Democritus was a Greek philosopher who, over 2,000 years ago, predicted atoms and named atoms. The word “atom” means indivisible. And he thought that there were these particles that were the the smallest possible particle in nature and they are what made up everything else. And he called them atoms or atomos, which means indivisible (which now of course we know they’re not). But that’s how long ago the first person thought of that idea.

So what does “organic” mean to all of you?

In this class when we talk about organic what we’re talking about is the original meaning of organic which means carbon-based. So, food molecules, with the exception of water, are carbon-based molecules. Biology is is all carbon based, and that’s what the word organic means.

There are a lot of different ways that we can represent molecules. Molecules are the smallest functional clumps of matter (with some subtle exceptions). Molecules can have areas of attractive charge and these we call polar molecules, where one side is positively charged and one side is negatively charged.

There can be areas where there is no strong attractive charge, and this is non-polar. So some molecules are completely non-polar for the most part. We’ll get into details.

And then there are molecules that have elements of both non-polar parts and polar parts.

I’m going to give you an example of butyric acid of a lot of different ways that we can represent molecules. So, starting with the common name, butyric acid is a fatty acid that was first found in butter which is where the name “but” (pronounced byoot) comes. Many words in science come from either something that where it was first found or the name of a person. So in this case it comes from where it was first identified in butter, and so that’s the common name we still use.

Then the IUPAC is the International Union of Pure and Applied Chemistry, and that’s a body that an important part of what they do is naming things. So they have conventions for naming molecules and in the IUPAC naming convention butyric acid is called butanoic acid. And there are three parts to “butanoic.” The “but” comes from butyric acid, and butyric acid has four carbon atoms in it and so because of that, a molecule with four carbon atoms the the prefix but has come to mean four so “but” means four carbon atoms. The “an” means that part of the molecule (the hydrocarbon tail) is all single bonds between the carbon. And the “oic” in the end means that it’s a caroxyic acid which we’ll talk about a lot.

So we don’t really even need the word acid on the end because since it’s OIC we know it’s an acid. But a chemist who somehow never learned what butanoic acid was could look at this name butanoic acid and know exactly how the molecule looked just from the name of it.

We use ball and stick models. These are really helpful because so here you can see the black balls are the carbon atoms So you can see the four carbon atoms the white ones are hydrogen and the red ones are oxygen And that’s a convention a lot of people follow not always So you may see different colors in in different diagrams but the nice thing about the ball and stick model is it shows every atom and you can see all of the atoms in a really big complicated molecule You know you might not be able to see them all clearly but it shows the structure of the molecule and you can see exactly how everything works The next one is a space filling model So space filling molecule show represents what it might look like in space how it occupies space but you can see it obscures some of the structure and some of the atoms So in some cases where it’s more important that we kind of understand what the molecule looks like in three dimensions We’ll use a space filling molecule but more often you’ll see the ball and stick model Then we have a displayed formula This shows every single atom C for carbon H for hydrogen O for oxygen You see the double bond between carbon and oxygen And then all the rest are single bonds In chemistry we don’t typically use the displayed model so much especially for larger molecules It gets really unwieldy So instead what we especially in organic chemistry we’ll use the skeletal formula This shows all the same information as the ball and stick or the displayed formula but it’s a lot easier You can see it’s a lot simpler and easier to read quickly If there these lines represent carbon atoms So if there’s an end point with nothing else on it that means there’s a carbon atom here Does anyone know how many bonds carbon forms Anyone remember their high school chemistry four So carbon for four bonds So because there’s one bond is here we know there’s three more bonds and we know that those bonds if if it doesn’t say that they’re hydrogen So we know that this is a carbon atom with three hydrogens coming off of it Here’s an every kink in this is another carbon So we’ve got a carbon here There’s already two bonds So how many hydrogens’s are there going to be Two Two Same thing here too In this case we have a double bond with this oxygen and we have a single bond here and a single bond here So there’s not going to be anything else here And then here we have an oxygen atom that is at the end of this line So if there’s something here then there’s not a carbon atom This means it’s this bond is to the oxygen Oxygen forms two bonds So one is here and the other is to this hydrogen I don’t expect you guys to learn to be able to read these easily but it’s helpful just to know what this means and to be able to look at and kind of understand what’s going on We will look at some skeletal formulas in this class and use them And this what’s called the functional group the caroxyic acid we’ll see a lot So if you don’t remember anything else from the organic chemistry part of the class please remember the carboxilic acid and what it looks like because we’re going to see that again and again and again The other thing we’ll see a lot that occurs a lot is an O group which is an alcohol group There are a few things that that you’ll see so many times they’ll hopefully just start to stick So those are all the ways that we represent molecules And now we’re going to kind of take a step back and look at kernel of wheat as a model for all of the different kinds of molecules that are in foods and in biology Wheat has sugars and starches in it Sugars and starches are very closely related as we’ll see Water fiber proteins fats and phospholipids vitamins minerals and volatile compounds odors So we’re going to go through all these one by one In this lecture this is just going to be an overview and then in in subsequent lectures we’ll dive into all of these a lot more deeply and explain them more comprehensively So sugars and starches we’re going to start with the three most common and most important sugars both in food and in biology Glucose fructose and glactose So these are the smallest units that can still be called sugars And because they’re one group this is one sugar group glucose fructose and glactose They’re called monossaccharides Mono meaning one and saccharide meaning sugar Now you can take these single monossaccharides and link them together into larger molecules If you put two glucose together you get moltos Moltos is the sugar that is I’m sure you’ve all heard of malt right So malt maltting is where you take a grain usually barley but it can be any grain and you germinate it So you put in water it just starts to sprout and then at that point they’re typically dried sometimes roasted and then they’re ground into flour And when seeds just first start to germinate they produce a lot of this sugar moltos So malt has a lot of moltos in it Sucrossse which is common table sugar If you buy white sugar at the store that’s sucrossse Is a combination of fructose and glucose And then lactose which is the sugar in milk is a combination of glactose and glucose So what’s the common element in all of these disaccharides

