anchedprotein a biological macromolecule composed of one or more chains of amino acidsproton a positively charged particle that resides in the nucleus of an atom; has a mass of 1 and a charge of +1radioactive isotope an isotope that spontaneously emits particles or energy to form a more stable elementribonucleic acid (RNA) a single-stranded polymer of nucleotides that is involved in protein synthesissaturated fatty acid a long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximizedsolvent a substance capable of dissolving another substancestarch a storage carbohydrate in plantssteroid a type of lipid composed of four fused hydrocarbon ringssurface tension the cohesive force at the surface of a body of liquid that prevents the molecules from separatingtemperature a measure of molecular motiontrans-fat a form of unsaturated fat with the hydrogen atoms neighboring the double bond across from each other rather than on the same side of the double bondtriglyceride a fat molecule; consists of three fatty acids linked to a glycerol moleculeunsaturated fatty acid a long-chain hydrocarbon that has one or more than one double bonds in the hydrocarbon chainvan der Waals interaction a weak attraction or interaction between molecules caused by slightly positively charged or slightly negatively charged atomsChapter SummaryThe Building Blocks of MoleculesMatter is anything that occupies space and has mass. It is made up of atoms of different elements. All the 92 elements that occur naturally have unique qualities that allow them to combine in various ways to create compounds or molecules. Atoms