Proteins and Their Structure

These flashcards cover key vocabulary terms related to proteins, their structures, and functions.

Protein

Large, complex molecules made from amino acids that play essential roles in the structure and metabolism of living organisms.

Amino acids

The basic units or monomers that join via peptide bonds to form proteins.

Peptide bond

The bond formed between the amino group of one amino acid and the carboxyl group of another amino acid during protein synthesis.

Primary Structure

The linear sequence of amino acids in a polypeptide chain, which determines the properties and shape of a protein.

Secondary Structure

The folding or twisting of amino acids in a polypeptide due to hydrogen bonding, resulting in structures like alpha helices and beta pleated sheets.

α helix

A common secondary structure in proteins where the polypeptide chains coil into a spiral shape held together by hydrogen bonds.

β pleated sheet

A secondary structure formed by adjacent sections of polypeptide chains lying parallel or antiparallel to each other, stabilized by hydrogen bonds.

Tertiary Structure

The three-dimensional shape of a protein formed by the folding of alpha helices and beta sheets, involving various types of bonding between R groups.

Quaternary Structure

The arrangement and interaction of multiple polypeptide chains in a protein, forming a functional molecule.

Denaturation

The process by which the structure of a protein is disrupted due to changes in temperature, pH, or chemicals, leading to loss of biological activity.

Globular Proteins

Proteins that have complex tertiary and quaternary structures, are usually soluble in water, and are metabolically active.

Fibrous Proteins

Proteins that form long fibers or sheets, usually insoluble in water and serve structural roles.

Collagen

The most abundant fibrous protein that provides strength and structure to connective tissues such as skin, bones, and tendons.

Haemoglobin

A globular protein responsible for carrying oxygen in red blood cells, consisting of four polypeptide chains and a non-protein prosthetic group (haem).

Hydrophobic interactions

Interactions that occur between non-polar R groups in proteins, driving them away from water in an aqueous environment, thus stabilizing protein structure.

Hydrogen bond

A weak bond that forms between hydrogen atoms and electronegative atoms (like oxygen or nitrogen), playing key roles in maintaining protein structure.

Ionic bonds

Electrostatic attractions between oppositely charged R groups in proteins, important for stabilizing complex structures.

Van der Waals forces

Weak attractions that occur between molecules or parts of molecules that are in close proximity, contributing to protein stability.

Prosthetic group

A non-polypeptide unit that is tightly and permanently attached to a protein, contributing to its function (e.g., haem in haemoglobin).