see examples of unsaturated fats. So in this figure, the two fatty acids are saturated, the first two, but the third one is an example of an unsaturated fatty acid because of the presence of the double bond.

And when there's a double bond present, there are less hydrogens, and that's why we say that it's unsaturated. So notice that there's a little bend. in the a little kink in the molecule and so it's not a straight chain as we see with the with the saturated fatty acids.

The next group of lipids are the phospholipids. These are modified triglycerides because You have two fatty acids that are covalently bonded to a glycerol, and the glycerol is bonded to a phosphorus-containing group. The head and tail regions have different properties. The head is polar and hydrophilic. Hydrophilic means attracted to water, whereas the tails are nonpolar and hydrophobic, which means that they are repelled.

by water. And phospholipids make up cell membrane structure. Okay, so we're going to look at pictures to help understand these characteristics. In figure 218A and B, we have examples of phospholipid structure. So figure A, notice there's the glycerol group, the two fatty acids, one of them is saturated.

right the one on the left the other the second one is unsaturated because of the kink in the molecule the little bend and uh and then we have a phosphate group uh phosphate nitrogen containing group um whereas the figure uh figure b will give you this it's this chemical structure of a phospholipid so now you can recognize the fatty the two fatty acids the glycerol group and the um phosphate containing group. Now let's look at this in a little bit more detail. So the glycerol and the phosphate nitrogen containing group is considered hydrophilic water loving because without getting into a lot of details, but the phosphate group has four oxygens.

It's not phosphorous. There's a phosphorus, yes, but there's also four oxygens and that makes it hydrophilic. Whereas the non-polar tails oh yes you can see it on the right there the phosphorus yes with the four oxygens okay whereas the fatty acid portion is the non-polar portion because it contains lots of carbons and hydrogens and we said that those are non-polar they're hydrophobic and water fearing so the phospholipid has It has this, it's called amphipathic behavior because it's got both a polar region in the molecule and a nonpolar region of the molecule. Figure 218C shows a schematic diagram of a phospholipid.

That's how it's usually represented. When you see a circle with two... tails. Okay, so the circle would be the polar head, in other words, the glycerol plus the phosphate, the phosphate group, whereas the non-polar tails would be the fatty acids, the hydrophobic portion.

And when you have a bunch of them together, they will orient themselves spontaneously into a bilayer, two layers. of phospholipids. They will do that spontaneously.

So if you have a bunch of phospholipids and throw them in water, that's exactly how they are going to place themselves. The hydrophilic heads towards the water, whereas the hydrophobic tails away from the water. Steroids is the third group of lipids.

These consist of four fused or interlocking ring structures. The most important steroid is cholesterol. It's made by the liver, but it also is found in our food when we eat animal products.

So you find it in cheese and eggs and in meat. It's very important for the synthesis of vitamin D, also other steroid hormones like testosterone and estrogen and progesterone, and for the synthesis of bile salts. Remember bile?

that we talked about that is made by the liver. And it's also important in the cell plasma membrane structure. It's one of the components of the cell membrane.

I know I showed you the oligosaccharides, but steroids are also embedded in the membrane. Figure 219 shows you a generalized steroid structure. So notice the four fused rings or four interlocking hydrocarbon rings. So steroid is made up of mostly carbons and hydrogens.

So different steroids have different groups attached to the four ring backbone. And this particular steroid is cholesterol. This figure shows different examples of steroids. And again, no, you will not be asked to recognize any one of them.

Just maybe to recognize the general structure. So we have cortisol and corticosterone. These are our stress hormones.

Aldosterone, we'll learn its important function next semester. It is... related to blood pressure.

Progesterone and estradiol, those are female hormones, and testosterone is a male hormone. Eicosanoids are lipids derived from arachidonic acid, which is a fatty acid that must be absorbed in the diet because it cannot be synthesized by the body. There are two major classes of eicosanoids, the prostaglandins and the leukotrienes, but we're only going to look at prostaglandins because virtually all tissues synthesize and respond to them. So prostaglandins play a role in blood clotting, control of blood pressure, inflammation and labor contractions.

So for example, prostaglandins are released by damaged tissues. They stimulate nerve endings and produce the sensation of pain. Another example in terms of labor contractions, prostaglandins are released in the uterus and help trigger the start of the labor contractions. Inflammatory actions are blocked by NSAIDs, non-steroidal anti-inflammatory drugs such as aspirin or ibuprofen.

