Viruses

Viruses are tiny infectious agents that can only replicate inside the living cells of a host. Unlike bacteria, they are not considered living organisms because they lack cellular structure and metabolism. A virus consists of genetic material (either DNA or RNA) surrounded by a protein coat. When a virus infects a host, it hijacks the host's cellular machinery to produce more virus particles. Viruses can cause a range of diseases, from mild colds to serious illnesses like influenza or COVID-19, and they are spread through various means, including respiratory droplets, direct contact, and contaminated surfaces.