Glucose So glucose is a super super super important sugar in biology and in food Now the next level is starches So starch like in rice bread potatoes any kind of starch that you eat is a combination of two different molecules amalos and amalopectin And both of these molecules are chains of glucose And they when they link together this this particular type of called alpha glucose they form these helyses these spirals And they’re very very long much longer than this little diagram I made chose So that’s amalos And then amalopect pectin is the same thing except that instead of just being a linear single chain it’s a branched chain So you end up with all these branches but this also made just from glucose And different foods have different ratios of amalos and amalopectin that we’ll talk about which gives them different properties But these are all starches and starches made from sugars So monossaccharides disaccharides and starches So we’re going to dive a little bit into a glucose molecule As I mentioned earlier molecules are all constructed from atoms But I need to point out that you can’t trust atoms because they make up

everything So white is hydrogen black is carbon and red is oxygen

So now we’re going to dive into a carbon atom to show how atoms look as we zoom into them So here we have a carbon atom The middle part with the red and the blue balls is the nucleus The red balls are the neutrons They have no charge positive or negative The blue are protons They are positively charged And then the electrons that are around the outside are negatively charged So this is a very simple unrealistic diagram In reality the nucleus is very very very tiny and there’s a lot of space before the first orbital where the two electrons are going and then a lot of space for the next orbital which is in this case is four electrons But this is generally kind of the structure of it So each of these circles that has the electrons is called a shell And the first shell only holds two electrons and then it’s full The next shell can hold eight electrons and then it’s full And the third shell for all of the atoms that we’re going to be talking about in this class holds eight electrons as well As they get to larger molecules it can hold 18 And it gets really complicated after that But fortunately we don’t have to worry about any of that So for you guys just know the first shell is two the second shell is eight and the third shell is eight So every type of atom has a different number of protons The number of protons in an atom is what defines that atom So for example hydrogen has one proton Carbon has six protons and oxygen has eight protons So if it has eight protons it’s oxygen And then here are all the other ones filling in So helium’s 2 lithium 3 brillium 4 and so forth They may have different numbers of neutrons in them and they may have different number of electrons in them It still doesn’t change the fact that it’s a carbon atom So now we’re going to zoom into hydrogen Hydrogen is very simple It’s one proton just positively charged and one electron which is negatively charged And because this hydrogen atom has a positive charge and a negative charge it’s balanced And so it’s happy in that regard However it’s got one veence electron And how many does the first shell hold Two Two And it wants to have two And it only has one So it’s happy that it has equal charge but it’s unhappy because its outer shell is not full

Now if we look at a hydrogen molecule that is two hydrogen atoms that are sharing their electrons with each other So now we have a molecule that has two protons positively charged two electrons negatively charged So the charge is balanced So it’s happy about that And both of the atoms have two electrons in their outer shell because they’re sharing them So now the outer shells full for both of them And so they’re happy in that regard So this is a very stable happy

