Words (or words that have the same definition) The definition is case sensitive (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] (Optional) Caption for Image (Optional) External or Internal Link (Optional) Source for Definition (Eg. "Genetic, Hereditary, DNA ...") (Eg. "Relating to genes or heredity") NaN The infamous double helix Biology, Libretexts CC-BY-SA; Delmar Larsen Word(s) Definition Image Caption Link Source Acetyl-CoA A molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle (Krebs cycle) to be oxidized for energy production. NaN NaN NaN NaN addition polymerization A reaction in which monomers add to one another to produce a polymeric product that contains all the atoms of the starting monomers. NaN NaN NaN NaN addition reactions A reaction in which substituent groups join to hydrocarbon molecules at points of unsaturation—the double or triple bonds. NaN NaN NaN NaN alcohol An organic compound with an OH functional group on an aliphatic carbon atom. NaN NaN NaN NaN aldehyde An organic compound with a carbonyl functional group that has an hydrogen atom attached and either a hydrocarbon group or a second hydrogen atom. NaN NaN NaN NaN alkaloid A nitrogen-containing organic compound obtained from plants that has physiological properties. NaN NaN NaN NaN alkanes (or saturated hydrocarbons) A hydrocarbon with only carbon-to-carbon single bonds and existing as a continuous chain of carbon atoms also bonded to hydrogen atoms NaN NaN NaN NaN alkenes A hydrocarbon with one or more carbon–carbon double bonds. NaN NaN NaN NaN alkyl group A hydrocarbon group derived from an alkane by removal of a hydrogen atom. NaN NaN NaN NaN alkyl halide (or haloalkane) A compound resulting from the replacement of a hydrogen atom of an alkane with a halogen atom. NaN NaN NaN NaN Alkynes A hydrocarbon with a carbon–carbon triple bond. NaN NaN NaN NaN alloy A solid solution of a metal with other substances dissolved in it. NaN NaN NaN NaN alpha particle A type of radioactive emission that is equivalent to a helium atom nucleus. NaN NaN NaN NaN amide An organic compound with a carbonyl group joined to a nitrogen atom from ammonia or an amine. NaN NaN NaN NaN amine An organic compound derived from ammonia by the replacement of one, two, or three of the hydrogens atoms by alkyl or aryl groups. NaN NaN NaN NaN amino group An NH2 unit. NaN NaN NaN NaN amorphous A solid with no regular structure. NaN NaN NaN NaN amphiprotic A substance that can either donate or accept a proton, depending on the circumstances. NaN NaN NaN NaN amylopectin A branched polymer of glucose units found in starch. NaN NaN NaN NaN anabolism Metabolic reactions in which molecules are synthesized. NaN NaN NaN NaN anaerobic metabolism A biochemical process that takes place in the absence of oxygen. NaN NaN NaN NaN anions A negatively charged ion. NaN NaN NaN NaN anomeric carbon The carbon atom that was the carbonyl carbon atom in the straight-chain form of a monosaccharide. NaN NaN NaN NaN anticodon A set of three nucleotides on the tRNA that is complementary to, and pairs with, the codon on the mRNA. NaN NaN NaN NaN antioxidants A substance in foods that acts as a reducing agent. NaN NaN NaN NaN aromatic compound Any compound that contains a benzene ring or has certain benzene-like properties. NaN NaN NaN NaN aromatic hydrocarbons A hydrocarbon with a benzene-like structure. NaN NaN NaN NaN aryl group A group derived from an aromatic hydrocarbon by the removal of a hydrogen atom. NaN NaN NaN NaN atomic bomb A weapon that depends on a nuclear chain reaction to generate immense forces. NaN NaN NaN NaN atomic mass A weighted average of the masses of all the element’s naturally occurring isotopes. NaN NaN NaN NaN atomic mass unit One-twelfth the mass of a 12C atom. NaN NaN NaN NaN atomic radius The approximate size of an atom. NaN NaN NaN NaN autoionization of water The process by which water ionizes into hydronium ions and hydroxide ions as it acts as an acid and a base. NaN NaN NaN NaN Avogadro’s number The value 6.022 × 1023. NaN NaN NaN NaN balanced A property of a chemical equation when there are the same number of atoms of each element in the reactants and products. NaN NaN NaN NaN base A compound