okay so cell not cell chemistry sorry just chemistry for enter amp part two um we stopped at or just prior to chemical reactions last time and i believe i mentioned before that chemical reactions um chemical reactions when they're occurring this is when bonds are being formed between atoms of an element or between molecules or when they're being broken so we're building things up and we're breaking them down anything changed by the reaction those are called the reactants i'm going to try to draw here and anything formed would be the product so we've used water uh in some of our examples so i'm going to draw here so i'm going to draw a reaction so we've got hydrogen two mole or two atoms of hydrogen here represented by the symbol for hydrogen and the number two and i know my drawing is not super great this isn't quite the same as writing on a marker board so we have again the two atoms of hydrogen and we're going to add to that one atom of oxygen so um on the left side of our arrow here the hydrogen and the oxygen those are the reactants and they react together through a chemical reaction to form our product which is a molecule of water so this is a molecule we talked about molecules and compounds in the previous lecture so we can say this is a molecule of water it would also be a compound because it's made up of two different types of elements so we've got hydrogen and oxygen both okay so reactants and products now the other thing um that we can glean from this well this reaction is proceeding from left to right but that doesn't mean that it can't go on the reverse can go right to left we'll look at some of those a little bit later okay i'm trying to get my slide to the next one sorry so you probably have some similar pictures in your textbook i drew out reactants and products i should have chosen different ones i guess i forgot it's the same as as your book but you have again here's our reactants here's our water now if we were reversing so we're building water molecules but let's say we were going from right to left in this reaction we were taking water and breaking it down into oxygen and hydrogen so then um what the reactants would be would be the water molecules this would flip so if we're breaking water down this would be then the reactants will be proceeding in this direction and then that makes oxygen and hydrogen your products instead so it depends on which direction a reaction is occurring when you're building stuff up or breaking it down um absolutely so you know reactions are reversible and in the body that's happening quite often that we're proceeding um you know we're building things up or we're breaking them down and there's some terminology that goes along with that besides just saying building them up and breaking them down so let's look at that sorry about that get rid of that bar okay so when we're building something uh we're taking uh reactants and making a product out of it and again these letters are just representing um the direction this reaction is occurring they're just letters of the alphabet they are not representing any of the elements from the periodic chart so when you take reactants and make a larger product so a molecule that's called a synthesis reaction so we're forming bonds between molecules or atoms to create a larger more complex structure um so in chemistry you know you call that a synthesis reaction then we take it a step further and we're talking about um biological systems like humans um we call those anabolic reactions or you can the other word is anabolism so the process of an anabolic reaction so anabolism is then the term we use for building larger molecules which is a synthesis reaction then we have the opposite of that is breaking something down so we're taking a larger molecule like i was talking about water earlier we're breaking it down into smaller um you know into its atoms or even just smaller molecules so this reaction here is called the decomposition reaction you're breaking bonds to form a more simpler structure again it could be a macromolecule you're breaking down into small you know to small molecules or it could be a molecule that you're breaking down into atoms so for example and so that's called a decomposition reaction in a biological system we call that a catabolic reaction so these terms should also be in your on chapter two of your textbook so catabolism is breaking down so one way i used to remember catabolism versus anabolism think of a catastrophe catastrophes destroy or break down things right so catabolism is breaking down and then you just remember the other one anabolism is building up um the other thing let's practice a little bit up here these are the reactants forming a larger product here here this is our reactant forming smaller products so again we just follow the arrow reactants are on the left side and um if we're going from left to right and then the products are going to be on the right side another type of reaction when we have a large macromolecule if we break it down and then move pieces around basically so it's called an exchange reaction atoms or molecules trade places so we have to it's really a combination of synthesis and decomposition or anabolism and catabolism so first you break the large macromolecules down and then you move parts around and then you have to form bonds again so we're breaking bonds rebuilding the bonds to make new products so reactants and then here's our products and they're different now a little bit about acids and bases and again anything that we don't cover enough in depth please do ask but of course you're reading your chapter along with taking notes from the lecture so um we have a measurement um of hydrogen ion concentration in the solution and we call that the ph scale so um again you have we're made up mostly of water in the body but our body fluids do have a ph our blood ph is supposed to be around you know constant around 7.45 or we can get really sick or even you know die so the