molecule When we look at the ball and stick model the sticks in them are this covealent bond The word veilent means power and the outer shell of the atom that has electrons is called the veilent shell So covealent means that it’s the sharing electrons between two different atoms and we represent that with the stick So to summarize sugars and starches they’re made up of monossaccharides such as glucose fructose and galactose glucose being the most important monossaccharide They can be monossaccharides one unit or disaccharides two units And monossaccharides and disaccharides together are what we call simple sugars So if they have any more than that they’re no longer simple sugars Molecules are unique functional clumps of matter made from atoms We have 118 known atoms that we call elements And each one of those has a different number of protons which is what defines it as that atom Some of these are very unstable and are only they’ve been created in a lab but they have very short decay And so they won’t live for very long And there are many that we have never found in nature But these are ones that that either we found in nature or that we’ve created in the lab They’re made from neutrons protons and electrons And remember again neutrons have no charge Protons have a positive charge and electrons have a negative charge They want to have their outer shell full So they will share electrons with other atoms in order to achieve that and still have a balance of positive charge with negative charge And also remember again that the first shell holds two electrons the second one eight and the third one eight Hydrogen has just one proton and one electron And because it wants to have two in its outer shell it will form a bond with another atom to fill its outer shell Hydrogen forms bonds with lots of things And we’ll see hydrogen a lot in organic chemistry Bonding with carbon bonding with oxygen bonding with sulfur all kinds of things All right Now we’re going to move on to water So here is a representation of a water molecule This is a oxygen atom and two hydrogen atoms This little weird squiggly thing is a lowercase delta a Greek letter delta And this letter means a partial charge So an electron is a full negative charge and a proton is a positive charge In this case because they’re sharing electrons this will has a partial positive charge So it’s not completely plus one charge And the oxygen side has a partial negative charge And because this is charged positively here negatively here this is a polar molecule So it can attract other molecules Water is a fascinating and really really important molecule Life as we know it would not be able to exist without water We call it the universal solvent It’s not truly universal but almost everything can dissolve in water to some extent because it’s polar The charge the positive and negative charges on it can pull like for example if you put salt into water Salt is an ion made up of a positively charged molecule or ion actually and a negatively charged ion that stick together because they’re attracted to each other as well So the attraction from water will pull a a an ion of salt off of it And and it’s also because they’re smashing into each other that’s what causes salt to dissolve And the same thing happens with most substances If they’re solids in water the polar nature of water will pull them apart and dissolve them Water lubricates and cushions In biology it has a very high surface tension because again of the polar nature of the molecules So if anyone’s ever done a belly flop you know this from personal experience They’re those little skater bugs that can walk around the surface of water It provides structural support It helps regulate temperature Water has a a very high specific heat which we’ll learn about But what it means is that water can hold a lot of heat much more than most other substances And so because of that is very stable So in our bodies because we have so much water it takes a lot of energy or loss of energy for our temperature to go up and down So it really helps stabilize our homeostasis of temperature It’s also a medium for biological processes So biological processes you know our metabolism and enzymes taking things apart or putting them together or doing other things that they do happen in water It also provides a transportation medium for nutrients and waste So our bud plasma for example and it’s a key element in most biological chemical reactions Water is not only a medium for the reaction but the water molecules themselves are actually really important in how the reactions happen And we will see that in lots of chemical reactions they involve a water molecule becoming part of the reaction that forms or puts together puts together or takes apart other molecules So here’s a water molecule Here’s our glucose molecule We see here all the covealent bonds between them in the spall and stick model If these bonds are between different types of atoms like hydrogen and oxygen because the oxygen has a bigger nucleus with more positive charge in it it’s going to attract the electrons more closely to it And because the electrons are closer to it electrons have a negative charge That means that the oxygen side is going to have a stronger negative charge That’s why we end up with the partial negative charge on the top of the oxygen And the hydrogens’s that aren’t as strong and they can’t they don’t have the electrons around them as often will lose some of that negative charge So it doesn’t fully balance the positive charge from their one proton Here we have the model of oxygen I haven’t drawn all the the protons in here but we’ve got two electrons in our first shell and we’ve got six in our outer shell So it wants two electrons in its outer shell After it fills the first shell which it always fills first it’s going to fill its second shell with electrons with six It can hold eight And so it wants two electrons So hydrogen that has an electron and it’s trying to fill its outer shell as well will share an electron with the oxygen and that fills its shell and it gives it seven to the oxygen and then the second hydrogen does the same thing and it gives now eight to the oxygen and it fills the shell So it’s all electrically balanced and it’s all balanced in terms of everyone’s shell being full So it is stable and happy in this way And this is why water molecules form like this Now there are three different types of ways that electrons are shared in covealent bonds or in in general One is a covealent polar bond So remember polar means that they’re not shared evenly and so there’s going to be a difference in charge on one side versus the other So here is hydrogen and chlorine and so when they bond together the chlorine is going to occupy or you know the electrons are going to be around the chlorine more of the time than they are the hydrogen So same thing like we just saw in water this will have a slight negative charge and this side will have a slight positive charge So it’s covealent because they’re sharing and it’s polar If you have two of the exact same atoms then they have the same pole on the electron So they’re going to share equally So it’s still a covealent molecule but it’s non-polar because they’re even sharing So there’s not going to be a charge on either side And then the last one is rather than a covealent bond it’s an ionic bond And this happens in salts For example sodium chloride is table salt So here we have sodium which has a very weak pull on electrons and we have chlorine which has a very strong pull on electrons So rather than sharing electrons the chlorine actually completely takes the electron from sodium So now sodium has a full positive charge because it’s lost its electron which is negative Chlorine has gained a full electron So it has a full negative charge because it has an extra electron more than the number of protons it has So this is not a molecule These are now two ions but because this is positively charged and this is negatively charged they’re going to stick together It’s it’s not a a magnetic charge but it’s very similar to the way magnetic charge would work with a north pole and a south pole So what holds water together I want you to think about these questions and then we will address them in a couple minutes So why is water a liquid at room temperature but air is

