2.1.2 Proteins

Amino Acids

Building blocks of proteins, consisting of a central carbon attached to a hydrogen atom, a carboxylic acid group, an amine group, and a variable R-group.

Peptide Bond

The bond formed between two amino acids during a condensation reaction, creating a dipeptide.

Polypeptide Chain

A chain of amino acids linked by peptide bonds, forming the primary structure of a protein.

Primary Structure

The sequence of amino acids in a polypeptide chain, held together by peptide bonds.

Secondary Structure

The coiling (alpha-helix) or folding (beta-pleated sheet) of a polypeptide chain due to hydrogen bonding.

Tertiary Structure

The 3D shape of a polypeptide chain determined by irregular folding, held by various bonds like hydrogen, ionic, disulfide, and hydrophobic interactions.

Quaternary Structure

The structure formed by the association of multiple polypeptide chains, each called a subunit, held together by bonds between R-groups.

Globular Protein

Proteins with a spherical shape, soluble in water, and diverse amino acid composition, often involved in metabolic functions.

Fibrous Protein

Proteins with long, fibrous shapes, insoluble in water, and repetitive amino acid sequences, typically serving structural roles.

Prosthetic Group

Non-amino acid molecules necessary for the structure and function of certain proteins, forming conjugated proteins.

Soluble

Capable of being dissolved in water.

Active site

Specific region of a protein that catalyzes a chemical reaction.

Insulin

Hormone released by the pancreas to regulate blood sugar levels.

Globular

Protein shape that allows binding to receptors on cells.

Keratin

Protein providing strength to structures like hair, skin, and nails.

Fibrous

Protein structure that is inelastic and tough.

Disulfide bonds

Bonds that determine the flexibility of a protein molecule.