How is a virus different from living organisms?

Viruses differ from living organisms primarily in that they lack cellular structure and metabolism. Living organisms are composed of cells, which are the basic units of life. These cells carry out metabolic processes necessary for growth, reproduction, and survival. In contrast, viruses are acellular entities, meaning they do not have a cellular structure; they consist of genetic material (either DNA or RNA) surrounded by a protein coat, but they do not possess any cellular machinery to conduct metabolic processes.

Additionally, viruses are obligate intracellular parasites. They cannot reproduce independently and must invade a host cell to replicate. This reliance on host cellular machinery further emphasizes their distinction from living organisms. Unlike living entities that exhibit the characteristics of life, such as metabolism and growth, viruses do not carry out any of these processes on their own. This fundamental difference is what classifies viruses as unique biological entities, separate from living organisms.