Now we're at the section 210, proteins, the third group of macromolecules. We've looked at carbohydrates, we've looked at lipids, the different groups of lipids. So proteins make up 20 to 30% of cell mass, have the most varied functions of any molecules that we've talked about. They can play a role in structure, chemical role as in enzymes. and also contraction movement.

They contain the carbon, the hydrogen, oxygen. They also contain nitrogen and sometimes sulfur and phosphorus. Remember, they're polymers made up of subunits or monomers of amino acids, and they're held together by peptide bonds.

And the shape and function is due to their four levels, four structural levels. 220 A, B, and C give some examples of protein functions. So under the category of structural proteins, so here the function is mechanical support.

An example is collagen. It's found in all connective tissue. It's the single most abundant protein in the body.

It is responsible for the tensile strength of bones, tendons, and ligaments. B shows under the category of enzyme proteins. So the function of these proteins are catalysis, where the protein enzymes speed up chemical reactions.

So they are essential for virtually every biochemical reaction in the body. For every biochemical reaction, you need an enzyme or else it would happen very slowly. An example here is this enzyme that breaks down a disaccharide into its individual monosaccharides.

The other category of protein functions is transport proteins. So these move substances, for example, in blood or across plasma membranes. A good example is hemoglobin. Hemoglobin is a transport protein.

protein that transports oxygen in the blood. Some plasma membrane proteins transport substances such as ions across the plasma membrane. 220 D, E, and F under the category of contractile proteins.

So their function, these proteins, their function is movement. Two examples are actin and myosin and these cause muscle cell contraction. and function in cell division in all cell types. We're going to see this in your second anatomy and physiology course.

Communication proteins. Notice these are embedded in the membrane, in the phospholipid bilayer. So their function is transmitting signals between cells. They can act as chemical messengers, such as hormones or protein hormones, or as receptors in the plasma membrane.

So an example is insulin, which is a protein, acts at its receptor to regulate blood sugar levels. And the last category seen here is the defensive proteins. So they protect the body against disease. An example are the antibodies that are released by B cells, they're a component of the immune system, and they bind and inactivate foreign substances.

So they can bind bacteria, toxins, or in this case, a virus. So proteins are the large polymers, and they're made up of monomers or subunits of amino acids. There are 20 types of amino acids.

and they're joined together by dehydration synthesis. Remember, they form covalent bonds, and these bonds are specifically called peptide bonds. All the amino acids contain, both are made up of an amine group and an acid group, and in fact, they can act as either an acid or a base, and they differ by, and they differ So the 20 amino acids will differ in their R groups.

This figure shows a generalized example of an amino acid. So it's made up of a central carbon, an amine group, an acid group, the carboxyl acid there, a hydrogen, and a variable side chain. is shown as R.

So all 20 amino acids are similar in that they have the amine group, the hydrogen, the acid group, the central carbon, but they differ in terms of their R. This figure shows examples of essential amino acids. Essential amino acids are amino acids that our body doesn't synthesize, and so we have to... obtain from our diet. So these are 10 essential amino acids.

There are 20 amino acids, but I'm just showing you 10 examples. So notice all of them have a central carbon, an amine group, an acid group, the carboxyl group there is called an acid group because it has the ability to lose the hydrogen, and it has the hydrogen, but it has a variable side chain. So The side chain is different in valine and nusine and isoleucine, so the part in red would be the R, represents the R portion of the amino acids. And no, you do not have to memorize the different amino acids. These are just examples of amino acids that are commonly found.

This figure shows joining two amino acids together in a dehydration synthesis and formation of a peptide bond. So notice the carboxyl group or the acid group of one amino acid joins the amine group of the other amino acid, a water molecule is removed and a peptide bond is formed. A peptide bond is just an example of a covalent bond.

Figure 221 is the figure from your book. So you have two amino acids and dehydration synthesis to form a peptide bond. So now the result is a dipeptide.

Whereas if you want to break down that dipeptide, you add water and you end up with two amino acids. And adding water is called, again, hydrolysis. Structure.

Structure of proteins, the shape of the proteins will determine the function of the protein. So there are four levels of protein structure. The primary, secondary, tertiary, and quaternary.

