Ribosomes are very old structures,found in all organisms (except viruses),from bacteria to humans.As a result,molecular taxonomists are looking at relationships based upon which rRNA sequence(s)?
A)16S
B)18S
C)30S
D)both choices A and B
E)all of the above

Question

Quizplus · Accepted Answer

Ribosomes are composed of two subunits, the small subunit (30S in bacteria) and the large subunit (50S in bacteria). The 16S rRNA gene is found in the small subunit of the ribosome and is highly conserved among different bacterial species. Likewise, the 18S rRNA gene is found in the small subunit of eukaryotic ribosomes and is highly conserved among different eukaryotic species. Therefore, molecular taxonomists use these rRNA sequences (16S and 18S) to determine the phylogenetic relationships between organisms. As ribosomes are found in all organisms (except viruses), these sequences can be used to analyze relationships across a wide range of taxa. Thus, the best choice is D, both choices A and B.

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