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Chemistry A-Z


Air pollutants Substances directly produced by a process, such as ash from a volcanic eruption or carbon monoxide gas from motor vehicle exhaust

Alkaloids A class of over 3,000 nitrogen-containing chemicals (such as caffeine and cocaine) that are produced by plants but have effects in humans and animals

Amino acids A class of 20 chemical units that are the building blocks of peptides and proteins

Anabolic A type of reaction or series of reactions in which complex molecules are synthesized from simpler ones; the opposite of catabolic

Antibiotic resistance The ability of a microorganism to withstand the effects of antibiotic medicines

-ase A suffix common to many, but not all, enzymes

Atom The smallest particle of matter that maintains the property of an element in the periodic table; atoms are composed of subatomic particles called electrons, neutrons, and protons, which themselves are composed of even tinier subatomic particles such as quarks

ATP Adenosine triphosphate The energy currency of metabolism in all organisms

Bi A prefix meaning two

Biochemistry The scientific study of the chemistry of living cells, tissues, organs, and organisms

Biodegradable Capable of being broken down by the action of living things, such as microorganisms

Biomaterial Any material, natural or synthetic, used and adapted for a medical application

Biosensor A system or device that detects a chemical or chemicals in a biological material

Biotechnology The industrial use of living organisms or biological methods derived through basic research; examples range from genetic engineering to making cheese or bread

Bond Physical forces holding together two atoms in a molecule

Carbohydrate A chemical compound made up of a chain or ring of carbon atoms to which hydrogen and oxygen atoms are attached in a defined ratio (2:1); includes simple sugars like glucose and complex sugars like chitin (the exoskeleton of crabs)

Carbon dioxide A heat-trapping gas (CO2) that plays a role in global warming.

Carbon monoxide A poisonous, local air pollutant (CO) produced when fuel such as petroleum does not burn completely

Carcinogen A substance that has been proven by medical research showing direct correlation to cause cancer in humans

Catabolic A type of reaction or series of reactions in which complex molecules are broken down into simpler ones; the opposite of anabolic

Catalyst A substance that speeds up a chemical or biochemical reaction that would have occurred anyway (without help), but at a much slower rate; enzymes are biological catalysts

Chemical biology A field of study that blends chemistry and biology and involves the application of chemical techniques and tools, often compounds produced through synthetic chemistry, to the study and manipulation of biological systems

Chemical genomics The study of gene responses to chemical compounds. The main goal is to rapidly identify new drugs and drug targets

Chemical library A collection of chemicals that are stored along with related information such as the chemical structure, purity, quantity, and other characteristics of the substance

Cheminformatics The use of computer and information technologies to study problems in chemistry

Chirality The ability of a chemical substance to exist in two mirror-image forms, each of which rotates polarized light in opposite directions

Cholesterol A lipid unique to animal cells that is used in the construction of cell membranes and as a building block for some hormones

Clinical trial A scientific study in which physician-researchers study the effects of potential medicines on people; usually conducted in three phases (I, II, and III) that determine safety, whether the treatment works, and if it's better than current therapies, respectively

Cofactor A helper molecule (either inorganic, such as a metal ion, or organic, such as a vitamin) required by an enzyme

Combinatorial chemistry The random assembly of various chemical units into chemical libraries of new synthetic compounds

Covalent bond A force that holds together two or more atoms, formed when electrons travel between the atoms' nuclei (and are thus "shared")

Di- A prefix meaning two

DNA (deoxyribonucleic acid) A double-stranded molecule that encodes genetic information; composed of four nucleotides containing the bases adenine (A), cytosine (C), guanine (G), and thymine (T)

DNA polymerase An enzyme that copies, and sometimes repairs, DNA

Double bond A type of covalent bond in which a pair of atoms shares two pairs of electrons

Drug delivery Giving a medicine to achieve a therapeutic effect in humans or animals. The most common methods include: oral (through the mouth), topical (skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and rectal) and inhalation (through the lungs)

Electrolyte A charged molecule (such as a sodium or potassium ion) that is present in body fluids

Element A component of the periodic table; a pure substance that cannot be separated into simpler substances by chemical means

Enantiomer One of two "mirror images" of a chiral molecule

Endocrine disruptor A synthetic chemical that blocks, mimics, or otherwise interferes with naturally produced hormones

Enzyme A molecule that acts as a catalyst, speeding up biochemical reactions

Fluorescence The property of giving off light at a particular wavelength (emission wavelength) when illuminated by light of a different wavelength (excitation wavelength)

Forensic science The application of scientific knowledge to questions of civil and criminal law

Genetic engineering The manipulation of an organism's genes-introducing, eliminating, or changing them-using modern molecular biology techniques

