virusëve

Virusët are microscopic infectious agents that can only replicate inside the living cells of other organisms. They are found in nearly all ecosystems of Earth and are the most numerous type of biological entity. The origin of the virus world is still unclear, with some theories suggesting they arose from plasmids or transposons, while others propose they may have existed before or concurrently with cellular life.

Viruses infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. They are obligate intracellular parasites, meaning they lack the metabolic machinery to replicate on their own and must hijack the host cell's machinery to produce more virus particles, known as virions. This process often damages or destroys the host cell, leading to disease in multicellular organisms.

The structure of a virus is generally simpler than that of a cell. A virion consists of genetic material, either DNA or RNA, enclosed within a protective protein coat called a capsid. Some viruses also have an outer lipid envelope derived from the host cell membrane. Viruses are not considered living organisms by many definitions because they lack cellular structure and do not exhibit metabolic processes. Their ability to cause disease, however, makes them significant in medicine and biology. Research into viruses, known as virology, is crucial for understanding infectious diseases, developing vaccines and antiviral therapies, and exploring their role in evolution.