not What causes water to hold together in drops What’s heavier air or water And what causes rain to fall from the sky So the reason for all of these things is hydrogen bonds So we just talked about how the oxygen side of the molecule has a negative charge and the the hydrogen sides both have a slight positive charge and those are going to be electromagnetically attracted to one another So the slight positive here will have a attraction to the negative here This is called a hydrogen bond They’re called hydrogen bonds because this doesn’t have to be oxygen necessarily It could be some other atom But the hydrogen which has a very weak pull will have a positive charge So there’s going to have this attraction here towards each other So again kind of like magnets attracting each other And this hydrogen bond is a super important bond for all kinds of things in chemistry and food and life And this ex accounts for all the things that we just talked about Why is water liquid at room temperature but air is not So air is primarily oxygen which is a non-polar molecule doesn’t have that charge and nitrogen which is also a non-polar molecule which doesn’t have that charge Because those molecules don’t have that attractive charge to each other they don’t stick together very easily So they’re they’re happy on their own Water on the other hand has a very strong charge that attracts them together So they will tend to stick together a lot more easily When they stick together that’s what makes water as opposed to water vapor in the air What causes them to hold together in drops Again the same thing The hydrogen bonds are very strong And you know if you watch a drop of rainfall in slow motion we think of it as a teardrop right But it’s actually a sphere pretty much because they’re very small They have very high surface tension So they’re going to drop in these spheres because all these molecules are sticking together so strongly What’s heavier air water Air is heavier than water actually So you think that water is heavier because you think of water as I mean a bunch of water together But water molecules are actually lighter than air molecules are So that is what allows them to evaporate go up into the atmosphere And then in the atmosphere rain is a little more complicated than this because there need to be nucleation sites for the rain to kind of start the drops But what ultimately happens is two water molecules if they stick together they are now heavier So once enough of them stick together they get heavier and heavier and that’s and then they fall from the sky because then they’re much heavier than the air is So all of this again goes back to hydrogen bonds So I want to talk about state change and chemical change So this is water as an example If we have liquid water and it evaporates or you know it evaporates is called evaporation suffice for us So when it evaporates it’s called evaporation When a gas goes back to a liquid is called condensation When water freezes we call that freezing And when it becomes a solid I guess I should say When it turns from a solid to a liquid we call that melting But there’s another thing that people often don’t think about or don’t know about which is that solids and gases can a solid can go directly to a gas and a gas can go directly to a solid So when it goes from a solid to a gas is called sublimation and when it goes from a gas to a solid is called deposition And we’ll see examples of sublimation So this is state change going from a liquid to a solid to a gas The water molecules are still water molecules There’s not changing the nature of the molecules It’s just changing how closely they’re sticking together and in what way When water becomes a solid it forms a crystal structure And water is the only molecule that does this which is when it becomes a solid because of the way the the crystal structure works it expands slightly So when water is about 4° C that’s the most dense that it becomes and then as it starts to get colder and freeze at 0 degrees it becomes bigger and because of that ice is less dense than water and that’s why ice floats in water Here on the other hand we have chemical reactions So we have on the right hand we have water molecules on the left hand we have hydrogen molecules and oxygen molecules So sometimes when these molecules bang together with enough force and position the right way two oxygen atoms and the four hydrogen atoms the hydrogen atoms might glom onto the oxygen and and break the bonds And so we’ll end up with water molecules rather than hydrogen and oxygen So we have the same number of atoms of each type on each side of the equation but they’re completely different molecules that have different properties from each other So that’s a chemical reaction So in summary water has a lot of functions that make life possible It acts as a medium for biological processes Both the inside and the outside of your cells is mostly water Water helps organisms transport nutrients and waste products It’s a part of a lot of chemical reactions especially in food and biology Water molecules are made from two hydrogen atoms and one oxygen Oxygen has six electrons in its outer shell but it wants eight to fill its shell So it shares electrons with two hydrogen atoms Its outer shell gains those two electrons So it has eight and hydrogen gains one each So it has two filling its outside shell Water molecules are charged molecules So both of the hydrogens’s have partial positive charges and the oxygen side has a partial negative charge So that makes it polar And so because it’s polar it will be attracted to and it will attract any other polar molecule or part of a polar molecule This electromagnetic pull between these molecules creates these bonds that are much weaker than than coalent bonds but they’re much stronger than some other types of bonds that we’ll see And they’re called hydrogen bonds because they involve hydrogen on one of the molecules And matter can be solid liquid or gas And changing the phase does not change the molecule So those are three phases of matter Those are the ones we talk about the most They’re actually five phases of matter Does anyone know what either or both of the other two are plasma is one and the other one is the Bose Einstein condensate which happens at temperatures very close to absolute zero where without I I can’t really explain without getting a lot into physics but things get very weird I’ll just say all right so next we’re going to talk about fiber and we’re going to since we’re talking about wheat we’re going to kind of zoom in to what fiber looks like in wheat If we look at part of the cell wall and we zoom into it we see cellulose Cellulose is made up of microfibbrals that are uh in different directions across each other which gives it a lot of strength If we zoom into the microfiber just one of them then it is made from all of these cellulose molecules which are these very long straight molecules And if we zoom into what those molecules look like they are chains of a type of glucose which is different from it’s glucose like starch is glucose except it’s a beta version of it So there’s a slight change we’ll look at later which changes the way that they link together and makes them straight rather than helix And because of that they can get very close together And because they can get very close together the hydrogen bonds that we just learned about those those electromagnetic bonds bond these very strongly together So that’s what gives cellulose all of its

strength So cellulose pectin pectin is a molecule that’s made out of a different sugar molecule we’ll look at later And other fiber molecules are all found in wheat Cellulose is the most abundant organic polymer on Earth And because it’s made from glucose glucose is the most abundant whether by itself or as a disaccharide or you know with sucrose or with cellulose There are more glucose molecules than any other organic molecule As I just mentioned cellulose forms these very long straight chains and they stick together very strongly and form very strong

