Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

I find it interesting that all life on earth use DNA. I've seen video on how helicase and ribosomes work together to copy DNA sequences (to RNA) with helicase then recreate them using ribosomes. Does this process work the same way in the simplest life forms? Bacteria and other unicellular life that reproduce through mitosis, for example?

share|improve this question
1  
Although the definition of life is complicated, there’s general agreement that viruses aren’t alive. Furthermore, there seems to be a misconception about the mechanism of DNA replication: no intermediate step via RNA is involved. Maybe you could clarify what you mean here? Still, I think this is a good question. –  Konrad Rudolph Jul 20 '12 at 12:50
    
You seem to have got confused between translation (making proteins from RNA templates using ribosomes) and DNA replication (direct DNA-DNA copying) –  Richard Smith-Unna Jul 20 '12 at 15:35

2 Answers 2

First, mitosis is a eukaryotic process where not only genome replication and cell division is involved but quite a few more processes, not the least because there is a nucleus in eukaryotes. Bacteria simply divide after replication. And yes, even the simplest bacteria (and even some symbionts) use ribosomes for protein production. Example:

The smallest bacteria are from species Mycoplasma. The Mycoplasma species with the smallest annotated proteome on UniProt is Mycoplasma genitalium (strain ATCC 33530 / G-37 / NCTC 10195, with 484 genes. I have attached links to the set, as well as to its helicase. (For the 16S gene you would look that up in a gene not protein database)

http://www.uniprot.org/uniprot/?query=taxonomy:243273

http://www.uniprot.org/uniprot/P47340

share|improve this answer

I've had a direct look at Carsonella rudii, which is I believe is the bacterial genome with the smallest number of genes so far - 184 as well as being only 160 kb in length. It has a putative DNA helicase encoded in it. 37 of those genes encode for ribosomal components as well.

If there was ever a bacterium or any living cell (non virus that is) discovered without a ribosome, you would have heard about it. nobel prizes all around.

So I would say that your answer is yes.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.