Ch 3 Glossary

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Chapter 3

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BIOLOGY

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alcohol

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Organic compound that includes one or more hydroxyl groups (-OH); it dissolves readily in water. Sugars are examples.

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amino acid

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Organic compound with an H atom, amino group, acid group, and R group, all covalently bonded to a carbon atom. Subunit of polypeptide chains.

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ATP

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Adenosine triphosphate (ah-den-uh-seen try-foss-fate). Nucleotide with adenine, ribose, and three phosphate groups that drives most energy-requiring metabolic reactions.

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carbohydrate

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Molecule of carbon, hydrogen, and oxygen mostly in a 1:2:1 ratio. Main kinds are monosaccharides, oligosaccharides, and polysaccharides. They are structural materials, energy stores, and transportable energy forms.

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coenzyme

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Nucleotide that accepts electrons, H atoms that enzymes strip from substrates and transfers them to a different reaction site.

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condensation reaction

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Covalent bonding of two molecules into a larger one; water often forms as a by-product.

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denaturation

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Loss of a molecule's three-dimensional shape as weak bonds (e.g., hydrogen bonds) are disrupted.

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disaccharide

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[Gk. di, two, + sakcharon, sugar] A common oligosaccharide; two covalently bonded sugar monomers.

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DNA

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Deoxyribonucleic acid. Of cells and many viruses, the molecule of inheritance. H bonds join its two helically twisted nucleotide strands, one of which has instructions (in its base sequence) for synthesizing all of the enzymes and other proteins required to build and maintain cells.

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enzyme

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A type of protein or one of the few RNAs that catalyze reactions between substances, most often at functional groups.

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fat

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Lipid with a glycerol head and one, two, or three fatty acid tails. Unsaturated tails have single covalent bonds in the carbon backbone; saturated tails have one or more double bonds.

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fatty acid

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Molecule with a backbone of up to 36 carbon atoms, a carboxyl group (-COO- or -COOH) at one end, and hydrogen atoms at most or all of the other bonding sites.

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functional group

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An atom or group of atoms that is covalently bonded to the carbon backbone of an organic compound and that influences its chemical behavior.

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functional-group transfer

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Enzyme-mediated event in which a molecule donates one or more functional groups to another molecule.

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glyceride

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Molecule having one, two, or three fatty acid tails attached to a glycerol backbone; one of the fats or oils.

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glycogen

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A highly branched polysaccharide consisting of glucose monomers; the main storage carbohydrate in animals.

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glycoprotein

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Protein with linear or branched oligosaccharides covalently bonded to it; most surface proteins of animal cells and many proteins circulating in blood are glycoproteins.

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hemoglobin

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[Gk. haima, blood, + L. globus, ball] An iron-containing respiratory protein of red blood cells.

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hydrocarbon

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Organic compound that has only hydrogen atoms attached to the carbon backbone.

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hydrolysis

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[L. hydro, water, + Gk. lysis, loosening] Cleavage reaction that breaks covalent bonds and splits a molecule into two or more parts. H+ and OH- (from a water molecule) are often attached to the newly exposed bonding sites.

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lipid

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A mostly greasy or oily hydrocarbon; strongly resists dissolving in water but readily dissolves in nonpolar substances. All cells use lipids as storage forms of energy, structural materials as in membranes, and cell products.

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monomer

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Small molecule used as a subunit of polymers, such as sugar monomers of starch.

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monosaccharide

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[Gk. monos, alone, single, + sakcharon, sugar] One of the simple carbohydrates (e.g., glucose).

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nucleic acid

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Single- or double-stranded chain of four kinds of nucleotides joined at their phosphate groups. Nucleic acids (e.g., DNA, RNA ) differ in base sequences.

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nucleotide

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Small organic compound with deoxyribose (a five-carbon sugar), a nitrogenous base, and a phosphate group. Monomer for adenosine phosphates, nucleotide coenzymes, and nucleic acids.

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oligosaccharide

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Short-chain carbohydrate of two or more covalently bonded sugar monomers (e.g., disaccharides).

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organic compound

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Molecule of one or more elements covalently bonded to some number of carbon atoms.

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phospholipid

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Organic compound that has a glycerol backbone, two fatty acid tails, and a hydrophilic head of two polar groups (one being phosphate). Phospholipids are the main structural component of cell membranes.

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polymer

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[Gk. polus, many, + meris, part] Large molecule of three to millions of monomers of the same or different kinds.

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polypeptide chain

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An organic compound of three or more amino acids joined by peptide bonds; atoms of its backbone have this pattern: -N-C-C-N-C-C- . All proteins are composed of one or more polypeptide chains.

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polysaccharide

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[Gk. polus, many, + sakcharon, sugar] Straight or branched chain of many covalently linked sugar units of the same or different kinds. In nature, the most common types are cellulose, starch, and glycogen.

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protein

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Organic compound composed of one or more polypeptide chains.

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rearrangement, molecular

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Conversion of one organic compound to another through changes in its internal bonds.

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RNA

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Ribonucleic acid. Any of a class of single-stranded nucleic acids that function in transcribing and translating the genetic instructions encoded in DNA into proteins.

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sterol

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Lipid with a rigid backbone of four fused carbon rings (e.g., cholesterol). Sterols differ in the number, position, and type of their functional groups.

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toxin

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Normal metabolic product of a species that can hurt or kill a different species.

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triglyceride

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(neutral fat) A type of lipid that has three fatty acid tails attached to a glycerol backbone. Triglycerides are the body's most abundant lipids and its richest energy source.

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COVALENT BONDING

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THE CHEMICAL BOND BETWEEN 2 ATOMS MADE BY THE SHARING OF 2 ELECTRONS