fibers Next we’ll talk about proteins Proteins are these long chains of amino acids and I have represented them here with these little like candies Beads on a string is usually what people talk about as a model for what proteins are like So you can think of these as beads that are connected on a string or little candies that are connected on a string So every one of these is an amino acid and there are 20 different amino acids in pretty much in all of nature There are some nuances to that that we’ll talk about later But any plant or animal all the proteins are made from these 20 amino acids in different combinations These are the threelet codes for alanine glycine leucine methionine baline And they also have one letter symbols for all 20 of them And so you can kind of think of it like an alphabet And like an alphabet like in English some of these letters or some of these amino acids occur a lot more commonly than other ones do And these chains proteins can be as few as 50 amino acids long or they can be thousands of amino acids long but it’s still just one long chain In trying to figure out a good analogy for this I came up with this and this was the best I could do on on the drawing of it The way that they chain together is that they have arms kind of that hold onto each other And the left arm is different from the right arm but they’re the same on all of them Their every amino acid’s right arm is the same as every other one And their left arm is the same as every other one And their head unit which is actually hydrogen is the same on all of them as well What’s different is the legs And so here we have uh R and R which is arginine So their their legs are the same And then here we have glycine And their legs are the same as each other And it’s their legs that what determine whether they’re acidic or basic or they have a charge or don’t have a charge There’s a lot of different attributes of the way their legs are that determine the way proteins fold and interact with each other So that’s the basic structure We’ll learn about it in a little more detail but that’s basically how proteins work And proteins can fold and work in different ways So there’s there’s two main types of proteins There’s structural proteins which are fibrous proteins So here I have two little candies wrapped around each other Keratin what your hair and skin and other stuff is made of looks very much like this the two chains of proteins wrapped around each other And then there’s globular proteins which form these balls and globular proteins are functional proteins So they are the proteins in your body that actually do things like enzymes for example are globular proteins Enzymes Enzymes are fascinating super versatile proteins that kind of run everything biology And we’ll see some examples of them They’re really really truly fascinating But they are basically these balls of this one long string of of amino acids And it’s the shape of the protein that determines its function So here we have our periodic table We’re not going to go into this in too much detail or use it too much in the class but I did want to point out a few things First of all different atoms have different electro negativity Electro negativity is how remember I talked about how oxygen will pull the electrons to it a lot more strongly than hydrogen So as we go up to the upper right not talking about helium and the noble gases are a little bit different but like florine they’re more electrogative as we go up to the upper right and less electronegative as we go down to the lower left So if we zoom in on carbon this periodic table is from pable.com which is a free website which if you’re interested is a great site for just tons and tons of information really nicely done It’s a great site for the periodic table So here we have carbon and I just want to kind of point out what all these numbers and stuff mean Number one is the atomic number Hydrogen is one that’s one proton Helium is two two protons Lithium burillium So that’s what’s going to determine remember it’s the number of protons is what determines what type of atom it is Then we have the symbol and often it’s it’s either one or two letters and often it’s going to kind of make sense like C for carbon N for nitrogen There are some cases like PB for lead comes from the Latin So some cases it it may not make a lot of sense but in most cases it’s pretty easy Then we have the common name that we call it and then the atomic weight The atomic weight there’s a term that you might run across called a Dalton You will definitely run across it because I use it sometimes And the atomic weight is based on carbon 12 which is the most common isotope of carbon And carbon 12 has a weight of exactly 12 So that defines everything else So why is this not exactly 12 Anyone know They like average all the other types of carbon like carbon 13 Yeah So they average all the isotopes and there are very few of the other ones but there are some and so the average of them is not going to be exactly 12 and you’ll see that in a lot of places some of sometimes like you know in chlorine is almost 35 and a half So you can see by that that there are two different isotopes there And then the last thing that this periodic table shows is the energy levels So the first shell which is full holds two it has two The second shell which again holds eight has four So just by looking at that number we can determine how many bonds it will typically form Now if we expand this a little bit and we look at hydrogen carbon nitrogen and oxygen hydrogen has one So the first shell holds how many Two So how many bonds will hydrogen form Two One Because it already has one So it will form one bond Carbon has four We’ve already talked about this a lot So how many bonds will form And how many bonds will nitrogen form An oxygen Okay Now I picked these out specifically because these are the four elements that are by far the most common in all life and food So if we look at the percentage of all of these atoms 63% of the atoms in your body are going to be hydrogen almost 10% carbon just a little bit of nitrogen but super important And then about 25% of oxygen So altogether 99.4% of all the atoms are one of these four Other important ones are sulfur We’ll talk about sulfur a lot So one reason that sulfur is so important is because it forms a particular type of bond that’s really important in proteins called a dulfide bond Sulfur has two in its first shell full eight in it second shell full six in its third shell Remember again at at this level before we get into the higher ones this third shell will hold eight So sulfur will form how many bonds Two All right All right So in summary proteins are very long chains of amino acids between 50 and thousands 50 is sort of an arbitrary number Sometimes you’ll see 100 in some texts but there can be chains of amino acids that are fewer than 50 but it’s too small for them to function as a protein And so we call them peptides instead A lot of hormones are peptides Some hormones are proteins In the case of hormones we call them all peptides just because it’s easier whether they’re technically proteins or have more than 50 or more than 100 And a lot of hormones are a derivative of a single amino acid So again that’s sort of an arbitrary number but larger than that they’re big enough to actually function the way a protein does which we’ll talk about what those functions are Our bodies and not just our bodies but in all of nature there are 20 different amino acids Each one has different properties and it’s the forces between the amino acids that cause the proteins to fold into a particular shape And it’s the shape of those proteins and the forces of the the charges on some of the amino acids in the protein that determine the way that the protein functions Over 99% of atoms in food are hydrogen oxygen carbon and nitrogen carbohydrates and fat So sugars starches cellulose pectin don’t contain any nitrogen But nitrogen is a super important part of proteins And we’ll talk about this both in our proteins lecture and in our nutrition lecture because it’s only in proteins in our diets That is why we need to eat protein to create other proteins Your body can make fats out of carbohydrates or vice versa It can burn Glucose is the most important sugar that our body uses as fuel But it can use other sugars It can use fat It can use proteins as fuel But it can’t create nitrogen without nitrogen And it can’t create proteins from the other food molecules And then sulfur is also important component of proteins and is found in two of the 20 amino acids Cysteine being the one we’ll we’ll talk about the most Next is fats and oils So fats are built from long hydrocarbon chains that we call fatty acids And these molecules the hydrocarbon part of it are non-polar So they’re not charged like water molecules are So they don’t have that that strong attractive force like water molecules and sugar molecules and salt because they’re non-polar Now I say sort of because they actually have a little bit of charge and that’s really important and we’ll talk about that and how that works But most people consider them completely nonpolar So if we look at the structure of fat then you have three different fatty acids So this carvic acid group in the end is going to bond with part of the glycerol backbone and we have three of them and that’s what makes up a fat Those the three fatty acids can be all the same They can be all different They can be shorter or longer They can be straight or kinkedked or all all different ways But all all fats and oils are fats are going to look like this Phospholipids are very much like fats They have the same glycerol backbone and the glycerol backbone has three places that can attach to other molecules But unlike fats instead of having three fatty acids they only have two And the the last spot that glycerol can bind to instead of binding to a fatty acid binds to a phosphate group So fatty acids are non-polar So they’re not going to be attracted to water sort of and they will be attracted to other fats The phosphate group however is polar So this will be attracted to water And because of this you can use this phospholipid to mix water and oil together And when you use an egg yolk and make salad dressing out of it that’s exactly what’s happening The egg yolk has a lot of these phospholippids in it And so part of this molecule will attach to fat and part of it will attach to the water And that’s what allows it to combine together So this is what we call an emulsifier And it’s also super super important in biology We’ll see that as well So now fat molecules are not polar So why are they liquids and solids at room temperature Why are some liquids and some solids What makes something a solid is how strongly the molecules stick together If they stick together really strongly then it’s going to be a solid If they’re stick together very loosely and they kind of move around then it’s going to be a liquid So fats and what we what we call a fat when we’re talking you know in cooking we mean something that’s solid at room temperature If it’s an oil that means it’s a liquid at room temperature But fats and oils structurally are exactly the same The only difference in them is how sticky they are And the stickiness has to do with two things One is the length of the fatty acid chain The longer it is the stickier the fat’s going to be And the other one is whether that fatty acid chain is straight or kinkedked Remember when we talked about cellulose molecules the reason they stick together so strongly is they’re very straight So long straight fatty acids have a lot of areas that where they