Amino acids, proteins and DNA (A-level only) key terms

Amino acid

A molecule containing both an amine group (-NH2) and a carboxylic acid group (-COOH).

Peptide bond

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

Zwitterion

A molecule that has both positive and negative charges but is overall neutral.

Amino acid

Organic compounds that serve as the building blocks of proteins.

Peptide Bond

A covalent bond formed between two amino acids through a condensation reaction, resulting in the release of water.

Condensation Reaction

A chemical reaction where two molecules combine to form a larger molecule with the elimination of a small molecule, typically water.

Peptide bond

A covalent bond formed between two amino acids during protein synthesis.

Protease

An enzyme that catalyzes the hydrolysis of peptide bonds in proteins.

Nucleotide

The basic building block of DNA, consisting of a phosphate group, deoxyribose sugar, and a nitrogenous base.

Deoxyribose

A five-carbon sugar that is a component of DNA nucleotides.

Condensation Reaction

A chemical reaction in which two molecules combine to form a larger molecule, with the loss of a small molecule, typically water.

Phosphodiester Bond

A covalent bond that connects the phosphate group of one nucleotide to the sugar of another nucleotide in the DNA backbone.

Hydrogen bond

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Complementary base pairing

The specific pairing of nitrogenous bases in DNA, where adenine pairs with thymine and guanine pairs with cytosine.

Complementary base pairing

The specific pairing of nitrogenous bases in DNA, where adenine pairs with thymine and cytosine pairs with guanine.

Double helix

The twisted ladder shape of DNA formed by two strands of nucleotides running in opposite directions.