Final answer:
A virus structurally consists of an outer capsid made of protein and a core containing genetic material (DNA or RNA). The capsid protects the nucleic acid and aids in the virus's ability to infect host cells.
Step-by-step explanation:
Viruses lack metabolic machinery and are considered noncellular entities, making them different from living organisms that possess a cellular structure. A virus always has an outer capsid composed of protein that provides protection and a core of genetic material, which can be either DNA or RNA but never both. This core contains the essential information for the virus to replicate itself, albeit with the help of a host cell's metabolic machinery. The question can be answered by pointing out that structurally, a virus always has an outer capsid composed of protein and a core of genetic material.