that increases the concentration of hydroxide ion (OH−) in aqueous solution. NaN NaN NaN NaN Base (or basic) units A fundamental unit of SI. NaN NaN NaN NaN beta particle A type of radioactive emission that is equivalent to an electron. NaN NaN NaN NaN Bilayers A double layer of lipids arranged so that nonpolar tails are found between an inner surface and outer surface consisting of hydrophilic heads. NaN NaN NaN NaN Bile The yellowish green liquid produced in the liver. NaN NaN NaN NaN biochemistry The chemistry of molecules found in living organisms. NaN NaN NaN NaN boiling point The temperature at which a substance goes from a liquid to a gas (or from a gas to a liquid). NaN NaN NaN NaN boiling point elevation The raising of the boiling point of a solution versus the pure solvent. NaN NaN NaN NaN bond length The distance between two nuclei in a covalent bond. NaN NaN NaN NaN Boyle’s law The gas law that relates pressure and volume. NaN NaN NaN NaN Brønsted-Lowry base A compound that accepts a hydrogen ion (H+) in a reaction; a proton acceptor. NaN NaN NaN NaN buffer A solution that resists dramatic changes in pH. NaN NaN NaN NaN calorie A unit of energy widely used in the health professions and everyday life. NaN NaN NaN NaN capacity The amount of strong acid or base a buffer can counteract. NaN NaN NaN NaN carbohydrates A compound composed of carbon, hydrogen, and oxygen atoms that is a polyhydroxy aldehyde or ketone or a compound that can be broken down to form such a compound. It is one of the three main components of the human diet. NaN NaN NaN NaN carboxyl group A functional group that contains a carbon–oxygen bond and an OH group also attached to the same carbon atom. NaN NaN NaN NaN carboxylic acids An organic compound that has a carboxyl functional group. NaN NaN NaN NaN cations A positively charged ion. NaN NaN NaN NaN cerebrosides A sphingolipid that contains a fatty acid unit, a sphingosine unit, and galactose or glucose. NaN NaN NaN NaN chain reaction An exponential growth in a process. NaN NaN NaN NaN Charles’s law The gas law that relates volume and absolute temperature. NaN NaN NaN NaN chemical bond A very strong attraction between two atoms. NaN NaN NaN NaN chemical equilibrium (or equilibrium) The condition in which the extent of a chemical reaction does not change any further. NaN NaN NaN NaN chemical formula A concise list of the elements in a compound and the ratios of these elements. NaN NaN NaN NaN Chemical properties A characteristic that describes how matter changes its chemical structure or composition. NaN NaN NaN NaN chemical reaction A representation of a chemical change. NaN NaN NaN NaN chemical symbol A one- or two-letter abbreviation for an element. NaN NaN NaN NaN chiral carbon A carbon atom that has four different groups attached to it. NaN NaN NaN NaN Cholesterol A steroid that is found in mammals. NaN NaN NaN NaN cis-trans isomers (or geometric isomers) Isomers that have different configurations because of the presence of a rigid structure such as a double bond or ring. NaN NaN NaN NaN citric acid cycle, Krebs cycle, tricarboxylic acid cycle, TCA cycle A cyclic sequence of reactions that brings about the oxidation of a two-C unit to carbon dioxide and water. NaN NaN NaN NaN codon A set of three nucleotides on the mRNA that specifies a particular amino acid. NaN NaN NaN NaN coefficient A number that gives the number of molecules of a substance in a balanced chemical equation. NaN NaN NaN NaN coenzymes A cofactor that is an organic molecule. NaN NaN NaN NaN colligative properties A characteristic of solutions that depends only on the number of dissolved particles. NaN NaN NaN NaN combination (composition) reaction A chemical reaction that makes a single substance from two or more reactants. NaN NaN NaN NaN combined gas law The gas law that relates pressure, volume, and absolute temperature. NaN NaN NaN NaN combustion reaction A chemical reaction in which a substance combines with molecular oxygen to make oxygen-containing compounds of other elements in the reaction. NaN NaN NaN NaN competitive inhibitor A compound that resembles a particular substrate and competes with the substrate for binding at the active site of