Introduction to Viruses: Study Notes

For the complete syllabus, check out our PMDC MDCAT Syllabus 2025 article.

Viruses have characteristics of both living and non-living things. Let's compare these characteristics for better understanding.

Living characteristics of viruses:

- Viruses can reproduce by utilizing the contents of host cells, similar to living organisms.

- They possess genetic material (DNA or RNA), which can mutate over time.

- Viruses interact genetically and physiologically with the organisms they infect.

- As intracellular parasites, viruses can be damaged by ultraviolet rays, much like other living cells.

Non-living characteristics of viruses:​

- Viruses can remain inactive for extended periods without replicating.

- They lack cellular organelles and cannot perform metabolism or generate energy molecules.

- They do not exhibit vital activities such as respiration, excretion, or movement.

- Outside of a host cell, viruses exist as non-living, non-reactive particles.

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