So let's look at hydrophilic and hydrophobic because these have to do with water as a solvent. So some things dissolve in water and some things don't dissolve in water. So hydrophilic, hydro means water, philic means loving. Hydrophobic, hydro means water. phobic means fearing or I like to say hating because it's easier because it's the opposite of loving right?
So in a hydrophilic molecule it loves water which just means it's going to dissolve in water, readily dissolve in water. That's all it means. So these are molecules that have a positive or a negative charge.
Ionic compounds are great examples. Salt, any type of salt is going to be an ionic compound and you're going to readily dissolve in water. Another one are going to be polar covalent compounds.
So water itself is a polar covalent compound and other polar covalent compounds dissolve in water. ethanol will dissolve in water. So example, salt and ions. Those are the easiest ones to think about.
Ions are going to play a huge role when we're talking about biological processes and metabolism. Hydrophobic is going to be different. So let me give you an example of a biological molecule that is hydrophilic, that loves water, amino acids.
So if you look at this molecule, you can see that double... bonded oxygen and that OH group, that hydroxide group on the right-hand side. And then you can see the amine group, the nitrogen and the two hydrogens on the left-hand side.
Those are both going to be charged groups. So that's a polar molecule. I have a very uneven charge distribution in that molecule.
So amino acids readily dissolve in water. So if I dump some amino acids in water, they're not going to clump up and form like a little bubble of amino acids. They'll distribute through the water.
And that's important biologically because, you know. That's how we move them places. Hydrophobic interactions, water-ferring. So in a hydrophobic interaction, these are typically going to be nonpolar covalent compounds. And so there's going to be an even charge distribution throughout.
It's not like one side's negative and the other side's positive. These are nonpolar molecules, nonpolar. That's important.
Now, the most important nonpolar molecules were... we're going to talk about are fats. So oil, you know, doesn't mix with water. Fats don't mix with water either.
So biologically, lipids are hydrophobic. And the example I'm going to give you is not the standard lipid that we're going to draw in class. This is a steroid.
Specifically, it's testosterone. And if you look, it looks like it should be a polar molecule because you've got the oxygen and the hydroxide. But if you actually look at how it behaves, it is a nonpolar molecule because... The charges are evenly distributed.
They're not unevenly distributed. So this testosterone steroid is nonpolar. What this means is that if you put testosterone in water, it doesn't dissolve. It also means if you put testosterone in fat, it does dissolve because light dissolves light. Hydrophilic will dissolve in polar.
Polar dissolves in polar. Nonpolar dissolves in nonpolar. So fat and water don't mix.
We know that, right? So you just have to keep straight that water is... is a polar molecule, molecules that are polar are hydrophilic. Fats are a nonpolar molecule, and molecules that are nonpolar are hydrophobic. So that's that.