Carbohydrates

foreign in this podcast I'm going to talk about carbohydrates when I say the word carbohydrates you might think about the starch that's found in this bread or maybe in this pasta as a biology teacher I immediately think of sugar because that's going to be the building block upon which most carbohydrates are made but you should also know that aside from providing energy for us they also provide structure and so cellulose that's found in plants is going to be a polysaccharide or the chitin that's found in the exoskeleton of an insect or the building block of

fungi is going to be a carbohydrate and so they give us energy but they also give us structure sugars in science we call saccharides and the reason I wrote carbohydrates inside these hexagons is that that's how sugars are essentially put together and so if we have just one of these sugar molecules we call that a monosaccharide so an example could be glucose if we have two of them together we call that a disaccharide an example could be table sugar or sucrose it's actually one glucose and one fructose molecule if we have about three to ten

sugar molecules we call that an oligosaccharide and then if we have a whole bunch of sugar molecules attached together we call that a polysaccharide and so glycogen would be an example of that and so basically the empirical formula of all carbohydrates is going to be the same in other words we have a ratio of 1 to 2 to 1 in the amounts of carbon hydrogen and oxygen so we have twice as much hydrogen as we do carbon and oxygen can you see why they're called carbohydrates we've got a carbon out here and then we have

water so it's a carbohydrate good way to remember that if we look at a simple monosaccharide it's going to have six carbon 12 hydrogen and six oxygen and so the the simplest the sugar upon which life is built is called glucose and so glucose has six carbons we could look at them there's one here here here here here and here so they're going to be at the junction points on this ring in an aqueous solution or in water they're going to form these rings but you can also see that there's going to be a lot

of oxygen so we have all these hydroxyl groups around the outside and that makes sugars readily dissolvable in water and so glucose is used in cellular respiration it's produced by plant in photosynthesis so they can use it in respiration so it's the building block a lot of the different sugars that I'm going to show you in this podcast are built upon glucose but there are other ones we've got the fructose fructose is going to be a five you can see it's a five-sided sugar it's found it's going to be a little sweeter than glucose and

it's going to be found like in fruit or high fructose corn syrup and then we have galactose and galactose is going to be a little less sweet than glucose but these are the basic three monosaccharides what's cool about these they all can can readily be moved into our blood supply and so these are flowing through your blood right now these little monosaccharides if you ate pasta for example we first have to break that down into its monosaccharides before we can move it through the blood and then into the cells in our body so what are

disaccharides then disaccharides are going to be two sugar molecules attached together and so the table sugar that's found in these sugar cubes is going to be sucrose and so it is a glucose molecule attached to a fructose and so when that goes into my body I have an enzyme called succrese that has to break that down into its monosaccharides before it can actually use it or here's another one the milk sugar so lactose is going to be of glucose and a galactose chemically attracted chemically bonded together and so if you want to break down lactose

you have to have an enzyme called lactase now if you're lactose intolerant what does that mean you just lack the enzyme to break lactose down into its two monosaccharides and so you're going to feel a little irritation in your gut and that's because we can't break it down now that seems to be there's some really cool studies you could read on on lactose tolerance or intolerance and it's been naturally selected in other words if your ancestors had domesticated cattle it made sense for them to drink milk later on in their life but most people just

drink milk when they were young and so they quit producing that lactase enzyme okay let's go to oligosaccharides oligosaccharides are going to be like three to ten different sugar molecules they're important in biology in one pretty important part and that is in the production of these which are called glycoproteins so we're in the cell membrane and these which are going to be glycolipids if you look at the glyco part or the sugar part that's going to be just a few sugar molecules attached together and these are really important for example attaching to The extracellular Matrix

they're important in identifying what type of a cell it is here's an interesting note I learned on Wikipedia if you were to eat carrots carrots are a wonderful wonderful source of oligosaccharides however you can't get the sugar molecules out of it until you've cooked the carrots for about an hour to release those oligosaccharides but again if you're not getting them in your diet we can synthesize those inside the cell now let's look at this number right here as we go from oligosaccharides to polysaccharides and look how how much that jumped and so when we're talking

about starch for example what is starch starch is going to be hundreds of these glucose molecules attached over and over and over again and so the starch that's found in a potato or if we dry it out it's going to look like this is going to be hundreds of sugar molecules attached over and over and over again now why are plants doing this why are they making these large molecules they're storing energy in the starch molecules so they can use it by chopping it down into individual monosaccharides now can we do that you bet we've

got glycogen so glycogen is essentially a macro macromolecule and so it's going to have thousands of glucose molecules uh attracted together or chemically bonded together you can see what how monstrous this looks with all these individual glucose molecules and we're going to store that in the liver and so if you are carbo loading what are you really doing you're eating a bunch of starch you're breaking those down into monosaccharides and then you're reattaching those again and you're storing them in our liver as glycogen and so we can get to those stores eventually when we need

it we can chop chop up those monosaccharides and we can use them in the cell but we also get structure remember and so cellulose that makes up that structure in a lot of plants you can see here here it's going to be a bunch of sugar molecules attached over and over again but we're going to have these hydrogen bonds that cross bond between the different polysaccharides makes them incredibly durable if you were to eat wood don't um but you you don't have the enzymes to break it down inside your gut and so it's going to

go in as wood and it's going to come out as wood and so if we want to break down cellulose um we have to get help and we have to get microscopic health and help and so like a cow for example is going to have a bunch of bacteria and other microscopic life that lives in their gut that can break down that cellulose and so they can eventually get to sugars but it's not that easy so how do we do all this building and how do we do all this breaking well there's basically two processes

since it's a polymer we can use hydrolysis hydrolysis is simply breaking the sugars and so right here we have a glucose or excuse me a lactose molecule you can see it's a disaccharide and so what we can do is we can add a water and when we add a water we can break this Bond right here and we can make two monosaccharides and so hydrolysis simply breaking them apart enzymes help on this as well and then a dehydration reaction is when we're going to have two monosaccharides and we go in the other direction so when

we're actually making lactose we're taking two monosaccharides we're losing a water and then we're making that covalent bond between them and so again we can build we can make them smaller and then we can eventually break them down in respiration now if we were to look at sugars are they a good thing well evolutionarily they're very important why do we love sugar so much it's because sugar is usually an indicator of fruit and fruit is going to have a lot of other vitamins in it that we need and so humans are essentially programmed to love

sugar sadly what we've done is we've started to put sugar in everything and so this I didn't even know this they made this this is a double Big Gulp so if you had this much soda it's made of high fructose corn syrup so basically we're enzymatically breaking down corn to make this fructose this really sweet sugar and it's killing us we're seeing an increase in heart disease and increase in diabetes as a result to that and so a little bit of sugar is good we need it for energy obviously but too much is probably bad

and I hope that was helpful