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Portion of ATP and ADP that is composed of the base adenine and the sugar ribose.

ADP (adenosine diphosphate) amino acid

Nucleotide with two phosphate groups that can accept another phosphate group and become ATP.

ATP (adenosine triphosphate)

Nucleotide with three phosphate groups. The breakdown of ATP into ADP_P makes energy available for energy-requiring processes in cells.


Organic molecule (macromolecule as a protein or nucleic acid) in living organisms.


Class of organic compounds that includes monosaccharides, disaccharides, and polysaccharides.


Polysaccharide that is the major complex carbohydrate in plant cell walls.

chaperone protein

Molecule that interacts with a protein so that it folds into its proper shape.


Strong but flexible nitrogenous polysaccharide found in the exoskeleton of arthropods and in the cell walls of fungi.


Nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound.

complementary base pairing

Hydrogen bonding between particular purines and pyrimidines in DNA.

dehydration reaction

Chemical reaction resulting in a covalent bond with the accompanying loss of a water molecule.


Loss of an enzyme's normal shape so that it no longer functions; caused by a less than optimal pH and temperature.


Pentose sugar found in DNA.


Sugar that contains two units of a monosaccharide; e.g., maltose.

DNA (deoxyribonucleic acid)

Nucleic acid polymer produced from covalent bonding of nucleotide monomers that contain the sugar deoxyribose; the genetic material of nearly all organisms.


Organic catalyst, usually a protein, that speeds a reaction in cells due to its particular shape.


Organic molecule that contains glycerol and fatty acids and is found in adipose tissue of vertebrates.

fatty acid

Molecule that contains a hydrocarbon chain and ends with an acid group.

fibrous protein

A protein that has only a secondary structure; generally insoluble; includes collagens, elastins, and keratins.

functional group

Specific cluster of atoms attached to the carbon skeleton of organic molecules that enters into reactions and behaves in a predictable way.

globular protein

Most of the proteins in the body; soluble in water or salt solution; includes albumins, globulins, histones.


Six-carbon sugar that organisms degrade as a source of energy during cellular respiration.


Three-carbon carbohydrate with three hydroxyl groups attached; a component of fats and oils.


Storage polysaccharide found in animals; composed of glucose molecules joined in a linear fashion but having numerous branches.


Iron containing respiratory pigment occurring in vertebrate red blood cells and in the blood plasma of some invertebrates.


Six-carbon sugar.

hydrolysis reaction

Splitting of a bond by the addition of water, with the H_ going to one molecule and the OH_ going to the other.


Type of molecule that interacts with water by dissolving in water and/or by forming hydrogen bonds with water molecules.


Type of molecule that does not interact with water because it is nonpolar.

inorganic chemistry

Branch of science which deals with compounds that are not unique to the plant or animal worlds.


Molecules with the same molecular formula but a different structure, and therefore a different shape.


Class of organic compounds that tends to be soluble in nonpolar solvents; includes fats and oils.


Small molecule that is a subunit of a polymer—e.g., glucose is a monomer of starch.


Simple sugar; a carbohydrate that cannot be decomposed by hydrolysis—e.g., glucose.

nucleic acid

Polymer of nucleotides; both DNA and RNA are nucleic acids.


Monomer of DNA and RNA consisting of a 5-carbon sugar bonded to a nitrogenous base and a phosphate group.


Triglyceride, usually of plant origin, that is composed of glycerol and three fatty acids and is liquid in consistency due to many unsaturated bonds in the hydrocarbon chains of the fatty acids.

organic chemistry

Branch of science which deals with organic molecules including those that are unique to living things.

organic molecule

Molecule that always contains carbon and hydrogen, and often contains oxygen as well; organic molecules are associated with living things.


Five-carbon sugar. Deoxyribose is the pentose sugar found in DNA; ribose is the pentose sugar found in RNA.


Two or more amino acids joined together by covalent bonding.

peptide bond

Type of covalent bond that joins two amino acids.


Unique molecule found in bacterial cell walls.


Molecule that forms the bilayer of the cell's membranes; has a polar, hydrophilic head bonded to two nonpolar, hydrophobic tails.


Macromolecule consisting of covalently bonded monomers; for example, a polypeptide is a polymer of monomers called amino acids.

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