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Vocab Words

a molecule composed of the sugar ribose, the base adenine, and three phosphate groups; the major energy carrier in cells. The last two phosphate groups are attached by "high-energy" bonds.

adenosine triphosphate

the individual subunit of which proteins are made, composed of a central carbon atom bonded to an amino group a carboxyl group a hydrogen atom, and a variable group of atoms denoted by the letter R.

amino acid

one of the nitrogen-containing, single- or double-ringed structures that distinguishes one nucleotide from another. In DNA, the bases are adenine, guanine, cytosine, and thymine.

base

a compound composed of carbon, hydrogen, and oxygen, with the approximate chemical formula includes sugars, starches, and cellulose.

carbohydrate

an insoluble carbohydrate composed of glucose subunits; forms the cell wall of plants.

cellulose

a compound found in the cell walls of fungi and the exoskeletons of insects and some other arthropods; composed of chains of nitrogen-containing, modified glucose molecules.

chitin

a chemical reaction in which two molecules are joined by a covalent bond with the simultaneous removal of a hydrogen from one molecule and a hydroxyl group from the other, forming water; the reverse of hydrolysis.

dehydration synthesis

having the secondary and/or tertiary structure of a protein disrupted, while leaving the amino acid sequence unchanged. Denatured proteins can no longer perform their biological functions.

denatured

a molecule composed of deoxyribose nucleotides; contains the genetic information of all living cells.

deoxyribonucleic acid

a carbohydrate formed by the covalent bonding of two monosaccharides.

disaccharide

the covalent bond formed between the sulfur atoms of two cysteines in a protein; typically causes the protein to fold by bringing otherwise distant parts of the protein close together.

disulfide bond

a protein catalyst that speeds up the rate of specific biological reactions.

enzyme

a lipid composed of three saturated fatty acids covalently bonded to glycerol; fats are solid at room temperature.

fat (molecular)

an organic molecule composed of a long chain of carbon atoms, with a carboxylic acid (COOH) group at one end; may be saturated (all single bonds between the carbon atoms) or unsaturated (one or more double bonds between the carbon atoms).

fatty acid

one of several groups of atoms commonly found in an organic molecule, including hydrogen, hydroxyl, amino, carboxyl, and phosphate groups, that determine the characteristics and chemical reactivity of the molecule.

functional group

the most common monosaccharide, with the molecular formula most polysaccharides, including cellulose, starch, and glycogen, are made of glucose subunits covalently bonded together.

glucose

a three-carbon alcohol to which fatty acids are covalently bonded to make fats and oils.

glycerol

a coiled, springlike secondary structure of a protein.

helix

the chemical reaction that breaks a covalent bond by means of the addition of hydrogen to the atom on one side of the original bond and a hydroxyl group to the atom on the other side; the reverse of dehydration synthesis.

hydrolysis

describing any molecule that does not contain both carbon and hydrogen.

inorganic

a disaccharide composed of glucose and galactose; found in mammalian milk.

lactose

one of a number of organic molecules containing large nonpolar regions composed solely of carbon and hydrogen, which make lipids hydrophobic and insoluble in water; includes oils, fats, waxes, phospholipids, and steroids.

lipid

a disaccharide composed of two glucose molecules.

maltose

a small organic molecule, several of which may be bonded together to form a chain called a polymer.

monomer

the basic molecular unit of all carbohydrates, normally composed of a chain of carbon atoms bonded to hydrogen and hydroxyl groups.

monosaccharide

an organic molecule composed of nucleotide subunits; the two common types of nucleic acids are ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

nucleic acid

a subunit of which nucleic acids are composed; a phosphate group bonded to a sugar (deoxyribose in DNA), which is in turn bonded to a nitrogen-containing base (adenine, guanine, cytosine, or thymine in DNA).

nucleotide

a lipid composed of three fatty acids, some of which are unsaturated, covalently bonded to a molecule of glycerol; oils are liquid at room temperature.

oil

describing a molecule that contains both carbon and hydrogen.

organic

a chain composed of two or more amino acids linked together by peptide bonds.

peptide

the covalent bond between the nitrogen of the amino group of one amino acid and the carbon of the carboxyl group of a second amino acid, joining the two amino acids together in a peptide or protein.

peptide bond

a lipid consisting of glycerol bonded to two fatty acids and one phosphate group, which bears another group of atoms, typically charged and containing nitrogen. A double layer of phospholipids is a component of all cellular membranes.

phospholipid

a form of secondary structure exhibited by certain proteins, such as silk, in which many protein chains lie side by side, with hydrogen bonds holding adjacent chains together.

pleated sheet

a molecule composed of three or more (perhaps thousands) smaller subunits called monomers, which may be identical (for example, the glucose monomers of starch) or different (for example, the amino acids of a protein).

polymer

a large carbohydrate molecule composed of branched or unbranched chains of repeating monosaccharide subunits, normally glucose or modified glucose molecules; includes starches, cellulose, and glycogen.

polysaccaride

the amino acid sequence of a protein.

primary structure

a polymer composed of amino acids joined by peptide bonds.

protein

the complex three-dimensional structure of a protein consisting of more than one peptide chain.

quaternary

a molecule composed of ribose nucleotides, each of which consists of a phosphate group, the sugar ribose, and one of the bases adenine, cytosine, guanine, or uracil; involved in converting the information in DNA into protein; also the genetic material of some viruses.

ribonucleic acid

referring to a fatty acid with as many hydrogen atoms as possible bonded to the carbon backbone (therefore, a saturated fatty acid has no double bonds in its carbon backbone).

saturated

a repeated, regular structure assumed by a protein chain, held together by hydrogen bonds; for example, a helix.

secondary structure

a polysaccharide that is composed of branched or unbranched chains of glucose molecules; used by plants as a carbohydrate-storage molecule.

starch

a lipid consisting of four fused carbon rings, with various functional groups attached.

steroid

a disaccharide composed of glucose and fructose.

sucrose

a simple carbohydrate molecule, either a monosaccharide or a disaccharide.

sugar

the complex three-dimensional structure of a single peptide chain; held in place by disulfide bonds between cysteines.

tertiary structure

a type of fat produced during the process of hydrogenating oils that may increase the risk of heart disease. The fatty acids of trans fats include an unusual configuration of double bonds that is not normally found in fats of biological origin.

trans fat

a lipid composed of three fatty-acid molecules bonded to a single glycerol molecule.

triglyceride

referring to a fatty acid with fewer than the maximum number of hydrogen atoms bonded to its carbon backbone (therefore, an unsaturated fatty acid has one or more double bonds in its carbon backbone).

unsaturated

a lipid composed of fatty acids covalently bonded to long-chain alcohols.

wax

a highly branched polymer of glucose that is stored by animals in the muscles and liver and metabolized as a source of energy.

glycogen

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