Functional Groups

STRUCTURE: (-OH) A hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Not hydroxyde ion OH-) NAME OF COMPUND: Alcohols (their specific names usually end in -ol) PROPERTIES: polar as a result of the electrons spending more time near the electronegative oxygen atom. Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars.

STRUCTURE: carbonyl group (XO) consists of a carbon atom joined to an oxygen atom by a double bondNAME OF COMPOUND: Ketones if the carbonyl group is within a carbon skeleton Aldehydes if the carbonyl group is at the end of the carbon skeleton FUNCTION: • A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. • These two groups are also found in sugars, giving rise to two major groups of sugars: aldoses (containing an aldehyde) and ketoses (containing a ketone).

STRUCTURE: When an oxygen atom is doublebonded to a carbon atom that is also bonded to an -oH group, the entire assembly of atoms is called a carboxyl group (-COOH).NAME OF COMPOUND: carboxylic acids, or organic acids FUNCTION: • Has acidic properties (is a source of hydrogen ions) because the covalent bond between oxygen and hydrogen is so polar • Found in cells in the ionized form with a charge of 1- and called a carboxylate ion (here, specifically, the acetate ion).

STRUCTURE: The amino group (-NH₂) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton. NAME: Amines FUNCTION: • Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms). • Ionized, with a charge oF 1+ under cellular conditions.

STRUCTURE: The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape. NAME: Thiols FUNCTION: • Two sulfhydryl groups can react, forming a covalent bond. This "cross-linking" helps stabilize protein structure • Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be "permanently" curled by shaping it around curlers, then breaking and re-forming the crosslinking bonds.

STRUCTURE: In a phosphate group, 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 (-OPO₃^2-, abbreviated P) is an ionized form of a phosphoric acid group (-OPO3H2; note the two hydrogens). NAME: Organic Phosphates FUNCTION: • Contributes negative charge to the molecule of which it is a part (2- when at the end of a molecule, as above; 1when located internally in A chain of phosphates). • Has the potential to react with water, releasing energy.

STRUCTURE: Amethyl group consists of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom. NAME: Methylated compounds FUNCTION: • Addition of a methyl group to DNA, or to molecules bound to DNA, affects expression of genes. • Arrangement of methyl groups in male and female sex hormones affects their shape and function