ph scale again it's measuring the concentration of hydrogens in a solution we'll look at that just a little bit more but for every number on the scale you know from 0 to 14 is how the scale runs um for one you know number change that's actually a tenfold change in concentration so when you look at something that drops from you know a page of seven to a ph of six that doesn't seem like a very big drop but in reality it really is um that's a huge concentration change so again uh it may look like it's just one number but and that's why we measure ph out to the decimals typically so again our blood ph has to be around 7.45 and any change from that could make us sick and so it doesn't have to change a lot really okay you probably have a similar picture in your book but this is just showing you on the ph scale here's zero down here and notice it says in pink greater hydrogen ion concentration and this is the acidic end of the ph scale 7 is considered neutral here in the middle and then above 7 all the way up to 14 this is a lower hydrogen ion concentration we call that a basic solution or alkaline solution so it's lower in hydrogen but we're going to see it's higher in hydroxyls so when you see brackets like this around the symbol for an element that is a shorthand or notation that indicates to you concentration so hydrogen ion concentration indicated by the brackets then over here oh negative is hydroxyl and again the brackets indicate that they mean concentration of hydroxyl so they're showing you off to the left here uh in these beakers just a representation of what it means a neutral solution means that you have the same amount of hydrogen ions as you do hydroxyls and if you notice hydrogen and hydroxyls when they react together they make water so that's two hydrogens and oxygen gives you water notice the human blood is right around seven that's 7.45 that i mentioned so right here neutral okay then when we go on the uh acidic end of our scale this means you have more hydrogens in the solution or in our body foots than you do hydroxyls and then up here for basic it's the opposite you have more hydroxyls as i mentioned earlier than you do hydrogens either end of the ph scale for example you see if your oven cleaner household bleach you can see that these chemicals would be detrimental if you accidentally ingested them or if you you know get them in high concentrations on your skin they can have damaging effects so the um very basic in the um very alkaline end of up here of the ph scale can be detrimental for you just like the acidic end now for us um you know battery acids bad right but our stomach acids are pretty strong here too and of course that's self-contained contained within the stomach it's obvious that it's needed to digest or break down bonds of things that we eat so this is why your stomach acids you know why it's acidic and that's why we call it stomach acids because it is very acidic okay and we'll talk more about that so just some examples and what it means to be acidic or basic so any substance that releases ions in water we call those electrolytes so remember from the last lecture that ions are atoms that have gained or lost electrons and now have a charge and when ions have a charge um they react with each other and so opposites attract so ions are called electrolytes so any well substances that release ions when they break down in water so if um you have a substance mixed with water and it's an electrolyte that releases specifically hydrogens those ions released or hydrogens we call that solution then not only is it an electrolyte but it's an acid so all of them are called electrolytes and then depending on what ions are released we take it a step further so if they release hydrogen ions they're called acids if electrolytes release ions that are hydroxyls we call those bases and we saw that in the picture previously other ions that can be released um so other you know electrolytes release any other ions we call those salts so you've got acids bases and salts so like sodium potassium magnesium all of these what they have why they're called electrolytes because they have a charge they conduct electricity absolutely so here's our picture again just a little larger for you to see that again if it's a basic also called an alkaline solution it's going to have more hydroxyls neutral solution equal amounts hydrogens and hydroxyls acidic and you know neutral because again they react and form pure water and then here we have the acidic solution with more hydrogen ions so uh in the human body i mentioned before that um blood needs to be very close to neutral 7.45 and so we are constantly our body systems are working to maintain that through homeostasis we use something called a buffer so chemical buffers are substances that resist ph change so we do have molecules in the body that act as buffers and of course if you're in a chemistry lab you can have substances that are called buffers as well so any chemical whether it's a man-made chemical outside the body or something in your body that you're using anything that resists a big ph change keeps it from you know becoming really acidic or really alkaline or basic is the other word for that those are called buffers so what does a buffer do this chemical accepts hydrogen ions when you have them in excess so if you have a lot of hydrogen ions any molecule that will react with the hydrogens and accept them that's considered a buffer and then the same thing the opposite if you're very basic and you don't have enough hydrogen ions they're going to donate or release hydrogen ions when they're depleted so when a hydrogen becomes part of a larger molecule it's no longer affecting your ph right so because remember ph is a measure of the concentration of hydrogens in the solution so if they're part of a larger molecule for example bicarbonate is one of our electrolytes and it can accept a hydrogen so that would make this h2 co3 and that becomes carbonic acid so