IB Biology B1.2 Proteins

Hydrophobic

The property of molecules that do not mix with water

Hydrophilic

Molecules or substances that have a strong affinity for water, meaning they are 'water-loving'

Polar

Molecules where electrons are not shared equally within a covalent bond, resulting in partial positive and negative charges on different parts of the molecule

Nonpolar

Molecules that lack a significant separation of charge, meaning the electrical charges are evenly distributed across the molecule

Denaturation

The process where a protein or nucleic acid molecule loses its native three-dimensional structure, leading to a loss of its biological function

Primary Protein Structure

The specific number and sequence of amino acids linked together to form a polypeptide chain

Secondary Protein Structure

The local spatial arrangement of the polypeptide backbone due to hydrogen bonds between the backbone atoms. Particularly alpha-helices and beta-pleated-sheets.

Tertiary Protein Structure

The overall three-dimensional (3D) shape of a single polypeptide chain. Formed by interactions and bonds between R-Groups. Particularly hydrogen bonds, ionic bonds, disulfide bridges, & hydrophobic interactions.

Quaternary Protein Structure

The arrangement of multiple polypeptide chains (subunits) within a single protein complex

Conjugated Protein

A protein that has a prosthetic group attached to it

Prosthetic Group

A non-protein component that is tightly bound to a protein and is essential for its function

Globular Protein

Proteins that have a generally spherical shape, compact structure, and are soluble in water

Fibrous Protein

Structural proteins characterized by their elongated, thread-like shape and their insolubility in water

Amino acid

Organic compounds that contain both amino and carboxylic acid functional groups. Monomers of protein

Amine Group

A functional group consisting of a nitrogen atom bonded to two hydrogen atoms (NH2)

Carboxylic Acid Group

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

Side Chain (R Group)

A variable group of atoms attached to the central carbon atom of an amino acid

Dipeptide

A molecule composed of two amino acids linked together by a single peptide bond

Peptide Bond

A covalent bond formed between the carboxyl group of one amino acid and the amino group of another.

Polypeptide

A chain of amino acids linked together by peptide bonds

Essential Amino Acids

Amino Acids that the human body cannot synthesize on its own and therefore must be obtained through the diet

Non-Essential Amino Acids

Amino Acids that the human body can synthesize internally, meaning they don't need to be obtained through dietary intake