AP BIO, Functional Groups

Hello,

I working through the AP Bio course just to prep for going back to school.

I am learning about chemistry and the functional groups. I understand how to tell which functional group a molecule has, but I don't understand how to use those functional groups to identify if something is a protein, alcohol, nucleic acid, carbohydrate, phospholipid, etc. 

How do I identify what type of molecule it is?

Thanks for the help!