IB Biology HL - Proteins (B1.2) Vocabulary

Flashcards for IB Biology HL - Proteins (B1.2)

Amino Acid

Monomer of proteins; there are 20 different amino acids in nature.

Amine Group

Basic functional group found in amino acids (-NH₂).

Carboxyl Group

Acidic functional group found in amino acids (-COOH).

Alpha Carbon

Central carbon (Cα) in an amino acid, bonded to the amine, carboxyl, hydrogen, and R group.

R Group (Side Chain)

Determines the properties and identity of each amino acid.

Peptide Bond

Covalent bond formed during a condensation reaction between amino acids.

Dipeptide

Two amino acids linked together via a peptide bond.

Oligopeptide

A chain of 3-20 amino acids linked by peptide bonds.

Polypeptide

A chain of more than 20 amino acids linked by peptide bonds.

Hydrophilic Amino Acids

Amino acids generally found on the exterior of proteins, interacting with water molecules.

Hydrophobic Amino Acids

Amino acids generally found in the interior of proteins, avoiding water molecules.

Primary Structure

The amino acid sequence of a polypeptide chain.

Secondary Structure

The pleating and coiling of proteins due to hydrogen bonding (alpha-helix and beta-pleated sheet).

Tertiary Structure

The 3D shape of a protein held together by hydrogen bonds, ionic bonds, disulfide bonds, and hydrophobic interactions among R-groups.

Quaternary Structure

The arrangement of two or more polypeptide subunits or a polypeptide conjugated with a prosthetic group.

Disulfide Bonds

Covalent bonds formed between cysteine amino acids, contributing to the tertiary structure of proteins.

Globular Proteins

Soluble, compact, and functional proteins (e.g., insulin).

Fibrous Proteins

Insoluble, long, and strong proteins serving structural roles (e.g., collagen).

Denaturation

The process where a protein loses its shape due to changes in pH or temperature, leading to loss of function.

Nonessential Amino Acids

Amino acids that animals can synthesize under most conditions (11).

Essential Amino Acids

Amino acids that animals cannot synthesize and must obtain through diet (9).

Complete Protein

A protein source that contains all 9 essential amino acids.

Incomplete Protein

A protein source that lacks one or more of the essential amino acids.

Cryo-EM

Cryogenic electron microscopy, a modern imaging technology allowing visualization of single-protein molecules at near-atomic detail.