No. The presence of DNA is only 1 of 4 conditions for life, as spelled
out in Module 1. Please note that the presence of RNA is NOT a condition
for life, so the viruses that use RNA do not even meet that criterion.
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Remember the other 3 conditions:
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- Ability to sense and respond to the surroundings
- Ability to take in energy from the surroundings and convert it into energy to sustain itself (In other words, life needs food)
- Ability to reproduce
Viruses have #2, but they do not have #3. They do not produce their own
food or eat other food. They also really don’t have #4. The only way
they can reproduce is by invading a living cell and hijacking its
reproductive machinery.
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Thus, since viruses do not have two of the four characteristics of life,
we do not consider them to be living. They are just highly-structured and
complex chemicals. Remember, arsenic can invade and kill a cell, and it
is not alive, either! It is just a chemical. Viruses are just very
complicated chemicals.