an enzyme to slow the rate of the reaction. NaN NaN NaN NaN complementary bases Specific base pairings in the DNA double helix. NaN NaN NaN NaN compound A substance that can be broken down into chemically simpler components. NaN NaN NaN NaN concentration How much solute is dissolved in a certain amount of solvent. NaN NaN NaN NaN condensed structural formulas An organic chemical formula that shows the hydrogen atoms (or other atoms or groups) right next to the carbon atoms to which they are attached. NaN NaN NaN NaN conversion factor A fraction that has equivalent quantities in the numerator and the denominator but expressed in different units. NaN NaN NaN NaN core electrons An electron in a lower-numbered shell of an atom. NaN NaN NaN NaN covalent network bonding A type of interaction in which all the atoms in a sample are covalently bonded to other atoms. NaN NaN NaN NaN curie (Ci) A unit of radioactivity equal to 3.7 × 1010 decays per second. NaN NaN NaN NaN cyclic hydrocarbons A hydrocarbon with a ring of carbon atoms. NaN NaN NaN NaN cycloalkanes A cyclic hydrocarbon with only single bonds. NaN NaN NaN NaN cytochromes A protein that contains an iron porphyrin in which iron can alternate between Fe(II) and Fe(III). NaN NaN NaN NaN cytoplasm Everything between the cell membrane and the nuclear membrane. NaN NaN NaN NaN decomposition reaction A chemical reaction in which a single substance is converted into two or more products. NaN NaN NaN NaN Denaturation Any change in the three-dimensional structure of a macromolecule that renders it incapable of performing its assigned function. NaN NaN NaN NaN Density The mass of an object divided by its volume. NaN NaN NaN NaN Derived units A combinations of the SI base units. NaN NaN NaN NaN diatomic molecules A two-atom grouping that behaves as a single chemical entity. NaN NaN NaN NaN digestion The breakdown of food molecules by hydrolysis reactions into the individual monomer units in the mouth, stomach, and small intestine. NaN NaN NaN NaN dipole-dipole interaction An attraction between polar molecules. NaN NaN NaN NaN Dispersion forces A force caused by the instantaneous imbalance of electrons about a molecule. NaN NaN NaN NaN dispersion forces (or London forces) A force caused by the instantaneous imbalance of electrons about a molecule. NaN NaN NaN NaN dissociation The process of cations and anions of an ionic solute separating when the solute dissolves. NaN NaN NaN NaN Disulfide linkages A covalent bond that forms by the oxidation and linkage of two sulfur atoms from the side chains of two cysteine residues. NaN NaN NaN NaN double bond Two pairs of electrons being shared by two atoms in a molecule. NaN NaN NaN NaN electron A subatomic particle with a negative electric charge. NaN NaN NaN NaN electron configuration A shorthand description of the arrangement of electrons in an atom. NaN NaN NaN NaN electron transport chain (or respiratory chain) An organized sequence of oxidation-reduction reactions that ultimately transports electrons to oxygen, reducing it to water. NaN NaN NaN NaN electronegativity A relative measure of how strongly an atom attracts electrons when it forms a covalent bond. NaN NaN NaN NaN emulsion A dispersion of two liquids that do not normally mix. NaN NaN NaN NaN enantiomers Stereoisomers that are nonsuperimposable mirror images of each other. NaN NaN NaN NaN endothermic A process that absorbs energy. NaN NaN NaN NaN Energy The ability to do work. NaN NaN NaN NaN equivalents (Eq) One mole of charge (either positive or negative). NaN NaN NaN NaN essential fatty acids A fatty acid that must be obtained from the diet because it cannot be synthesized by the human body. NaN NaN NaN NaN ester An organic compound derived from a carboxylic acid and an alcohol in which the OH of the acid is replaced by an OR group. NaN NaN NaN NaN esterification The formation of an ester from a carboxylic acid and an alcohol. NaN NaN NaN NaN ether An organic compound that has an oxygen atom between two hydrocarbon groups. NaN NaN NaN NaN Exact numbers A number that is defined or counted. NaN NaN NaN NaN exothermic A process that gives off energy. NaN NaN NaN NaN fats A compound, composed largely of hydrocarbon