bicarbonate is in our body system in all of our fluids absolutely inside our cells and outside of our cells and so if we have excess hydrogen ions bicarbonate's going to bind to those and we're going to talk about this quite a bit more when we get to the respiratory system especially but again bicarbonate acts as a buffer for us it is an electrolyte and they can accept or donate hydrogen ions hemoglobin has a protein so hemoglobin is written as hb um there's the protein and there's a protein in hemoglobin that also acts as a buffer and can also accept hydrogen ions so it binds to the hydrogens so remember that hemoglobin transports oxygen or maybe not remember but hemoglobin does transport oxygen and in the same way they can bind to oxygen it can bind to hydrogens and take them out of solution all right so we're we're trying to move from chemistry into you know you're looking at cells in the lab already animal cells and the parts of cells and so um cells are what what makes up our cells are atoms of the elements that are making up those molecules that in turn are making up macromolecules that are making up the cell organelles we divide the chemicals into two large groups and so our largest group is called the organics so organics include these are very large macromolecules that have lots and lots of hydrogens bonded to lots and lots of carbon so you have a carbon chain with lots of hydrogens bonded to it so that's just kind of the basics then in organics these are usually smaller molecules and they usually um dissociate or break down in water to release ions so typically those are those electrolytes and remember we said we had acid spaces and salts so we're going to see that in organics um in that category you have salts but you also have water and carbon dioxide so again they're smaller than the organic macromolecules um and they usually break down or dissociate in water to release ions so that makes them also electrolytes so we're going to look at the inorganic substances first and um water is our first inorganic substance again we're made up mostly of water so it's the most abundant compound in living things and remember it's a compound it's also a molecule makes up two-thirds of the weight of adults it is what we call a universal solvent so it is the most it's a really important solvent meaning that many things uh molecules will break down in water so most metabolic reactions occur in water and remember that the term metabolism means the sum of all the chemical reactions in the body so that's what metabolism means and metabolism in our body is occurring of course in water because we have water inside our cells and outside ourselves it's not pure water we do have electrolytes and and molecules in that water but absolutely it is the universal solvent we um have and you know our blood plasma is made up mostly of water lymph has water in it and of course these are transporting materials in the body so it is important in transportation water helps carry waste material it can absorb and transport heat and of course a lot of that's happening as part of blood plasma so just a few important characteristics of water there for us all right so here we're seeing um you know water molecules and we're seeing a crystal of sodium chloride so water is considered to be polar it's a polar molecule what does that mean well in a previous lecture i drew the hydrogen the hydrogens bonded to the oxygen molecule and i drew them at an angle and i said we talked about that later so remember that i said that oxygen and hydrogens are sharing electrons and that was indicated by the bond that i drew to each of those and those electrons then i said they orbit around the nucleus of the atom you know the oxygen atom and they also spend some time orbiting around the hydrogens but they spend more time orbiting around the atom of oxygen because oxygen is larger and so you can kind of think of it as its larger atom if you look at its weight on the um periodic chart it is larger than it's drawn larger here to represent that so you can think of it as hogging the electrons so electrons spend more time orbiting around the oxygen than the hydrogens so you can see below here is a delta sign but this is means has a slight negative charge on this end so you can see a little negative sign there then here we see the delta with the positive sign so this means that this end of the water molecule is slightly positive this is slightly negative that should make sense that makes sense right because the electrons spend more time around this portion of the molecule than here so electrons are spending more time here that makes it slightly negative whereas this end of the molecule is slightly positive that's what makes it polar it has two opposite ends so think of the earth you know has north pole and south pole those are ends and so we have a positive side and a slightly negative side that's important when molecules are polar that means they're going to react in a certain way with other molecules so what we're seeing here is why does salt this is sodium chloride right so why does crystals of salt dissolve in water so remember water is universal solvent it's because it is polar so when um the sodium crystals are introduced to you know water sodium has a positive charge chloride has a negative charge look what happens sodium is more attractive now to the water molecules so the sodium specifically is positive so it's an ion the sodium ion is attracted to the negative side of these water molecules and as a matter of fact the water molecules surround the sodium ion once it's surrounded by water molecules in this reaction it's not allowed to react anymore with the chloride same thing with chloride there's a larger attraction where it is negative so it's attracted to the positively charged hydrogens so when you put this crystal in water this is what happens chlorides get are attracted to the hydrogen so the water molecules water surrounds it and effectively keeps these