Autotrophs are at the base of food webs. Herbivores, carnivores and decomposers all ultimately get the energy they need from autotrophs. Living organisms use energy to drive chemical reactions. All living organisms use the energy that they obtain to drive all of the chemical reactions necessary for their maintenace, growth and reproduction. These chemical reactions transform matter from the forms in which it is obtained into the compounds that the organism needs.
Enzymes are protein molecules that catalyze specific chemical reactions in organisms.
Enzymes are crucial protein molecules that organisms produce that influence the rates of chemical reactions. Each kind of enzyme has its own particular shape, and consequently catalizes specific chemical reactions. A protein is a chain of amino acids. There are around 20 different kinds of AA's. Each molecule of a given kind of protein has the same sequence of AA's.