Glycan A polysaccharide; a polymer of sugars; see oligosaccharide

Glycolipid A lipid covalently linked to a sugar

Glycoprotein A protein covalently linked to a sugar

Glycoscience A branch of chemistry dedicated to the study of the many types of carbohydrate molecules

Green chemistry A chemical philosophy, also called sustainable chemistry, that encourages the design of products and processes that reduce or eliminate the use and generation of hazardous substances

Greenhouse gas A gas that raises the temperature of the earth's atmosphere by absorbing part of the long-wave radiation reflected back from the earth's surface. Carbon dioxide is an example

Hexa- A prefix meaning six

Hydrocarbon An organic molecule consisting of hydrogen and carbon atoms only. An example is petroleum, which contributes to air pollution when released into the atmosphere

Inflammation The body's reaction to noxious stimuli or foreign particles, resulting in swelling, redness, and pain

Inorganic chemistry The branch of chemistry that studies substances not derived from a living organism and/or not composed of carbon and hydrogen (a hydrocarbon)

In silico Literally "within silicon" refers to modeling research conducted with computers only

Ion An electrically charged atom

Ionic bond A force that holds together two electrically charged atoms (called ions)

Lipid A fatty, waxy, or oily compound that will not dissolve in water; it contains hydrogen, carbon, and oxygen, but proportionally far less oxygen than carbohydrates

Lipo- A prefix meaning "lipid," or fat

Mass spectrometry A technique used to determine the composition and abundance of the atoms in a molecular substance, starting with a very small amount of sample

Medicinal chemistry An area of study involved with designing, making and developing medicines for use in humans and animals

Metabolic engineering The targeted and purposeful alteration (using genetic engineering techniques) of an organism's metabolic pathways in order to better understand how the pathways work or to redesign them to produce a different set of products

Metabolism A set of enzyme-catalyzed reactions in a living organism that builds and breaks down organic molecules, producing or consuming energy in the process

Metabolite A chemical intermediate in metabolic reactions

Model organism A bacterium, animal, or plant used by scientists to study basic research questions; common model organisms include yeast, flies, worms, frogs, and fish

Nano- A prefix meaning one-billionth

Nanotechnology A branch of science and engineering devoted to the design and production of extremely small electronic devices and circuits built from individual atoms and molecules

Natural product A molecule produced by a living organism--a plant, marine organism or microorganism--that often has a medicinal use

Nuclear magnetic resonance spectroscopy A technique used to study the physical, chemical, and biological properties of matter; in this method, scientists subject a molecule to a strong magnet and watch what happens to the atoms that make up the molecule, which provides information about the molecule's compositioN

Nucleic acid A large molecule composed of units of nucleotides; includes both RNA and DNA

Nucleotide A subunit of RNA or DNA containing a base, a phosphate, and a sugar; thousands of nucleotides link up to form a molecule of DNA or RNA

Oligosaccharide A molecule made up of several simple sugars linked together

Organic Carbon-containing

Organic chemistry A branch of chemistry dedicated to the study of the structures, synthesis, and reactions of carbon-containing compounds

Oxo-or oxy- Prefixes meaning oxygen-containing

Peptide A molecule consisting of a chain of amino acids; a small protein fragment

Peptide bond The chemical link joining amino acids in peptides and proteins

Pharmacogenetics The study of how people's genetic make-up affects their response to medicines

Pharmacology The study of drugs, of the body's reaction to drugs, and of the sources of drugs

Phospholipid A lipid made up of glycerol and fatty acids, with a phosphate group attached

Physiology The study of how living organisms function

Plasma membrane The membrane that separates the contents of a cell from its outside environment; it consists of a double layer of phospholipids with embedded proteins

Polymer A large molecule formed by combining many similar, smaller molecules

Polysaccharide Any of a class of carbohydrates consisting of chains of simple sugars; see oligosaccharide, glycan

Product A substance formed as the result of a chemical reaction

Protein A large molecule composed of one or more chains of amino acids in a specific order and folded shape determined by the sequence of nucleotides in the gene encoding the protein


Reaction rate A measure of how fast a chemical reaction occurs

RNA (ribonucleic acid) A chemical found in cells that serves as an intermediate in the synthesis of proteins

Structural biology A branch of biology dedicated to the study of the three-dimensional structures of proteins and other molecules to help understand the function of these molecules in the cell

Substrate A molecule acted upon by an enzyme

Synthetic chemistry A branch of chemistry in which chemists devise ways to make specific molecules of interest and/or develop new chemical reactions for this purpose

Tissue engineering A field of study that combines cells, engineering and materials methods, with the goal of improving or replacing biological functions

Toxicology The study of the harmful effects of chemicals on living organisms

Toxin A poisonous substance

Transition state The activated form of a molecule that has partly undergone a chemical reaction

Tri- A prefix meaning three

van der Waals force A weak physical force that holds together two molecules or two different parts of the same molecule


This page last reviewed on April 22, 2011