Primary is simply the sequence of amino acids, just the order. You know, first, let's say leucine, then proline, then isoleucine. You see, so just the sequence. Secondary structure is how these primary amino acids interact with each other. And the result could be either an alpha helix coil that resembles a spring or a beta pleated sheet geometry that looks like an accordion.

Tertiary structure is how the secondary structures interact together, giving the protein a three-dimensional shape. And quaternary structure is when you have two or more different polypeptides that interact with each other. This figure shows a very simple way of showing the four levels of protein structure.

The primary is just those little beads. Those would be the amino acids, just a sequence of amino acids. Secondary structure, you end up either with an alpha helix or beta pleated sheet.

Beta pleated sheets, sometimes in a molecule you would only have alpha helix or you would have beta pleated sheets or in some complex protein molecules, you would have both of them. Tertiary structure is how they interact together, how the secondary structure interacts together. And quaternary structure is when you have more than two polypeptide chains that interact together.

So to recap, The primary structure of a protein, as seen in figure 2.22a, is simply the linear sequence of amino acids that are found within a polypeptide chain. Polypeptide simply means a chain made up of amino acids joined together by peptide bonds. Figure 2.22b shows the secondary structure of proteins.

And here we see the two, the results of hydrogen bonding. Okay, so I did not mention it before, but hydrogen bonding is responsible for this secondary structure of proteins. So the result can either be an alpha helix or a beta pleated sheet. And so this is all, so the... So this is really stabilized by hydrogen bonds.

So there's many of them, we said. One hydrogen bond or interaction is not very strong, but because there's many of them, the result is the secondary structure of proteins. Figure 2.22c illustrates tertiary structure.

So tertiary structure is the interaction of alpha helix and beta pleated sheets. So, you know, you can have... a tertiary structure that is exclusively made up of alpha helices, one that is made just of beta sheets, but you can also have in some proteins both alpha helix and beta pleated sheets.

This figure shows what's happening to ensure this tertiary structure at the molecular level. So in purple, that's your sequence of amino acids. And the R groups are sticking out. They're just showing the R groups.

So in purple, it's basically the backbone. It's the amine. It's the carboxyl group, in other words, the acid, the hydrogen, right? The central carbon. But here, what we see are some of the R groups.

So to allow for... Formation of tertiary structure, you can have hydrogen bonding between the two different R groups, where one hydrogen would be attracted to the oxygen of another R group. You could have hydrophobic interactions where all the carbon and hydrogen, let's say you have R groups that are made up of only hydrocarbons, carbon and hydrogens, right? They would be attracted to each other and they would fold the molecule into a tertiary structure.

Or you could have something called a disulfide bridge. So one amino acid has a sulfur group, another amino acid has a sulfur group, and they form this disulfide bridge, which is a very strong bond. Or you can have one R group with a positively charged group interacting with another R group possessing a negatively charged R group.

And so this would form an ionic bond. And so all of these are responsible for tertiary structure. In this figure, figure D, we're looking at an example of quaternary structure.

Please note, not all proteins have quaternary structures. Because if a protein has only one polypeptide chain, then it stops a tertiary structure. As soon as you have two or more polypeptide chains interacting together, Then you have quaternary structure. In this case, and maybe it's not clear, but there are four polypeptide chains that interact together to give your final quaternary structure.

So proteins fall into one of two categories based on their shape, fibrous or globular. So fibrous, let's start with fibrous. These are structural proteins.

They're strand-like. They're like fibers, as the name suggests. They're water insoluble and they're stable structures. Most of them have tertiary or quaternary structure.

And they provide mechanical support and tensile strength. Examples of fibrous proteins are keratin, which is found in our hair and the top skin layer, the top layer of our skin, elastin, collagen, which is the most abundant protein in the body and certain contractile fibers. So the figure on the left is collagen.

Notice it's made up of three polypeptide chains and hence it has quaternary structure. And so this is an example of a fibrous protein, whereas the figure on the right is rounder or globular in shape, myoglobin, myoglobin that transports oxygen and muscle. is an example of a globular protein. So as we saw in the figure, globular proteins are functional, well, they're functional, also known as functional proteins. They're compact, they're spherical or round.

