Functional Groups

Hydroxyl Group (-OH)

A functional group consisting of a hydrogen atom covalently bonded to an oxygen atom (-OH).

• Makes the molecule an alcohol when attached to a carbon strand.

• Polar due to the electronegativity difference between oxygen and hydrogen. This polarity allows hydroxyl groups to form hydrogen bonds with water molecules.

• Soluble in water, facilitating the dissolution of organic molecules in aqueous solutions.

Sulfhydral Group (-SH)

A functional group containing a sulfur atom bonded to a hydrogen atom (-SH).

• Less polar than hydroxyl groups due to the lower electronegativity of sulfur compared to oxygen.

• Can form disulfide bridges (-S-S) through oxidation, which are important in protein structure.

• Found in amino acids like cysteine and methionine, contributing to protein folding and stability.

Carbonyl Group

A functional group containing a carbon atom double-bonded to an oxygen atom (C=O).

• If the carbonyl group is at the end of the carbon skeleton, the molecule is an aldehyde.

• If the carbonyl group is within the carbon skeleton, the molecule is a ketone.

• The carbonyl group is polar due to the electronegativity difference between carbon and oxygen.

• Carbonyl groups can participate in hydrogen bonding as hydrogen bond acceptors.

• Important in sugars, such as ketoses (containing ketone groups) and aldoses (containing aldehyde groups).

Carboxyl Group (-COOH)

A functional group consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (-COOH).

• Carboxyl groups are acidic due to the ability to donate a proton (H^+).

• Can form hydrogen bonds with water molecules, enhancing solubility in aqueous solutions.

• Important in amino acids (as part of the amino acid structure) and fatty acids.

• Can react with alcohols to form esters, which are important in lipid formation.

Amino Group (-NH_2)

A functional group consisting of a nitrogen atom bonded to two hydrogen atoms and the carbon skeleton.

• Acts as a base; can pick up a proton from the surrounding solution (water in living organisms).
• Can form hydrogen bonds.
• Found in amino acids (building blocks of proteins) and nucleic acids (DNA and RNA).
• The amino group is basic and can accept a proton (H^+), becoming positively charged (NH_3^+) under cellular conditions.

Methyl Group

One carbon 3 hydrogen, branches off of carbon chain, doesn’t dissolve naturally in water

Phosphate group

Acidic

Donates protons

Protested when attached to hydrogen

Functional Groups

functional groups are specific arrangements of atoms within molecules that dictate the molecule's properties and reactivity. They are like chemical "building blocks" that confer characteristic behaviors on the larger molecule, regardless of the rest of its structure. Important functional groups in biology include hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl.