Viruses are considered controversial organisms: some scientists believe they are living because they contain DNA, the genetic code of life, while other scientists believe that they are non-living, because they cannot reproduce without a host organism (living body that a virus infects).
|
Biotic Theory Viruses contain DNA, the fundamental requirement for life. Because they contain DNA, they are able to carryout life processes. Viruses have evolved to exploit the resources of other organisms, therefore requiring only minimal cell function. Although they are incapable of reproducing on their own, viruses have the built-in genetic code to program other cells to reproduce. This suggests that they were once capable of independent replication, and therefore should be classified as living organisms. |
|
Abiotic Theory All living things are able to carry out the basic life functions: metabolism, excretion and reproduction. Viruses are unable to reproduce without infecting a host cell, and therefore do not meet the criteria of “living”. Viruses do contain genetic material, suggesting that they are a primitive precursor to the more complex organisms that evolved to independently reproduce. |