They're more water soluble and sensitive to environmental changes. They also have tertiary or quaternary structure, and they have a specific functional region known as an act... site that's where the biochemical reaction would occur.

Examples would be antibodies which are produced by our immune system, hormones, molecular chaperones that help with folding of other proteins for example, and enzymes. The next section is protein denaturation. In a nutshell, when a protein denatures, it loses its shape and therefore it's going to lose its function.

So denaturation is when globular proteins unfold and lose their functional 3D shape. Fibrous proteins are more stable. And so it's much more rare for them to be denatured as opposed to globular proteins. And so for globular proteins, when they unfold, then the active site becomes deactivated.

Denaturation can be caused by decreased pH, or in other words, an increase in acidity, or also an increase in temperature. It's usually reversible if normal conditions are restored. However, it can be irreversible if changes are too extreme.

So for example, when you cook an egg you cannot uncook it. This figure shows on the left a normal protein that is in its normal tertiary structure. However, if there's a change in the environment where, for example, there's a decrease in the pH or also an increase in pH above a maximum, then the protein is going to unfold or denature and it's not going to be functional anymore.

So it doesn't lose its primary structure, but it does lose its tertiary structure. And sometimes this is reversible. So you can, you know, if you restore conditions, the denatured protein will re-nature back to normal.

So let's talk about enzymes and their very important role as biological catalysts. So enzymes have this globular structure, and by catalysts we mean that they regulate and increase the speed of chemical reactions without getting used up in the process. So whereas in a chemistry lab you'd have to apply heat to speed up the chemical reaction, To lower the activation energy for that reaction, enzymes act as biological catalysts and do and pretty much achieve the same goal. So they lower the energy needed to initiate a chemical reaction, which leads to an increase in the speed of a reaction and it allows for millions of reactions per minute.

This figure shows, the figure on top shows the enzyme, so the globular three-dimensional enzyme, and the active site is where the reaction is going to occur. So a substrate, the right substrate, that matches up with the enzyme is going to interact with the enzyme's active site. The figure at the bottom shows different components of an enzyme. So an enzyme is made up of the Apo enzyme which is the protein portion that's inactive the cofactor Non-protein portion that is the activator and the holo enzyme is all the whole enzyme That is going to it's the active enzyme that is going to Is going to interact with a substrate to produce a product Silsum important characteristics of enzymes.

So most functional enzymes are referred to as hollow enzymes, consist of two parts. The apoenzyme is the protein portion. The cofactor is a metal ion, or coenzyme is actually the organic molecule, which often of vitamin, of the B vitamins. Another characteristic of enzyme enzymes is that they're very specific. They only act on a very specific substrate.

So for example, lactase is going to act specifically on lactose, or sucrase is going to act on sucrose. The names of enzymes usually end in A-S-E, usually, and are often named for the reaction they catalyze. So hydrolases, these will break down water.

Oxidases have to do with sugar. Also, there are exceptions, of course, like pepsin is a protein enzyme that does not end in A-S-E. Enzyme action.

So enzymes we mentioned before, will lower the activation energy, which is the energy needed to initiate a chemical reaction. So basically enzymes prime the reaction. Enzymes will allow chemical reactions to proceed quickly at body temperatures.

So there are three steps that are involved in enzyme action. The first one, the substrate, will bind to the enzyme's active site and it will form a temporary structure called an enzyme substrate complex. The complex will undergo rearrangement of the substrate, resulting in a final product, which is released from the enzyme. And now the enzyme is going to bind to another substrate, because remember, the enzyme is not used in a reaction. The figure on the left shows a reaction without the enzyme, and the figure on the right shows a reaction.

with the enzyme. If you notice, so without the enzyme, if we go back to the figure on the left, the activation energy is that energy hurdle at the beginning that the enzyme would require to bring down. So it's very difficult to get products with a high activation energy, whereas in the presence of an enzyme, the activation energy is less, and so it's easier to go from reactants to products.

Figure 2.24 shows the steps in enzyme action. So we have the enzyme and the active site on the enzyme. So the substrate, let's say they're amino acids, will bind to the active site. forming an enzyme substrate complex.

