Introduction- Organic Compounds, Functional Groups and Linkages.

Much of biochemistry deals with biopolymers that are macromolecules created by joining many smaller organic molecules (monomers) via condensation (removal of element of water). Each monomer that makes a macromolecular chain is called a residue.

In some cases like carbohydrates (more on it later), a single monomer or residue is repeated many times, in other cases like proteins and nucleic acids, a variety of residues are connected in a specific order.

The residues are added and converted into a polymer by repeating the same enzyme catalyzed reaction. Thus all of the residues in a biopolymer are aligned in the same direction.

Biopolymers have properties that are very different from those of their constituent monomers. Example: Starch is not soluble in water and does not taste sweet although it is a polymer of the sugar Glucose, which has both those properties.  So we can conclude that each new level of organization results in properties that cannot be predicted just from those of the previous level.

The levels of complexity in increasing order are atoms, then molecules, then biopolymers, then organelles then cells, tissue, organ, and all organisms and systems.


The types of organic compounds, functional groups and linkages commonly seen in biochemistry are;

Organic Compounds, Functional Groups and Linkages.

PS: Under most biological conditions, carboxylic acids exist as carboxylate anions: COO and amines exist as ammonium ions: NH3+ .

Please make sure you memorize the names and structures of the functional groups.

Biochemical reactions involve specific chemical bonds or parts of molecules called functional groups which we will deal with several times.

  • Ester and Ether are common linkages found in fatty acids and lipids.
  • Amide linkages are found in proteins.
  • Phosphate ester and Phosphoanhydride linkages occur in nucleotides.