Answer: They possess different functional groups.
Step-by-step explanation:
Organic compounds are molecules composed of many carbon atoms bound together and in turn bound to hydrogen atoms. These molecules form the lipids, proteins, carbohydrates and nucleic acids that constitute all living beings. The reason why there is so much variety of organic molecules is because each one can have one or several functional groups in different positions, which gives them unique properties.
So a functional group is a group of atoms linked in a certain way, which present a specific physical-chemical structure and properties that characterise the organic compounds that contain them.
Examples are:
- Lipids: A carboxylic acid
- Proteins: A carboxyl group and an amino group
- Carbohydrates: An aldehyde or ketone group
- Nucleic acids, Nucleotides: A phosphate group