Then the complex will undergo a rearrangement, so a bond is formed between the two amino acids, for example, storing absorbed energy. Water is released because, remember, this is a dehydration synthesis reaction, as we learned before, and the product is formed. The product is a dipeptide with a covalent bond between the two amino acids and this covalent bond we said is called the peptide bond and so the product leaves and the enzyme is ready to to participate in another reaction Section 211, nucleic acids, our fourth group of macromolecules. Remember, we looked at the carbohydrates, the lipids, the proteins, and now it's the nucleic acids.

These are composed of carbon, hydrogen, oxygen, nitrogen, and phosphorus, and they're the largest molecules in the body. The nucleic acids are the polymers, and they're made up of subunits or monomers called nucleotides. A nucleotide is made up of a nitrogen base, a pentose sugar or a 5-carbon sugar, and a phosphate group. There are two major classes of nucleic acids, deoxyribonucleic acid or DNA, and ribonucleic acid and abbreviated RNA.

This figure shows a monomer or subunit of nucleic acids. So this is a nucleotide. Let's start looking at the 5-carbon sugar. Okay, so there's carbon 1. We're not going to get into the details of why. So carbon 1, carbon 2, carbon 3, carbon 4, and carbon 5. So this here is a pentose sugar.

It's a sugar, and it has 5 carbons. Carbon 1 is bonded to a nitrogen base, also known as a nitrogenous base. Why nitrogenous?

Because it's got lots of nitrogens. And carbon-5 is bonded to a phosphate group. A phosphate group has a central phosphorus and four oxygens.

Let's start looking at DNA. So DNA has the instructions for the synthesis of all proteins. So we say that it has the genetic blueprint to make proteins. It's like it has the recipe for proteins. It's a double-stranded helical molecule.

That's why it's referred to as a double helix. And it's found within the nucleus of a cell. Nucleotides, we said, contain a deoxyribose sugar because it's DNA, a phosphate group, and one of four nitrogen bases. So...

The bases are either the purines or the pyrimidines. The two purines are adenine, or A, guanine, or G, and the pyrimidines are cytosine, or C, and thymine, also referred to as T. So this figure shows the pyrimidines and the purines. So if you notice, purines have one ring, whereas purines... Pyrimidines, sorry, have one ring, whereas purines have two rings.

Okay, so we said that cytosine and thymine, these are found in DNA. Uracil is only found in RNA. So it's a pyrimidine, which is found in RNA.

More about that soon. Purines are adenine and guanine. And no, you don't have to memorize. I would never put cytosine on a test and ask, name this pyrimidine.

I would not do that. Okay, so we said again that DNA holds the genetic blueprint for the synthesis of all proteins. Now, the bonding of nitrogen base from strand to opposite strand is very specific. So it follows a complementary base pairing rule. A always pairs with T and vice versa, and G always pairs with C and vice versa.

So figure 2.25a and b shows the structure of DNA. So notice just by quickly looking at it that it's a helix. It's a double helix.

The ribbon, the purple ribbon, represents the sugar phosphate backbone, it's called. It's made up of, well, the sugar, the deoxyribose sugar and the phosphate group. And then sticking out there in the different colors are the nitrogenous bases.

So if you notice, A pairs with T, for example, there. C with G, A with T. Okay, so that's how it works. And what holds those bases together?

Hydrogen bonding. Again, hydrogen bonding ensures the tertiary structure of this. of this molecule, of a large macromolecule. Okay, so now we're going to talk about RNA, another large nucleic acid.

So RNA is the link between DNA and protein synthesis. And it's slightly different from DNA because it's single-stranded and it's a linear molecule and is active. mostly outside the nucleus, whereas DNA, we said, is found within the nucleus.

Instead of deoxyribose sugar, it has ribose sugar. And instead of the thymine base, nitrogenous base or nitrogen base, it is replaced with uracil. There are three types of RNA that are involved in protein synthesis. Messenger RNA or mRNA, transfer RNA or tRNA and ribosomal RNA also known as rRNA.

So let's review the differences between DNA and RNA. So whereas DNA is double-stranded, RNA is generally single-stranded. And what holds those bases together in the DNA molecule?

The complementary base pairing. is due to hydrogen bonding between the bases. In DNA, the sugar is, the pentose sugar is deoxyribose, whereas in RNA, the pentose sugar is ribose. The bases in DNA are thymine, cytosine, adenine, and guanine, whereas in RNA, the bases are uracil, cytosine, adenine, and guanine. This animation which is found in your PowerPoint presentation.