chains, that supplies energy for the body. NaN NaN NaN NaN Feedback inhibition A normal biochemical process that makes use of noncompetitive inhibitors to control some enzymatic activity. NaN NaN NaN NaN fibrous proteins A protein that is elongated or fiberlike and insoluble in water. NaN NaN NaN NaN formula mass The sum of the masses of the elements in the formula of an ionic compound. NaN NaN NaN NaN formula unit A set of oppositely charged ions that compose an ionic compound. NaN NaN NaN NaN freezing point depression The lowering of the freezing point of a solution versus the pure solvent. NaN NaN NaN NaN functional group, functional groups A structural arrangement of atoms and/or bonds that imparts a wide range of important properties to organic compounds. NaN NaN NaN NaN Fusion A nuclear process in which small nuclei are combined into larger nuclei, releasing energy. NaN NaN NaN NaN galactosemia A genetic disease caused by the absence of one of the enzymes needed to convert galactose to glucose. NaN NaN NaN NaN gamma rays A type of radioactive emission that is a very energetic form of electromagnetic radiation. NaN NaN NaN NaN gangliosides A sphingolipid that contains a fatty acid unit, a sphingosine unit, and a complex oligosaccharide. NaN NaN NaN NaN gas law A simple mathematical formula that relates two or more properties of a gas. NaN NaN NaN NaN Gastric juice A mixture of water, inorganic ions, hydrochloric acid, and various enzymes and proteins found in the stomach. NaN NaN NaN NaN Geiger counter An electrical device that detects radioactivity. NaN NaN NaN NaN genes The basic unit of heredity. NaN NaN NaN NaN genetic code The identification of each group of three nucleotides and its particular amino acid. NaN NaN NaN NaN genetic diseases A hereditary condition caused by an altered DNA sequence. NaN NaN NaN NaN Globular proteins A protein that is generally spherical in structure and soluble in water. NaN NaN NaN NaN glycols An alcohol with two OH functional groups. NaN NaN NaN NaN glycolysis The metabolic pathway in which glucose is broken down to two molecules of pyruvate with the corresponding production of ATP. NaN NaN NaN NaN glycosidic linkage The carbon–oxygen-carbon linkage between monosaccharide units in more complex carbohydrates, such as disaccharides or polysaccharides. NaN NaN NaN NaN groups (or families) A column of elements on the periodic table. NaN NaN NaN NaN half reactions A chemical reaction that shows only oxidation or reduction. NaN NaN NaN NaN half-life The amount of time it takes for one-half of a radioactive isotope to decay. NaN NaN NaN NaN halogenated hydrocarbons A hydrocarbon in which one or more hydrogen atoms has been replaced by a halogen atom. NaN NaN NaN NaN halogenation A reaction in which a halogen reacts at a carbon-to-carbon double or triple bond to add halogen atoms to carbon atoms. NaN NaN NaN NaN heat The transfer of energy from one part of the universe to another due to temperature differences. NaN NaN NaN NaN heat of vaporization The amount of heat per gram or per mole required for a phase change that occurs at the boiling point. NaN NaN NaN NaN heterocyclic compounds A cyclic compound in which one or more atoms in the ring is an element other than a carbon atom. NaN NaN NaN NaN homogeneous mixtures, homogeneous mixture, homogeneous solution A mixture that acts as a single substance so that it is not obvious that two or more substances are present. NaN NaN NaN NaN homologous series Any family of compounds in which adjacent members differ from each other by a definite factor. NaN NaN NaN NaN hydration Solvation by water molecules. NaN NaN NaN NaN Hydrogen bonding Bonding between a highly electronegative oxygen atom or nitrogen atom and a hydrogen atom attached to another oxygen atom or nitrogen atom. NaN NaN NaN NaN hydrogenation A reaction in which hydrogen gas reacts at a carbon-to-carbon double or triple bond or a carbon-to-oxygen double bond to add hydrogen atoms to carbon atoms. NaN NaN NaN NaN hydrolysis The reaction of a substance with water. NaN NaN NaN NaN ideal gas law The gas law that relates volume, pressure, temperature, and amount of a gas. NaN NaN NaN NaN ideal gas law constant The constant