Enzymes are absent in viruses. Unlike fungi, slime molds, and bacteria, which are living organisms with cellular structures and metabolic processes that involve enzymes, viruses are much simpler entities. Viruses consist mainly of genetic material (either DNA or RNA) enclosed in a protein coat and lack the cellular machinery necessary for metabolism or enzyme production. Instead, viruses rely on the host cell’s machinery to replicate and produce the proteins they need for their life cycle. This absence of enzymes and cellular metabolism is one of the reasons viruses are considered non-living and exist on the boundary between living and non-living matter.