 So in organic chemistry we often talk about functional groups and functional groups are groups of atoms that can be added to hydrocarbon chain for example. And so I've listed some of the major functional groups that students in biology might be interested in. One group is a hydroxyl group and this is what alcohols are all about. So if you see OH attached to an organic compound that you know that's a functional group and maybe an alcohol. Another group is a double bonded oxygen attached to the carbon and this is called a carbonyl group. If the double bonded oxygen is at the end of a chain then that particular substance is called an aldehyde. If that double bonded oxygen is in the middle of the chain or is not on the end then that's a substance called a ketone. Then we can have carboxylic acid groups. Vinegar for example has a carboxylic acid group attached to it and that's a carbon with both a double bonded oxygen and a hydroxyl group attached to it. Then there's a group called a mean group and that's a nitrogen with two hydrogens attached to it. And then we have a phosphate group and the phosphate group is an oxygen with the phosphate or phosphorus and three octazones attached and you see that carries a charge of negative two.