the appears in the ideal gas law. NaN NaN NaN NaN immiscible Liquids that do not dissolve in each other. NaN NaN NaN NaN induced-fit model A model that says an enzyme can undergo a conformational change when it binds substrate molecules. NaN NaN NaN NaN inner transition metals An element in the two rows beneath the main body on the periodic table. Such metals are also called the lanthanide and actinide elements. NaN NaN NaN NaN inorganic chemistry The study of the chemistry of all other elements. NaN NaN NaN NaN intermolecular interactions A force of attraction between different molecules. NaN NaN NaN NaN Ionic bonding Bonding that results from electrostatic attractions between positively and negatively charged groups. NaN NaN NaN NaN ionic compounds A compound formed with an ionic bond. NaN NaN NaN NaN ionic interactions An attraction due to ions of opposite charges. NaN NaN NaN NaN irreversible inhibitor A substance that inactivates an enzyme by bonding covalently to a specific group at the active site. NaN NaN NaN NaN isoelectric point The pH at which a given amino acid exists in solution as a zwitterion. NaN NaN NaN NaN isomers Compounds having the same molecular formula but different structural formulas and properties. NaN NaN NaN NaN isothermal A process that occurs at constant temperature. NaN NaN NaN NaN isotopes Atoms of the same element that have different numbers of neutrons. NaN NaN NaN NaN IUPAC System of Nomenclature A systematic way of naming chemical substances so that each has a unique name. NaN NaN NaN NaN joule The SI unit of energy, work, and heat. NaN NaN NaN NaN ketogenic amino acids An amino acid that is converted to acetoacetyl-CoA or acetyl-CoA, which can be used for the synthesis of ketone bodies but not glucose. NaN NaN NaN NaN ketone An organic compound whose molecules have a carbonyl functional group between two hydrocarbon groups. NaN NaN NaN NaN ketoses A monosaccharide that contains a ketone functional group on the second carbon atom. NaN NaN NaN NaN kinetic theory of gases The fundamental theory of the behavior of gases. NaN NaN NaN NaN L sugars A sugar whose Fischer projection terminates in the same configuration as L-glyceraldehyde. NaN NaN NaN NaN lattice energy The strength of interactions between atoms that make ionic bonds. NaN NaN NaN NaN law A general statement that explains a large number of observations. NaN NaN NaN NaN law of conservation of matter In any given system that is closed to the transfer of matter (in and out), the amount of matter in the system stays constant. NaN NaN NaN NaN Lewis diagrams A representation that shows valence electrons as dots around the chemical symbol of an atom (also called Lewis electron dot diagrams). NaN NaN NaN NaN line-angle formula An organic chemical formula in which carbon atoms are implied at the corners and ends of lines. Each carbon atom is understood to be attached to enough hydrogen atoms to give each carbon atom four bonds. NaN NaN NaN NaN lipids A compound isolated from body tissues that is more soluble in organic solvents than in water. NaN NaN NaN NaN lock-and-key model A model that portrays an enzyme as conformationally rigid and able to bond only to a substrate or substrates that exactly fit the active site. NaN NaN NaN NaN mass number The sum of the numbers of protons and neutrons in a nucleus of an atom. NaN NaN NaN NaN mass-mass calculations A stoichiometry calculation converting between the mass of one substance and the mass of a different substance in a chemical reaction. NaN NaN NaN NaN mass/mass percent A concentration unit that relates the mass of the solute to the mass of the solution. NaN NaN NaN NaN mass/volume percent A concentration unit that relates the mass of the solute to the volume of the solution. NaN NaN NaN NaN Matter Anything that has mass and takes up space. NaN NaN NaN NaN metabolic pathway A series of biochemical reactions by which an organism converts a given reactant to a specific end product. NaN NaN NaN NaN microscopic A view of the universe in which one is working with a few atoms or molecules at a time. NaN NaN NaN NaN mitochondria Small, oval organelles with double membranes; the “power plants” of a cell. NaN NaN NaN NaN modern atomic