separated okay so notice this is hydrated sodium hydrated chloride so they dissolve they broke apart the chemical bonds here broke and we formed new bonds so they are completely hydrated now and surrounded by water molecules so another inorganic um water is an inorganic molecule another one is oxygen and of course the whole reason we need oxygen in the body is for reactions occurring at the cellular level so our cells are undergoing a process called cellular respiration they're using the nutrients we bring in from our diet um they're you know we break that down of course and ourselves use that to drive a process called cellular respiration and a large part of that is happening in the mitochondria of our cells and oxygen is required for many parts of that process that's the whole reason we breathe in oxygen and of course um we're using those nutrients to create it says release energy what does that really mean when we release energy it's in the form of a molecule called atp that is the usable form of energy in the body so atp is what we're producing during cellular respiration and we need atp to the energy in atp to run lots of the chemical reactions that are occurring in the body and so that's why it says it's used to drive the cell's metabolism remember metabolism is the sum of all the chemical reactions in the body then here we have another inorganic substance called carbon dioxide and in the process of making atp during cellular respiration we create co2 and carbon dioxide is actually a waste product that we've produced and we exhale it that's why we exhale it we have to get rid of it it is also if it's a process it's produced during the process of cellular respiration so again that's happening in our cells of the body the mitochondria are actively playing a role in cellular respiration using oxygen releasing the waste product carbon dioxide um and our last inorganic um is inorganic salts they're also called minerals so these are salts you know the sources of ions so we just broke down sodium chloride that's a salt it's inorganic um so sodium chloride potassium calcium magnesium phosphate carbonate bicarbonate and sulfate so these are inorganic salts and remember they are our electrolytes as well they have a charge because they're ions and they conduct electricity and they when they break down in solution or in water they release ions so that's why they're also called electrolytes but these are the last of our inorganic oh sorry so these electrolytes play an important role in many of the body's metabolic processes all right so our largest class of chemical compounds then we had inorganics and the other class is organic compounds and you have one or more atoms of carbon so really many more than one so you have lots of carbon atoms linked together through covalent bonds and remember that means they're sharing electrons um and so not only do you have carbons linked to each other but you have carbons linked to other elements as well and this is typically hydrogen oxygen and nitrogen so covalently bonded i might be able to draw a little bit here so for example you have a carbon [Music] and often a carbon is going to want to form four bonds four covalent bonds remember that each of these bonds represents two electrons being shared and so often you're seeing depending on the molecule how many carbons you have they're going to be linked to each other and they're going to have bonds now typically for example this would be hydrogen it's really hard to draw the mouse okay and that tells you that the carbon is sharing electrons with this hydrogen this hydrogen with this carbon with this carbon so again you'd have a really long chain and when you start looking at the organics with the four classes of organic molecules in your textbook which you should be doing you're going to see lots of carbons hydrogens and of course some oxygens as well so i'm going to erase this because typically what you find maybe let me draw again when you have oxygen we look at oxygen how many electrons it needs to share oxygen and carbon are going to share four electrons so remember carbon forms four covalent bonds and so one two three four this is a double covalent bond to represent the sharing of four electrons between this carbon and this oxygen okay let's erase all my doodles here all right so the next thing is going to be an assignment for you guys and i'm going to work through this assignment in a separate um video but you can go ahead and be pulling this information out of your chapter i guess i need to stop that sorry okay so here we go so we've looked at organics and in your chapter i want you to look at the four organic classes so what are the classes of organic molecules i'm going to go ahead and tell you that they are proteins lipids carbohydrates and nucleic acids i really think your book starts with carbohydrates but that doesn't matter but you need to know what the four classes are you need to know some functions of each some examples of each and recognize what are the structures that make up each so what are the building blocks so for example what are the building blocks of proteins how do we build a protein what do we build it out of carbohydrates what are the building blocks lipids so what are the basic structures that make up these um organic classes and so i'm going to have a separate video where i take you through an exercise but you need to do this first pull this information out of your chapter using that student guide um and or just reading it pulling out on a separate sheet of paper is fine uh and then i'm going to go over in a separate video um an activity we would do in class for example in that activity you're going to put it with your textbook homework for the class and i'll give you more information on that in the next video i'm also going to post another video of someone another person going over organic molecules as well just to kind of change it up a little bit for you all right that's it for this section