Understanding the Four Molecules of Life: Building Blocks Explained

Hi. It's Mr. Andersen and in this podcast I'm going to talk about the Molecules of Life. The first time I learned this I was pretty amazed. But basically the way the world

works is that we eat food. And then the building blocks of that food we weave together to make living things. And so this right here is called a Dave Thomas. Dave Thomas is the founder of Wendy's. But Dave Thomas and his body was made up of building blocks that came from

the food that he created. In other words the proteins in the burger are broken down into amino acids. And those make the proteins in him. Or the sugars in the carbohydrates of the bun are broken down to make sugars that are used in cellular respiration to make ATP

to move the materials inside him. Or the fat inside the burger is used to make the lipids inside the cell membranes of a Dave Thomas. He's actually really fascinating guy when I read about him a little bit. I didn't know this be he worked for Colonel Sanders in the

KFC. So it's worth studying the wikipedia a little bit on Dave Thomas. Also a war hero. So cool. But basically life is built on carbon. And the reason life is built on carbon is that carbon has four valence electrons. In other words it has six protons. That means

it has six electrons. And two electrons in the first level, but it has one electron in each of these, if we were to draw a Lewis Dot Diagram. One of these in each of those outer valence shells. And so basically it's really good at bonding. And so the reason

life is made up of carbon is because it makes fairly stable large carbon based molecules. And that's what we are. If it weren't carbon then maybe it would be silicon, which sits right below this. I remember watching a Star Trek episode way back in the day where there

are these giant rock animals called the Horta. And basically this right here is Spock mind-melding with a Horta. But based in silicon. And so if we were to find life somewhere out there in the universe maybe silica would be an example of that. And my computer is made up of silica

which is about as close to life as we have on our planet. So the first thing you should understand is the idea of what a functional group is. So life is made up of carbon. These huge carbon chains. That's what DNA is pretty much made up of, carbon and hydrogen. But

there are things around the outside that are called functional groups. And those give functionality. They give behavior to the chemicals. And so if we go through these, starting with the first one. This would be a carboxyl group. There's going to be a carbon right here at

the middle. And so we could abbreviate a carboxyl group by just writing COOH. By basically a carboxyl group is going to donate this hydrogen ion. And so it will make things that are carboxylic acid. This carboxyl group and the amino group actually form amino acids. Next one would

be the carbonyl group. Carbonyl group has a carbon right here. If it's in the middle we call it a keytone. At the end it's called an aldehyde. So formaldehyde would be an example of that. This would be a methyl group. An methyl group is going to be a carbon with

three hydrogens around the outside of it. Methyl groups would be important in methylation. So basically what they can do, DNA would be a great example of that, is they can methylate these big carbon compounds. Make them non-functional. Amino group would be another one. Amino group

is going to have a NH2. So it's got nitrogen. And we need nitrogen to survive. And the reason we need nitrogen is to make amino acids. And basically an amino acid, which is the building block of proteins are made up of carboxyl group and amino group. Next one would be the

phosphate. Phosphate, you may know this, it's actually what's on the end of ATP. It's what we use for energy transfer. Also it's used to build DNA for example. So transfer of energy would be a phosphate group. And then finally we have the hydroxyl group. Hydroxyl group

is going to be an OH. What that does is make it polar. And so it makes it readily dissolvable. And so if you learn these six in biology, just what they are, you're going to see, even in this presentation, that they're going to start showing up. And you can predict some

of the properties. So amino groups will grab onto a hydrogen ion. Become bases. And so there's a lot of things you can learn from functional groups. But the first thing you want to do is simply memorize them. Now we get to the actual molecules of life which

are mostly polymers. Now know this, that polymers are made up of monomers. And so monomers are the building blocks. And polymers are these large macromolecules. And there's only four in biology that you have to learn. So it's pretty easy. But those polymers are built

through a process called dehydration. So if we look right here, this is one amino acid. And this is another amino acid. You could see right here again that there's an amino group on this side. There's a carboxyl group on that side. But basically if we look right

here in the middle. If we have two amino acids right next to each other, if I were to remove just this section right here, it's an oxygen and two hydrogens, what am I removing? I'm removing H2O. And that's called water. And so we call that a dehydration reaction because

you're removing water. Just like when you're dehydrated, you don't have enough water. So you remove that water and we form a covalent bond in the middle. That would be a peptide bond. And so the proteins inside my hair and my nails and my skin and all of that is made

up of amino acids that are attached together. Each time we attach two amino acids, we've got to lose a water. Likewise if we want to break it apart, so let's say I eat a burger. One of those Wendy's burgers, and I want to breakdown the proteins and make amino acids