can get very close together and have those bonds that that bond them together They’re not hydrogen bonds We’ll learn about the type of bonds in fats but it’s it’s a similar it’s the same electromagnetic force It’s just a very weaker version of it for different reasons So that’s why some are liquids and some are solids Why don’t fats and water mix A term that you’ll hear a lot in food science and in not in food science is hydrophilic and hydrophobic Has anyone heard of these So hydrophilic means hydro means water and philic means loving So hydrophilic are molecules that love water and they cling to water They’re attracted to water Hydrophobic means scared of water And these are molecules that that don’t bond to water like oil for example I don’t like the word hydrophobic because fats are not scared of water but they’re also not repelled by water And there are very few food science textbooks or anything that really explain this correctly What actually happens is not that because fat if you have a single fat molecule in water it will be attracted electromagnetically with the water But what happens is that water molecules have such a strong attractive force to one another they exclude the fat They kind of push it out because they would rather bond together than bond with the fat And that’s why water and fat separate So now we get to talk about Vanderval’s forces This is another term you will see in almost every text or any class or anything you take They’ll talk about Vanderbal’s forces Vanderval’s forces are actually a category of forces that include London dispersion forces Dubai forces and kism forces And when people talk about Vanderval’s forces what they really mean usually is London dispersion forces Lambert what is the length of the comfy iron majorette Uh two foot long Two foot long Uh yes You have to remember of course to multiply everything Mr Lambert says by three Uh it’s nothing he can help you understand But apart from that he’s perfectly all right I see I’m sorry But it does mean that when he says a bed is 2 foot wide it is in fact 60 ft wide But because everyone uses this term I’m going to go ahead and use this term in this class but just know that it’s not really technically correct For example hydrogen bonds that we just learned about with water are by some definitions a type of Vanderval’s forces They they’re much stronger than typical Vanderval’s forces Some scientists will categorize them separately but they are technically a type of Vanderval’s force as well So non-polar molecules and so these are fatty acids that we’re looking at This is a space filling model of the fatty acids that we just talked about They are attracted to each other through these very very weak forces called Vandervol forces And we learned about how in a water molecule they’re sharing electrons And because the oxygen is pulling on those electrons so much more strongly they are they’re not in orbit We’ll talk about this more but they are surrounding the the nucleus of the oxygen atom part of the water molecule more than they are around the hydrogen And because they’re negatively charged that gives the oxygen as a partial negative charge Here because of the way hydrocarbons work they don’t have that polar nature It all kind of balances out So there’s not this charge But if you were to slow down time super super slow imagine electron and we’re going back to the model where we imagine electrons orbiting like a moon orbits the planet which again is not what really happens but just pretend for now that it does So let’s say there’s a electron orbiting here and when it is orbit is closer to the carbon atom here then there’s going to be the negative charge from the electron here which because there’s a proton here with positive charge that will give this for a very very very brief portion of time a slight positive charge and so because of that there are these very small transient fleeting forces that happen And so there’s a very small charge that that occurs that attracts these together And if there’s a very small positive charge here that’s going to attract the electrons here a little bit more And so they’ll end up being attracted to each other So that very very weak force is what we call Vanderval’s forces And that is super important in how a lot of molecules but fats in particular what we’re talking about now that’s what causes them to stick together So anyone see the movie Bugs Life Remember the scene with the all the ants and the grasshoppers So it’s same kind of thing here They’re very very weak forces but there’s a lot of them So they add up and they make a little stronger force They’re still pretty weak but it’s strong enough to do a lot of interesting things because they operate at a very close range If these molecules can get close enough to each other the closer they are to a point the stronger the forces will be If these molecules are very straight that means that they can get very close to each other So here we have steeric acid It’s this very straight molecule And because it’s very straight and they can get very close together steeric gas melts at 157 degrees Fahrenheit which is pretty hot right That’s hot enough that if you put your hand in water that you would be very uncomfortable and you would burn your hand Now oleic acid which is the exact same So this is 18 carbons Oleic acid also has 18 carbons Everything about it is the same as steeric acid except that there’s a kink in it And because of that they can’t get as close together So oleic acid melts at 55 Fahrenheit which is pretty cold right So this is what determines the the length of this fatty acid and how close they can get together is what determines how sticky they are So next thing I want to talk about is redox reactions Redux is short for reduction oxidation It’s very important in organic chemistry and in biology and health and nutrition but it’s confusing to a lot of people So I want to just try to explain it simply so you sort of understand what’s going on Oxidation means the loss of an electron It’s called oxidation because often involves oxygen Oxygen is very electromagnetically strong and so it can steal an electron from someone else So if I’m oxygen and you got an electron and I steal it from you then you have been oxidized All right Reduction is the opposite thing Reduction is the gain of electron The name is a little confusing because of how it was named historically which we won’t go into but the way I like to think about it is that it’s the charge is reduced So if I’m oxygen again and I’ve stolen electron from you you’ve been oxidized but I’ve been reduced because electron is negatively charged right So I now have a you know my charge has been reduced by one because I’ve added a negative charge to myself Does that make sense So that’s oxidation and reduction And if you forget an acronym that you can use and there’s some other ones you’ll find out there Leo says so So Leo the lion leo loss of electrons is oxidation and GR gain of electrons is reduction There’s also oil rig that sometimes people use You can also just remember what I told you and then you don’t have to worry about the acronyms Redux reactions always happen together So if I steal an electron from you I’m being reduced and you’re being oxidized It always happens at the same time because you know someone is is the recipient of the electron Oxidation is something that we have to worry a lot about in foods and in biology Oxidation of molecules usually wrecks them So oxidation is usually a bad thing Lipid oxidation lipid is a category of molecules that includes fats and phospholipids and there’s lots of other types of lipids we’ll talk about So flour whole whole grain flour like whole wheat flour nuts which have a lot of fat in them cocoa butter which is all fat regular you know cow butter and lots of other animal fats cooking oils and stuff the fats in them can get can and do get oxidized And so this is called rancidity If we say something’s gone rancid then we are specifically talking about the fats in it the lipids in it And it’s oxidative rancidity It’s the fatty acids have been oxid oxidized There’s a different types of different type of ransidity that we’ll talk about later but this is the the more important and more common one that you’ll hear about Red meat can also become oxidized That’s the myoglobin is the the protein that makes red meat look red And so when when red meat is oxidized it turns brown And it will also if you’ve ever smelled rancid fat right It smells bad it tastes bad and it’s going to be bad for you to eat as well So we want to stay away from that and take care of our oils and our fats Same thing with red meat If there’s a lot of oxidation on it it’s not going to taste as good And it’s it could have if you eat a lot of it well eating a lot of red meat has all kinds of health ramifications but oxidized molecules generally are going to be bad There is enzyatic browning So here we have a picture of an apple where part of it has browned So apples potatoes avocados these all turn brown when they’re exposed to oxygen But this is it’s an oxidation reaction but it’s sped up by a protein called an enzyme We’ll talk a lot about enzymes but enzymes again are proteins that speed up reactions So when you cut an apple you’re exposing the apple to oxygen And there are enzymes in the apple that speed up this browning reaction The pigment in that the brown pigment in apples is a melanin molecule So it’s is very closely related to what’s called umelanin which is the pigment in our skin that makes us brown So it’s a very closely related molecule that’s making these guys brown as well And then the last one is rather than oxidation it’s reduction And there’s a molecule in fish called trimethylamine oxide And it can be reduced to trimethylamine which when you have fish that’s old that kind of smelly fish smell is because of the the reduction And so fish use this molecule especially cold water and deep water fish because it protects them from the cold and it protects them from a really intense pressure of being very deep So if you have a fish that swims in very deep cold water it’s going to have a lot more of this molecule It’s going to be a lot more subject to that fishy smell So these are just a few examples of oxygenation and in one case a reduction reaction in foods And as I mentioned they happen simultaneously since one molecule is oxidized and the other one is reduced We call them redux which is short for reduction oxidation Iron when it rests is also an oxidation reaction So the iron is oxidized It loses its electrons to the oxygen and the oxygen is reduced Here we have some red ox And I wanted to show an example here of salt which we’ve already talked about So when the chlorine atom steals an electron from sodium and becomes chloride now it has its outer shell full Sodium only had one electron in its outer shell So it’s very happy to get rid of it because now its new outer shell you know it’s in an outer shell is now full So that’s why that that happens So here there’s no oxygen involved but this is still an oxidation reduction reaction All right So who’s heard about free radicals So I’m going to talk about free radicals So a radical is an atom or molecule that has one or more unpaired electrons And they can be positively negatively or neutally charged Usually they’re negative or neutally charged And because it has an unpaired electron it wants to fill its outer shell like electrons do And so radicals can steal an electron from another molecule or atom Free radicals are radicals that are very highly reactive and will very strongly and easily steal an electron from another molecule

