Comprehensive Guide to Carbohydrates: Types, Functions, and Health Impacts

foreign [Music] 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