Are viruses with bacteria at the left wall of complexity?

Question

I need this info for a paper that is due today. My cat flipped the switch on the power strip and I lost all my work.

If you have a source, please cite it.

Also, what does this mean? "Retroviruses integrate a DNA intermediate of their RNA genome into the host genome, and therefore have a higher chance of correcting any mistakes in their genome thanks to the action of proof-reading DNA polymerases belonging to the host cell."

I think it means that an RNA virus mutates rapidly because it doesn't have DNA proofreading but can still have the advantages because it leeches off its host. Am I right?

Answer 1

If "left wall of complexity" means not complex, then, yes, viruses are the simplesty form of life, if you can even call them alive. Bacteria range greatly in their "complexity" but for the most part are less complex than eukaryotic organisms.

As far as the second part of your question goes, the statement is pretty misleading if not flat out false. Retroviruses such as HIV make most of their mistakes when they copy their RNA to DNA, before the host DNA polymerase does any replication. So it is true that the host DNA polymerase makes less mistakes, but it is faithfully replicating the mutations created by the virus. The DNA polymerase does not in any way make retrovirus replication less error prone.

Answer 2

Kinda sorta, but not really. Viruses are simple in that they consist of an outer shell and an inner genome. They come with very few pre-made proteins. They are incapable of replicating their genomes, so they rely on the host's machinery to replicate.
That's the simple answer. Viruses have a lot of complexities to them. They have specially designed systems to evade the host immune response. Some are retroviruses, meaning they go through an RNA intermediate to insert their genes into the genome. This requires a reverse transcriptase protein. HIV makes its proteins in a unique way- it synthesizes one long protein, then cleaves it to create smaller, functional proteins.
Bacteria really aren't so simple either. Yes, they're unicellular and prokaryotic, but simplicity is in the eye of the beholder. Bacteria are able to stand so many environmental stresses, from insanely high temperatures, to few energy sources, to antibiotics. This is because they replicate so quickly and with just low enough fidelity, they're able to adapt quickly.
So yes, in terms of organisms in general, bacteria and viruses are quite simple. But when you look at these for what they really are, they can become quite complex.