So because as I mentioned earlier when a molecule gets an electron stolen from it it changes the molecule and usually in a bad way And so for us for our health if we eat things that have free radicals in them it’s going to damage molecules in our body which will damage our cells In some cases it can make us sick in in lots of different ways So that’s what a free radical is Now an antioxidant is a molecule that’s very stable that can donate an extra electron to a free radical without becoming unstable itself That’s why we eat foods with antioxidants because we always have free radicals No matter how well we try to eat there’s always free radicals in our body So by eating antioxidants as well it’s going to allow these free radicals to get its its unpaired electron filled in without damaging any of the molecules that that will get damaged by that reaction Hydroxil is a very common and very nasty radical that occurs a lot in in nature and in our diets especially with certain foods that you might eat or cooking methods So that’s an example This is what used to be a water molecule but it’s missing a hydrogen and it’s become oxidized So it’s not only lost the electron but it’s also lost a hydrogen which sometimes happens in an oxidation reaction It may it may be more than just the electron that gets pulled off So in summary fats are three fatty acids that are connected to a glycerol backbone Fats are not water soluble So they will clump together away from water And the longer and straighter the chains are the more sticky they’re going to be That stickiness is caused by Vanderval’s forces Phospholipids are identical to fats except that instead of three fatty acids it’s two And the last sort of slot on the glycerol backbone has a phosphate group on it which is a polar part of the molecule So that can attract water and then the fatty acids can attract other fats and we use that for an emulsifier for all kinds of stuff in in food and cooking to allow fats and water things that are what we call emissible or unmixable to be able to mix together nicely Redux reactions are reactions where electron is stolen from a molecule by another molecule The molecule that takes the electron is reduced because it’s taken a negatively charged electron and reduced and charged The one that loses the electron is oxidized Oxidation reactions change molecules It can change their color their smell their taste and their function Iron turns red for example when it oxidizes And fats who get oxidized become what we call rancid and they smell and taste bad And then last free radicals are molecules that have a very strong need for an electron And because they have that very strong affinity for it they can cause these chain reactions that not only damages one molecule but that molecule now turns into a free radical and it will damage another molecule which will turn to free radical which will damage another molecule And it can go on and on and damage lots of molecules just from one free radical So now what are vitamins We can’t make them Oh this vitamin D Okay that’s a very good answer And vitamin D is also a very astute reception So yes vitamins are molecules that we need that our body needs to function properly that we can’t synthesize ourselves or at least in the required amounts Vitamin D is produced in our skin but not in amounts needed for our health And vitamin D is also interesting because it’s a hormone as well So there are 13 human vitamins All different animals are going to have their own vitamins not necessarily the same as humans And a lot of these vitamins are actually groups of different molecules So like vitamin E for example there’s two major kind of classes of vitamins that make up vitamin E and there’s different examples of them Some vitamins are very specific It’s just one particular molecule But the thing with vitamins is if you are missing a vitamin you will have a very specific disease that will you will get because your body doesn’t have that vitamin that it needs for some purpose Here’s an example of raisin bran and one of the ingredients is mixed tocopererals You’ll see that a lot The reason that they use the tocopererals which is one of the the two groups of vitamins of molecules in vitamin E is because it’s an