So it's not going to be an animation here, but I like this picture because it shows you the difference between the DNA molecule and the RNA molecule. So DNA is double-stranded, and that's because of the complementary base pairing, whereas RNA is generally single-stranded and linear. Section 212, ATP.

So... ATP is the energy currency of the cell. And we usually refer to ATP as a modified nucleotide. Not nucleic acid, but nucleotide.

So the chemical energy released when glucose is broken down is captured in ATP, or adenosine triphosphate. So ATP directly powers chemical reactions in cells. offers immediate usable energy needed by body cells.

So the structure of ATP is adenine, adenine containing RNA nucleotide with two additional phosphate groups, with a total of three phosphate groups. Figure 226 shows the structure of ATP. also known as adenosine triphosphate.

Okay, so we recognize the adenine, that's why it's called adenosine. It has a ribose sugar, just like RNA, and it has, instead of only one, it has three phosphate groups. So the I-energy phosphate bonds can be hydrolyzed to released energy. That's why it's a high energy molecule.

So adenosine is just adenine plus the ribose. Adenosine monophosphate is the adenine, the ribose sugar, and one phosphate group. Adenosine diphosphate is with two phosphate groups.

And adenosine triphosphate is with the adenine, the ribose, and three phosphate groups. The terminal phosphate group of ATP can be transferred to other compounds as we saw in rearrangement reactions that can use energy stored in the phosphate bond to do work. So when you lose a phosphate group, ATP is converted to ADP and if ADP loses the second phosphate group, it's going to be converted to AMP.

So this reaction shows the hydrolysis of ATP in the forward direction. So if ATP is hydrolyzed, it is going to lose a phosphate group, and now ATP is going to be ADP, or adenosine diphosphate, and energy is going to be given off. If you combine ADP with the phosphate group, plus an input of energy, and water is removed, then you go back to ATP. Figure 2.27 illustrates three examples of cellular work driven by energy from ATP.

So in figure A, as transport work, we have here a membrane, and embedded in the membrane is a membrane protein, and it has a phosphate that is attached. So if you attach, sorry, the ATP phosphorylates the transport protein. So what that means is that it adds a...

phosphate group to it. It activates it, and now the membrane protein is going to change three-dimensional shape, and it's going to allow solutes to cross the cell membrane. A solute could be something like glucose, or it could be an ion. Glucose or ions cannot pass through the phospholipid bilayer.

The only way they get through is through a membrane protein. In figure B, you have a relaxed smooth muscle cell. The ATP is going to phosphorylate the contractile proteins inside the muscle cells so that the cells can contract or shorten and ADP and phosphate are formed.

In figure C, chemical work. So ATP is going to phosphorylate or add a phosphorus group to one of the key reactants, providing the energy. to drive the energy absorbing chemical reactions and to form a product.

Okay, so that's it folks. That's the end of this chapter. And now there's a video at the end summarizing the, you know, the video talks about the four groups of macromolecules or biomolecules.

Uh, okay, have a good afternoon. Bye, see you soon. Go ahead and think for a moment about your very favorite food.

What is it? Pizza? Macaroni and cheese? Chicken salad?

Sushi? Well, we all have different food preferences, but food is a source of large molecules that are needed for life called biomolecules. There are four major biomolecules that make up all of life, and... This will be the focus of this video.

Before we get into details about the four biomolecules, we need to talk about one very important vocabulary word. The word monomer. A monomer is a building block.

If I had some large substance, the parts that make up the substance are called monomers. Just like building blocks. We're going to talk a lot about monomers today because we need to understand what the biomolecules are made of. And we need to understand biomolecules because they're building components of life.

So let's introduce the four biomolecules now and talk a little bit about their functions. We'll start with carbohydrates, carbs. Well, carbs are something that you've probably heard a lot about when people are talking about diets.

You know, they try to go low carb or maybe they want a lot of carbs. Diets always come and go. Pasta and breads are examples of foods heavy in carbohydrates. Carbs are actually a very important source of energy. In fact, that's one big function of carbs.

They are a great, fast source of energy. If you were a marathon runner, you might want to eat a lot of carbs the night before a race. Lots of marathon runners do this.

It's called pasta loading. They eat a big pasta dinner the night before they go out on their marathon. Now, carbs have a monomer. Again, remember, monomers are building blocks. The monomer for carb is a monosaccharide.