theory The fundamental concept that all elements are composed of atoms. NaN NaN NaN NaN molar mass The mass of 1 mol of atoms or molecules. NaN NaN NaN NaN Molarity Number of moles of solute per liter of solution. NaN NaN NaN NaN mole-mass calculations A stoichiometry calculation converting between masses and moles of different substances in a chemical reaction. NaN NaN NaN NaN mole-mass conversion The conversion from moles of material to the mass of that same material. NaN NaN NaN NaN molecular formulas A chemical formula for a covalent compound. NaN NaN NaN NaN molecular mass The mass of a molecule, which is the sum of the masses of its atoms. NaN NaN NaN NaN molecule A discrete group of atoms connected by covalent bonds. NaN NaN NaN NaN mutagens A chemical or physical agent that cause mutations. NaN NaN NaN NaN mutarotation The ongoing interconversion between anomeric forms of a monosaccharide to form an equilibrium mixture. NaN NaN NaN NaN mutation Any chemical or physical change that alters the nucleotide sequence in DNA. NaN NaN NaN NaN neutralization The reaction of acid and base to make water and a salt. NaN NaN NaN NaN neutron A subatomic particle with no electric charge. NaN NaN NaN NaN nomenclature The systematic naming of chemical compounds. NaN NaN NaN NaN nonbonding pairs (or lone pairs) Electron pair that does not participate in covalent bonds. NaN NaN NaN NaN noncompetitive inhibitor A compound that can combine with either the free enzyme or the enzyme-substrate complex at a site distinct from the active site to slow the rate of the reaction. NaN NaN NaN NaN nonelectrolytes A compound that does not ionize at all when it dissolves. NaN NaN NaN NaN nonpolar covalent bond A covalent bond with a balanced electron distribution across the bond. NaN NaN NaN NaN Nuclear energy The controlled harvesting of energy from fission reactions. NaN NaN NaN NaN nuclear reactor An apparatus designed to carefully control the progress of a nuclear reaction and extract the resulting energy for useful purposes. NaN NaN NaN NaN nucleotides A monomer unit that is linked together to form nucleic acids. NaN NaN NaN NaN nucleus The central part of an atom that contains protons and neutrons. NaN NaN NaN NaN octet rule The idea that atoms tend to have eight electrons in their valence shell. NaN NaN NaN NaN oil A triglyceride that is a liquid at room temperature. NaN NaN NaN NaN optimum pH The pH at which a particular enzyme exhibits maximum activity. NaN NaN NaN NaN Organic chemistry The study of the chemistry of carbon compounds. NaN NaN NaN NaN organic compound A compound containing carbon atoms. NaN NaN NaN NaN Osmolarity A way of reporting the total number of particles in a solution to determine the osmotic pressure. NaN NaN NaN NaN osmotic pressure The tendency for solvent molecules to move from the more dilute solution to the more concentrated solution until the concentrations of the two solutions are equal. NaN NaN NaN NaN oxidative deamination A reaction in which glutamate loses its amino group as an ammonium ion and is oxidized back to α-ketoglutarate. NaN NaN NaN NaN oxidative phosphorylation The process that links ATP synthesis to the operation of the electron transport chain. NaN NaN NaN NaN oxidizing agent A species that causes oxidation, which is itself reduced. NaN NaN NaN NaN parts per billion (ppb) The mass of a solute compared to the mass of a solution times 1,000,000,000. NaN NaN NaN NaN peptide bond The amide bond joining two amino acid units in a peptide or protein. NaN NaN NaN NaN period A row of elements on the periodic table. NaN NaN NaN NaN periodic table A chart of elements that groups the elements by some of their properties. NaN NaN NaN NaN peripheral proteins A protein that is more loosely associated with the membrane surface. NaN NaN NaN NaN pH scale A logarithmic scale that relates the concentration of the hydrogen ion in solution. NaN NaN NaN NaN phase A form of matter that has the same physical properties throughout. NaN NaN NaN NaN phase change A physical process in which a substance goes from one phase to another. NaN NaN NaN NaN phases A certain form of matter that includes a specific set of physical properties. NaN NaN NaN NaN