IB Biology Topic B1.2: Proteins Key Definitions

Condensation is a reaction where two molecules combine, releasing water.

Denaturation is the process by which the three-dimensional structure of an enzyme is altered, leading to the loss of its function.

Disulfide bonds are covalent bonds that form between two cysteine amino acids.

Organisms that thrive in extreme conditions.

Globular proteins are compact, spherical proteins that are typically soluble in water. Their structure results from the folding of the polypeptide chain into a tightly packed three-dimensional shape.

A non-polar amino acid side chain composed mainly of carbon and hydrogen atoms. Hydrophobic R-groups do not form hydrogen bonds with water and tend to be positioned in the interior of globular proteins or within the lipid bilayer of membrane proteins.

Definition:
Ionic bonds form between R-groups that carry opposite charges.

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

pH is a measure of how acidic or basic a solution is, ranging from 0 (very acidic) to 14 (very basic).

The primary structure of a protein is the linear sequence of amino acids in its polypeptide chain.

The quaternary structure of a protein refers to the specific three-dimensional arrangement of multiple polypeptide chains (subunits) in a single functional protein.

The variable side chain attached to the central carbon of an amino acid. The R-group determines the chemical properties of each amino acid and is the only part of the structure that differs between the 20 amino acids used in proteins.

The secondary structure of a protein refers to the regular, repeating patterns that form when a polypeptide chain folds. These patterns arise from interactions between the amino acids in the backbone of the protein.

The tertiary structure of a protein refers to the complete three-dimensional folding of a single polypeptide chain.