I know that's a big mouthful, but monosaccharides make up carbohydrates. Next one up is a diverse group known as lipids. Lipids are better known as fats, and they have two different types of building blocks. One type of building block is called a fatty acid, and the other type is called a glycerol.

Now, examples of lipids include butter, oil, and cholesterol. Lipids, though, they have a lot of great functions. You might think, well, that's fat. How good can fat be?

Well, it just depends when you put it into context. For example, you know those really adorable seals that you see on calendars? They have this fluffy white hair.

They're actually called a harp seal. Well, they only look like that when they're babies. When they get older, they're not quite as cute.

In their little baby stage, they actually have a lot of this hair that they're born with that keeps them warm. But over time, they have to develop blubber. It's fat, and it helps keep them warm.

Lipids are great for insulating. Also, you might not think about fats as being related to energy, but fats are a great source of long-term energy. They can store energy for a long, long time.

Say, for example, you wanted to swim the English Channel. That's like 21 miles of swimming. The fastest swimmers might be able to do that in 7 or 8 hours, but it might take a lot longer than that for the average swimmer. More like 25 hours, and that's a lot of swimming. Well, you would want to make sure that your body has enough lipids, enough stored fat that it can pull upon.

Because after you burn off those carbohydrates, remember, carbs are the fast source of energy, you might not have enough energy storage unless you have some lipids on hand. Lipids also make up cell membranes, so they are very important for life because all living things are made of cells. Of course, an excessive amount of lipids could be a bad thing for your health. Remember, it's all about moderation. Okay, next, proteins.

Now, when you hear about proteins, a lot of times you might think about power bars. They say they have a lot of protein in them and that they help with muscle building. Well, protein is great for muscle building.

Examples of foods that are high in protein include meats and many types of beans. The monomers of protein are amino acids. So sometimes you see these labels that say, this has 20 amino acids in this food. And really, they're just trying to say that it has protein. Because proteins are made of amino acids, so that's just some fancy advertising for you.

But in addition to being important for muscle development, protein is also very important for other functions, such as working in the immune system and acting as enzymes. Remember, enzymes are made of proteins, so proteins are important for the body. Now, when we start talking about genes, the DNA genes, not the genes you wear, the DNA codes for proteins that are very important for structure and function in the body.

The last biomolecule is known as a nucleic acid. Nucleic acids include DNA and RNA, which we'll get to when we get to genetics. They have a monomer called a nucleotide.

That's going to be an easy one for you to remember because nucleotide sounds a lot like nucleic acid. And if considering DNA and RNA, both of these are involved in genetic information for the coding of your traits. They are found in a lot of your food because whenever you eat something that came from something once living, it can still contain the DNA.

For example, when you eat a strawberry, you're actually consuming all the cells that make up the DNA. that strawberry. And in the nucleus of all those strawberry cells is DNA. Plants and animals both have DNA. In fact, any type of life must contain nucleic acids to direct the cell's activities.

So we just powered through introducing the four biomolecules by providing examples, exploring their monomers, and giving some general functions. One last very important part to mention is the structure of these biomolecules. Understanding the structure can help with predicting their properties and easily being able to identify them.

One thing I like to tell students to do is to write the four biomolecules in the same order that we went through. Carbs, lipids, proteins, and nucleic acids. Then remember this mnemonic device that goes with these four biomolecules.

Cho, cho, chon, chomp. Instead of Chomp at the end with an M. It's chomp at the end with an N The C stands for carbon, the H stands for hydrogen, the O for oxygen. So carbs, lipids, proteins, and nucleic acids all have that CHO in there. It's just that proteins and nucleic acids also have an N, which is nitrogen.

And nucleic acids additionally have a P, which is for phosphorus. So again, CHO, CHO, CHON, CHOMP. the major elements in the four biomolecules. Now, these elements are arranged differently in the four biomolecules. It's important to explore the arrangement of the elements in biomolecules because the structure of that arrangement greatly impacts the biomolecule function.

So, to the Google to discover some biomolecule arrangement illustrations. Well, that's it for the Amoeba Sisters, and we remind you to stay curious.

Transcript for:Overview of Biochemistry Basics

Transcript for:
Overview of Biochemistry Basics