phenols An aromatic compound with an OH group attached directly to a benzene ring. NaN NaN NaN NaN photosynthesis The process by which plants use solar energy to convert carbon dioxide and water to glucose. NaN NaN NaN NaN point mutations A change in which one nucleotide is substituted, added, or deleted. NaN NaN NaN NaN polar A molecule with a net unequal distribution of electrons in its covalent bonds. NaN NaN NaN NaN polyamide A condensation polymer in which the monomer units are joined by an amide linkage. NaN NaN NaN NaN polyatomic ions An ion with more than one atom. NaN NaN NaN NaN polycyclic aromatic hydrocarbons (PAHs) An aromatic hydrocarbon consisting of fused benzene rings sharing a common side. NaN NaN NaN NaN polymers A giant molecule formed by the combination of monomers in a repeating manner. NaN NaN NaN NaN polypeptides A chain of about 50 or more amino acids. NaN NaN NaN NaN polysaccharides A carbohydrate containing many monosaccharide units. NaN NaN NaN NaN polyunsaturated fatty acids A fatty acid that has two or more carbon-to-carbon double bonds. NaN NaN NaN NaN power The exponent in a number expressed in scientific notation. NaN NaN NaN NaN pressure Force divided by area. NaN NaN NaN NaN primary (1°) alcohol A compound with an OH group on a carbonatom that is attached to only one other carbon atom. NaN NaN NaN NaN primary structure The sequence of amino acids in a polypeptide chain or protein. NaN NaN NaN NaN products A substance on the right side of the arrow in a chemical equation. NaN NaN NaN NaN Proteins A compound of high molar mass consisting largely or entirely of amino acids linked together. NaN NaN NaN NaN proton A subatomic particle with a positive charge. NaN NaN NaN NaN purines A heterocyclic amine consisting of a pyrimidine ring fused to a five-member ring with two nitrogen atoms. NaN NaN NaN NaN quantized Having a fixed value. NaN NaN NaN NaN quantum mechanics The modern theory of electron behavior. NaN NaN NaN NaN quaternary structure The arrangement of multiple subunits in a protein. NaN NaN NaN NaN rad A unit of radioactive exposure equal to 0.01 J/g of tissue. NaN NaN NaN NaN radioactivity Emanations of particles and radiation from atomic nuclei. NaN NaN NaN NaN reducing sugar Any carbohydrate capable of reducing a mild oxidizing agent, such as Tollens’ or Benedict’s reagents, without first undergoing hydrolysis. NaN NaN NaN NaN rem A unit of radioactive exposure that includes a factor to account for the type of radioactivity. NaN NaN NaN NaN replication The process in which the DNA in a dividing cell is copied. NaN NaN NaN NaN respiration The process by which cells oxidize organic molecules in the presence of gaseous oxygen to produce carbon dioxide, water, and energy in the form of ATP. NaN NaN NaN NaN retroviruses An RNA virus that directs the synthesis of a DNA copy in the host cell. NaN NaN NaN NaN ribonucleic acid, RNA The nucleic acid responsible for using the genetic information encoded in DNA. NaN NaN NaN NaN ribosomes A cellular substructure where proteins are synthesized. NaN NaN NaN NaN round The process of assessing the final significant figure of a quantity to determine if it should be kept or moved higher. NaN NaN NaN NaN saponification The hydrolysis of fats and oils in the presence of a base to make soap. NaN NaN NaN NaN science The process by which we learn about the natural universe by observing, testing, and then generating models that explain our observations. NaN NaN NaN NaN scientific method An organized procedure for learning answers to questions. NaN NaN NaN NaN secondary (2°) alcohol A compound with an OH group on a carbon atom that is attached to two other carbon atoms. NaN NaN NaN NaN secondary structure The fixed arrangement of the polypeptide backbone. NaN NaN NaN NaN semimetals, metalloids An element whose properties are intermediate between metals and nonmetals. NaN NaN NaN NaN shells A grouping of electrons within an atom. NaN NaN NaN NaN significant figures All the digits of a measured quantity known with certainty and the first uncertain, or estimated, digit. NaN NaN NaN NaN single bond A covalent bond formed by a single pair of electrons. NaN NaN NaN NaN solubility The limit of how