Glossary

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.

Amylase | An enzyme found in saliva that breaks down starch into simple sugars.

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

Aquaculture | The underwater cultivation of animals and plants for food or for other purposes.

-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.

ATP synthase | An enzyme in mitochondria that produces ATP by adding a phosphate group to the molecule ADP.

Base | A nitrogen-containing building block of DNA; the two types are the purines adenine (A) and guanine (G), and the pyrimidines thymine (T) and cytosine (C).

Bi- | A prefix meaning two.

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

Biochip | An electronic device containing organic materials.

Biopolymer | In a living organism, any large molecule (such as a protein, nucleic acid, lipid, or polysaccharide) made from smaller parts.

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).

Carbohydrate biology | A branch of chemistry dedicated to the study of the many types of carbo-hydrate molecules.

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.

Catalytic antibody | An antibody that speeds up a chemical reaction; also called "abzymes," these antibodies use a molecule called a hapten to mimic the middle, "transition" state of a reaction.

Chaperone | Any of a class of proteins that helps proteins fold or escorts proteins or other molecules throughout the cell.

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 large so-called "libraries" of new synthetic compounds.

Coprophile | A feces-loving organism.

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

Cyanobacteria | A type of bacteria living in damp soil or rocks, or fresh or salt water, that performs photosynthesis, a process in which light, energy, water, and carbon dioxide are converted into oxygen and carbohydrates (sugars).

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.

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.

Endotoxin | Any of a class of lipids found in the outer membranes of gram-negative bacteria; in people, the toxins cause diarrhea and/or septic shock.

Enterocci | Intestinal bacteria that are often resistant to the antibiotic vancomycin.

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.

Glycolipid | A lipid covalently linked to a sugar.

Glycoprotein | A protein covalently linked to a sugar.

Glycosaminoglycan | A large molecule found on the surface of membrane-encased cells that consists of a network of long, branched chains of sugars and smaller, nitrogen-containing molecules.

Hexa- | A prefix meaning six.

Host-guest chemistry | A branch of chemistry in which researchers study the interactions between two molecules (natural or synthetic) with the goal of either mimicking or blocking a biological effect caused by the molecules' interaction.

Hydrocarbon | An organic molecule consisting of hydrogen and carbon atoms only.

-ine | A suffix common to many of the amino acids.

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

Inorganic | Describing a substance 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.

Lipid A | A key component of lipopolysaccharide.

Lipo- | A prefix meaning "lipid," or fat.

Lipopolysaccharide | An integral part of the outer cell membrane of certain types of bacteria (so-called "gram-negative" strains).

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.

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.

Neoglycopolymer | A glycoprotein mimic; a synthetic molecule consisting of polymers with carbohydrates attached.

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.

Olefin metathesis | A chemical reaction in which all of the double bonds in a hydrocarbon molecule are broken and then rearranged.

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.

Organophosphate | A class of toxic organic molecules containing phosphate, and often fluoride, that are used as insecticides and nerve gases (such as sarin); many of these molecules block the action of an enzyme (acetylcholinesterase) that recycles an important brain chemical called acetylcholine.

-ose | A suffix common to many carbohydrates.

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.

Peptidomimetic | A chemical compound that mimics the ability of a peptide to recognize certain physiological molecules, such as proteins and DNA.

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

Phenylketonuria | A genetic disorder in which the body cannot break down the amino acid phenylalanine; abbreviated PKU.

Phosphate group | A chemical unit consisting of an atom of phosphate bound to four oxygen atoms; often attached to other biological molecules, such as proteins, sugars, and lipids.

Phospho- | A prefix meaning phosphate-containing.

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

Phosphotriesterase | A bacterially produced enzyme that breaks down organophosphates like sarin.

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.

Product | A substance formed as the result of a chemical reaction.

Protecting group | A removable chemical unit used by synthetic chemists to purposefully cover up certain regions of a molecule so they do not react with other compounds during a 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.

Protein synthesis | The process in which the genetic code carried by messenger RNA directs cellular organelles called ribosomes to produce proteins from amino acids.

Reaction rate | A measure of how fast a chemical reaction occurs.

Ribonucleotide reductase | The enzyme in all organisms that catalyzes the conversion of nucleosides to deoxynucleosides.

RNA | Ribonucleic acid; a chemical found in cells that serves as an intermediate in the synthesis of proteins; the three major types are called messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA).

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.

Suicide substrate | An enzyme substrate that itself is not toxic but that produces a toxic metabolic product.

Superoxide dismutase | A copper-and zinc-containing enzyme present in all oxygen-using organisms that scavenges free radicals and converts them into hydrogen peroxide and oxygen.

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

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.