antioxidant Another group of substances that our body needs are minerals and there are a lot of minerals that our body needs So here’s an example of iron This is a pferin ring which is I know it means nothing to you but it’s a structure that is common in nature in different ways it’s used and it’s what’s called a prosthetic group which is part when you have a protein sometimes it will attach on another molecule to it to help it function in a particular way This is a prosthetic group for hemoglobin to oxygen This is how oxygen is carried through your body So it’s kind of a complicated set of things that happens but without the iron your body wouldn’t be able to transport oxygen Here is the same molecule another pfin ring but in this case instead of iron it’s magnesium And this magnesium in this same pfin ring is how plants convert sunlight to energy Here we have phosphorus which is a key part of the phosphate group in a phospholipid that we talked about earlier Here we have this is called a zinc finger which is part of a larger molecule These are fairly common structures So zinc again is another mineral that’s part of it So there’s lots of minerals Here’s a list of them We’re not going to go through these right now or ever but just a list of all these different minerals and what they do for our body and why we need them So in some vitamins or molecules that we need to for our metabolism to function properly that we have to get from our diet Other plants and animals can synthesize those molecules and we can’t So we eat those plants to get those molecules instead The reason that this happens they may be molecules that we once in our history in our evolution were able to synthesize but it’s very metabolically expensive for our bodies to create these molecules And if we’re getting them in our foods anyway then why should our body spend all this energy and all these enzymes and everything else that it needs to make to to be able to make these when we’re getting it And so we lose the ability to make these But now because we can’t make them anymore if you have a diet where you’re not getting these because you’re eating you know highly processed foods and things that may not have these vitamins that we need you will get sick because your body needs these molecules to do particular functions So there are 13 human vitamins Four of them are fat soluble AD E and K and all the B vitamins and C are water soluble vitamins Minerals like iron are also essential for our body to carry out particular functions Next we’re going to talk about volatile compounds So volatile means that they’re small molecules that can escape into the air easily So aromomas are volatile molecules that can escape from the food and get into our nose which is how we detect them with these receptors in our nose And if they can’t escape from food we can’t smell them right There are thousands of molecules that give foods all their complex aromomas which is part of flavor This is just a few that I grabbed and put here Vaneline and benzelahhide and so forth that have particular components So like vanoline is the main component of the smell of vanilla Vanilla is much more complex than that There’s actually a lot of different molecules that that make up its smell in real vanilla If you buy artificial vanilla which is what most processed foods are made from you’ll probably only be getting vanoline and nothing else When you cook foods and your house smells wonderful because you have all these wonderful smells those are smells that are no longer in the food right So if you cook foods for a very long amount of time depending on what it is it might be less flavorful because you all of the volatile molecules have already evaporated So when you eat them they’re no longer in the food to become volatile as you’re chewing them and get into your your nose and your smell receptors So we’ve talked a little bit about attractions today about bonds There are four major electromagnetic forces between food molecules Covealent bonds First one we learned that this is when atoms share electrons and it’s a very strong bond It’s the strongest of all the bonds ionic bonds This is when one atom completely steals an electron from another atom Like in the case of table salt the chloride ion has an extra a full extra electron so it’s has a full negative charge And the sodium ion has lost a full electron so it has a full positive charge And those are pretty strong So they’re full charges So there is a pretty strong attractive force Not nearly as strong as coalent bonds but much stronger than a lot of other forces Next is hydrogen bonds This is from the the partial electromagnetic charges like on a water molecule where they’re sharing electrons between two atoms and one of them has a stronger nucleus a stronger positive charge So the electrons are attracted to it more of the time So it will give that stronger atom a slight negative charge and the atoms like hydrogen that don’t have as strong of an attractive force in their nucleus a slight positive charge and then Vanderpol’s forces which are the weakest forces of all of them and these are these very very weak transient forces that happen with molecules that are what we call non-polar So they don’t have these hydrogen bonds that they form but they still have a very weak form of the same type of electromagnetic bond It’s the same electromagnetic bond in ionic bonds These are just stronger a little weaker and much weaker These forces determine either in part or in whole the shape of the molecules It’s the shape and the forces in a molecule that determine its function And because of these shapes and these electromagnetic interactions that’s how molecules interact with each other and do stuff It’s because of those forces within some molecules like proteins which are very long chains have a lot of these forces going on even within the its own molecule and then between molecules That’s how like enzymes can put together or take apart other molecules because of these strong attractive forces So this is super important this the shape and the forces in the molecule that determines its function especially when we talk about proteins So this this are kind of relative bond strengths just so you can can idea coalent ones are very very strong Ionic bonds are you much weaker but still pretty strong relatively than hydrogen bonds are a lot weaker The van der Waals forces or blended dispersion forces are so weak that you don’t even see the line on the chart that I made.