- activation energy
- amount of energy greater than the energy contained in the reactants, which must be overcome for a reaction to proceed
- adenosine triphosphate (ATP)
- nucleotide containing ribose and an adenine base that is essential in energy transfer
- amino acid
- building block of proteins; characterized by an amino and carboxyl functional groups and a variable side-chain
- anion
- atom with a negative charge
- atom
- smallest unit of an element that retains the unique properties of that element
- atomic number
- number of protons in the nucleus of an atom
- base
- compound that accepts hydrogen ions (H+) in solution
- bond
- electrical force linking atoms
- buffer
- solution containing a weak acid or a weak base that opposes wide fluctuations in the pH of body fluids
- carbohydrate
- class of organic compounds built from sugars, molecules containing carbon, hydrogen, and oxygen in a 1-2-1 ratio
- catalyst
- substance that increases the rate of a chemical reaction without itself being changed in the process
- cation
- atom with a positive charge
- chemical energy
- form of energy that is absorbed as chemical bonds form, stored as they are maintained, and released as they are broken
- colloid
- liquid mixture in which the solute particles consist of clumps of molecules large enough to scatter light
- compound
- substance composed of two or more different elements joined by chemical bonds
- concentration
- number of particles within a given space
- covalent bond
- chemical bond in which two atoms share electrons, thereby completing their valence shells
- decomposition reaction
- type of catabolic reaction in which one or more bonds within a larger molecule are broken, resulting in the release of smaller molecules or atoms
- denaturation
- change in the structure of a molecule through physical or chemical means
- deoxyribonucleic acid (DNA)
- deoxyribose-containing nucleotide that stores genetic information
- disaccharide
- pair of carbohydrate monomers bonded by dehydration synthesis via a glycosidic bond
- disulfide bond
- covalent bond formed within a polypeptide between sulfide groups of sulfur-containing amino acids, for example, cysteine
- electron
- subatomic particle having a negative charge and nearly no mass; found orbiting the atom’s nucleus
- electron shell
- area of space a given distance from an atom’s nucleus in which electrons are grouped
- element
- substance that cannot be created or broken down by ordinary chemical means
- enzyme
- protein or RNA that catalyzes chemical reactions
- exchange reaction
- type of chemical reaction in which bonds are both formed and broken, resulting in the transfer of components
- functional group
- group of atoms linked by strong covalent bonds that tends to behave as a distinct unit in chemical reactions with other atoms
- hydrogen bond
- dipole-dipole bond in which a hydrogen atom covalently bonded to an electronegative atom is weakly attracted to a second electronegative atom
- inorganic compound
- substance that does not contain both carbon and hydrogen
- ion
- atom with an overall positive or negative charge
- ionic bond
- attraction between an anion and a cation
- isotope
- one of the variations of an element in which the number of neutrons differ from each other
- kinetic energy
- energy that matter possesses because of its motion
- lipid
- class of nonpolar organic compounds built from hydrocarbons and distinguished by the fact that they are not soluble in water
- macromolecule
- large molecule formed by covalent bonding
- mass number
- sum of the number of protons and neutrons in the nucleus of an atom
- matter
- physical substance; that which occupies space and has mass
- molecule
- two or more atoms covalently bonded together
- monosaccharide
- monomer of carbohydrate; also known as a simple sugar
- neutron
- heavy subatomic particle having no electrical charge and found in the atom’s nucleus
- nucleotide
- class of organic compounds composed of one or more phosphate groups, a pentose sugar, and a base
- organic compound
- substance that contains both carbon and hydrogen
- peptide bond
- covalent bond formed by dehydration synthesis between two amino acids
- periodic table of the elements
- arrangement of the elements in a table according to their atomic number; elements having similar properties because of their electron arrangements compose columns in the table, while elements having the same number of valence shells compose rows in the table
- pH
- negative logarithm of the hydrogen ion (H+) concentration of a solution
- phospholipid
- a lipid compound in which a phosphate group is combined with a diglyceride
- phosphorylation
- addition of one or more phosphate groups to an organic compound
- polar molecule
- molecule with regions that have opposite charges resulting from uneven numbers of electrons in the nuclei of the atoms participating in the covalent bond
- polysaccharide
- compound consisting of more than two carbohydrate monomers bonded by dehydration synthesis via glycosidic bonds
- potential energy
- stored energy matter possesses because of the positioning or structure of its components
- product
- one or more substances produced by a chemical reaction
- prostaglandin
- lipid compound derived from fatty acid chains and important in regulating several body processes
- protein
- class of organic compounds that are composed of many amino acids linked together by peptide bonds
- proton
- heavy subatomic particle having a positive charge and found in the atom’s nucleus
- purine
- nitrogen-containing base with a double ring structure; adenine and guanine
- pyrimidine
- nitrogen-containing base with a single ring structure; cytosine, thiamine, and uracil
- radioactive isotope
- unstable, heavy isotope that gives off subatomic particles, or electromagnetic energy, as it decays; also called radioisotopes
- reactant
- one or more substances that enter into the reaction
- ribonucleic acid (RNA)
- ribose-containing nucleotide that helps manifest the genetic code as protein
- solution
- homogeneous liquid mixture in which a solute is dissolved into molecules within a solvent
- steroid
- (also, sterol) lipid compound composed of four hydrocarbon rings bonded to a variety of other atoms and molecules
- substrate
- reactant in an enzymatic reaction
- suspension
- liquid mixture in which particles distributed in the liquid settle out over time
- synthesis reaction
- type of anabolic reaction in which two or more atoms or molecules bond, resulting in the formation of a larger molecule
- triglyceride
- lipid compound composed of a glycerol molecule bonded with three fatty acid chains
- valence shell
- outermost electron shell of an atom
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