much solute can be dissolved in a given amount of solvent. NaN NaN NaN NaN solute The minor component of a solution. NaN NaN NaN NaN solution Another name for a homogeneous mixture. NaN NaN NaN NaN specific heat A proportionality constant that relates heat to a temperature change. NaN NaN NaN NaN Sphingolipids A lipid that contains the unsaturated amino alcohol sphingosine. NaN NaN NaN NaN Sphingomyelins A sphingolipid that contains a fatty acid unit, a phosphoric acid unit, a sphingosine unit, and a choline unit. NaN NaN NaN NaN spontaneous fission, fission The breaking apart of an atomic nucleus into smaller nuclei. NaN NaN NaN NaN standard temperature and pressure, STP 273 K (0°C) and 1.00 atm pressure. NaN NaN NaN NaN steroids A lipid with a four-fused-ring structure. NaN NaN NaN NaN Stock system The system of indicating a cation’s charge with roman numerals. NaN NaN NaN NaN stoichiometry The study of the numerical relationships between the reactants and the products in a balanced chemical equation. NaN NaN NaN NaN strong acid An acid that is 100% ionized in aqueous solution. NaN NaN NaN NaN strong base A base that is 100% ionized in aqueous solution. NaN NaN NaN NaN structural formula A chemical formula that shows how the atoms of a molecule are attached to one another. NaN NaN NaN NaN subshells A grouping of electrons within a shell. NaN NaN NaN NaN substrate-level phosphorylation The synthesis of ATP by the direct transfer of a phosphate group from a metabolite to ADP. NaN NaN NaN NaN substrates A compound on which an enzyme acts. NaN NaN NaN NaN tertiary (3°) alcohol A compound with an OH group on a carbon atom that is attached to three other carbon atoms. NaN NaN NaN NaN tertiary (3°) amine A compound that has three alkyl or aryl groups on the nitrogen atom. NaN NaN NaN NaN tertiary structure The unique three-dimensional shape of a polypeptide chain as a whole. NaN NaN NaN NaN theory A general statement that describes a large set of observations and data. NaN NaN NaN NaN Thiols A compound with an SH functional group. NaN NaN NaN NaN torr Another name for millimeters of mercury. NaN NaN NaN NaN tracer A substance that can be used to follow the pathway of that substance through some structure. NaN NaN NaN NaN transamination An exchange of functional groups between any amino acid and an α-keto acid. NaN NaN NaN NaN transcription The process in which RNA is synthesized from a DNA template. NaN NaN NaN NaN translation The process in which the information encoded in mRNA is used to direct the sequencing of amino acids to synthesize a protein. NaN NaN NaN NaN triglycerides An ester composed of three fatty acid units linked to glycerol and found in fats and oils. NaN NaN NaN NaN triple bonds Three pairs of electrons being shared by two atoms in a molecule. NaN NaN NaN NaN unit The scale of measurement for a quantity. NaN NaN NaN NaN unsaturated A solution whose solute is less than its solubility limit. NaN NaN NaN NaN unsaturated hydrocarbons An alkene or alkyne having one or more multiple (double or triple) bonds between carbon atoms. NaN NaN NaN NaN valence shell electron pair repulsion, VSEPR The general concept that estimates the shape of a simple molecule. NaN NaN NaN NaN vapor pressure The pressure of a vapor that is in equilibrium with its liquid phase. NaN NaN NaN NaN vapor pressure depression The lowering of the vapor pressure of a solution versus the pure solvent. NaN NaN NaN NaN Viruses An infectious agent that is much smaller and simpler than bacteria. NaN NaN NaN NaN vitamins An organic compound that is essential in very small amounts for the maintenance of normal metabolism. NaN NaN NaN NaN volume The amount of space that a given substance occupies. NaN NaN NaN NaN volume/volume percent A concentration unit that relates the volume of the solute to the volume of the solution. NaN NaN NaN NaN weak base A base that is less than 100% ionized in aqueous solution. NaN NaN NaN NaN zwitterion An electrically neutral compound that contains both negatively and positively charged groups. NaN NaN NaN NaN β-oxidation A sequence of four reactions in which fatty acyl-CoA molecules are oxidized, leading to the removal of acetyl-CoA molecules. NaN NaN NaN NaN