out of it, that I can use inside my body, what would be the reaction there? That's called hydrolysis. So hydrolysis now is hydro, water, lysis means to break, and so we're adding a water here in the middle and we're breaking that bond apart. And so now we have two amino

acids. And so how do you build proteins? Through dehydration reaction. How do you break them down? Hydrolysis. How do you build nucleic acids, like DNA? Dehydration reaction. How do you break it down? You can do that through hydrolysis. And so even carbohydrates, the

same way. And so let's get to those four major macromolecules. The first one is going to be called nucleic acids. Nucleic acids, the two big ones you should understand are RNA and DNA. DNA stores information inside the cell. RNA is kind of a slave to the DNA, but

it does work. So these right here would be polymers, large macromolecules. What are the building blocks? It's going to be these nucleotides. And so this would be a nucleotide that builds, this would be one that builds DNA. So it's got a base a sugar and a phosphate. And so

we simply attach these over and over and over again. And so it would fit right in here. And that would be one nucleotide. So we attach them over and over and over again. Again we do that through a dehydration reaction. And eventually you have DNA. So where do we get

our DNA? We eat our food and we break it down into monomers and then we can weave that back into the stuff of life. If we go to proteins, proteins again are made up of amino acids. Again, here's that amino group. Right here would be the carboxyl group. Right here in

the middle of an amino acid we have a carbon and a hydrogen. And then on the side we have an R or side chain. And so basically this is going to be different in every amino acid. And so just like we have 26 letters that make all of the words in our alphabet, there are

only 20 amino acids that humans need to survive. And these are all 20 amino acids. And if you look at them, don't memorize them. That would be silly, but if you look at them what you'll see is, here it is. Here is our carboxyl group, our amino group. And all of them have carboxyl,

amino, carboxyl, amino. But if you look on the side, this R or side chain is going to be different in every amino acid. So this would be one side chain. That would be another side chain. That would be another side chain. And we have a few properties. So like these

ones would all be positive. These ones would be negative. These ones right here would be uncharged so, excuse me charged. And you can see like here's a hydroxyl group, here's a hydroxyl group. Here's an amino, an amino group and so that's why they're charged. And

so basically what is a protein? A protein is this huge three dimensional structure that's made up of sometimes thousands of amino acids attached together. And so why do they look the way they do? Well the order of them is important. And DNA holds that. But once you

have all those amino acids attached together, it will basically look like this where you have all the backbone. But on the side you're going to have all your R or side chains. And so basically once you build a polypeptide or protein, it's then going to fold into a

characteristic shape like this. Why is it going to do that? Well first of all they're all going to be all of these alpha helices. And basically those are built on hydrogen bonds. Then all the polar side chains will fold to the outside of the protein. And all

the non-polar hide in the middle. You'll have positive attached to negative. And sometimes we refer to this all as the tertiary structure. And then the quaternary structure would be, you know, having more then one polypeptide attached together. But when you look at me

you're looking at proteins. And that proteins are all built of these monomers which are amino acids. Next one then would be the lipids. Lipids basically, there's one thing that ties those all together. They're a carbon, a carbon, a carbon, a carbon, a carbon, a carbon, a

carbon, a carbon, a carbon, a carbon and then hydrogen around the outside. So we call these things hydrocarbons. And so this would be a fatty acid. But this would be like a triglyceride. It makes that burger. That fatness of the burger really good. This would be a phospholipid.

And that would be inside the membranes of all living material. Or cholesterol. You can see that hydrocarbon chain right here. These things are used for energy. But they also build up membranes. One more important thing about them is that they come in two different

types, saturated and unsaturated. Basically if you're saturated it means you're straight because you have hydrogen around the whole thing. If you're unsaturated you have a double bond in the middle. And so things like fat, like butter, animal fat, are going to be saturated.

Unsaturated would be things like an olive oil. Because if they're bent they can't quite get next to each other and so they form a liquid at room temperature. We can make them saturated by bubbling hydrogen through it. And transforming that fat. So you maybe heard

of transfats. And then the last one is going to be carbohydrates. Carbohydrates actually come in three different types. We have monosaccharides. The quintessential example is glucose. We have disaccharides. And example of that would be sucrose. And then we have these huge polysaccharides,

which are hundreds and hundreds and hundred of glucose molecules attached together. Or saccharide sugar molecules attached together. So basically when you're eating a potato or when you're eating bread or when you're eating anything that has starch, it is a bunch of

sugar molecules. So there's one, another, another, another. And so they're all attached together using covalent bonds. And so if I want to breakdown carbohydrates what do I do? Well I have to snip that off. Hydrolysis. Break those into sugars and then I can use

them in cellular respiration. And so those are the molecules of life. Again, there's only four of them. But if you think back to that burger and how that burger eventually becomes you, it's a pretty cool process. And I hope that's helpful.