Some Simple Types of Organic Molecules

and their functional groups


Organic molecules with a hydroxyl group (-OH).

Methanol [CH3OH] and ethanol (beverage alcohol)[CH3CH2OH] are common examples.

Sugars are also alcohols.

Carboxylic Acids

Contain one or more carboxyl groups [-COOH].

Many of the intermediates in the breakdown of foodstuffs by cellular respiration are carboxylic acids. [Link]


Contain a carbon atom to which is attached one hydrogen atom and — by a


Glycoproteins have carbohydrate attached to them — a process called glycosylation.

The attachment is a covalent linkage to:

  • the hydroxyl (-OH) group of the R group of serine or threonine - called "O-linked" in both cases or to
  • the amino group (-NH2) in the R group of asparagine - called "N-linked".

The carbohydrate consists of short, usually branched, chains of

  • plain sugars (e.g., glucose, galactose);
  • amino sugars (sugars with an amino group, e.g.,


Nucleic acids are linear, unbranched polymers of nucleotides.

Nucleotides consist of three parts:


A five-carbon sugar (hence a pentose). Two kinds are found:

  • deoxyribose, which has a hydrogen atom attached to its #2 carbon atom (designated 2'), and
  • ribose, which has a hydroxyl group there.

Deoxyribose-containing nucleotides, the deoxyribonucleotides, are the monomers of deoxyribonucleic acids (DNA).

Ribose-containing nucleotides, the ribonucleotides, are the