The Seven Functional Groups

Hydroxyl Group

-OH

Structure: a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH-.)

Example: Alcohols (specific names ending in -ol) or Hydroxides

Properties: Is polar as a result of the electrons spending more time near the electronegative oxygen atom.

Carbs, Proteins, Nucleic Acids, Lipids

Carbonyl Group

C=O

Structure: consists of a carbon atom joined to an oxygen atom by a double bond.

Examples: keytones (if the carbonyl group is within a carbon skeleton) and aldehydes (if the carbonyl group is at the end of the carbon skeleton)

Properties: structural isomers with different properties

Carbs, Nucleic Acids

Carboxyl Group

COOH

Structure: an oxygen atom is double-bonded to a carbon

atom that is also bonded to an —OH group, the entire

assembly of atoms is called a carboxyl group (—COOH).

Examples: Carboxylic acids or Organic Acids

Properties: Has acidic properties because the covalent bond between oxygen and hydrogen is polar.

fatty and amino acids

Amino Group Group

NH2

Structure: consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton.

Examples: Amines

Properties: Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms).

All amino acids

Sulfhydryl Group

-SH

Structure: consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape.

Examples: Thiols

Properties: Two sulfhydryl groups can react, forming a

covalent bond. This "cross-linking" helps stabilize protein structure.

Phosphate Group

PO4

Structure: a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges. The phosphate group (—OPO32-, abbreviated) is an ionized form of a phosphoric acid group (—OPO3H2).

Examples: Organic Phosphates

Properties: Contributes negative charge to the molecule of which it is a part (2- when at the end of a molecule; 1- when located internally in a chain of phosphates).

Methyl Group

CH3

Structure: consists of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom.

Examples: Methylated compounds

Properties: Addition of a methyl group to DNA, or to molecules bound to DNA, affects expression of genes.