Q3ITD - Campbell Biology

Question

Which bacterium has an rRNA gene that is most similar to that of the wheat mitochondrion? What is the significance of this similarity?

Step-by-Step Solution

Answer

The phylogenetic relationship between species can be identified using the 16s rRNA because of their unique properties. The rRNA sequence similar to that of the wheat mitochondria is the Agrobacterium tumefaciens, an alpha proteobacterium.

 

The similarity between these two species signifies the theory of endosymbiosis; this theory suggests a relation where the eukaryotic cells have arisen from the prokaryotic organisms.

Step 1: Ribosomal RNA (rRNA)

Ribosomal RNA is the subunit of RNA (ribonucleic acid)responsible for synthesizing proteins. The 16s rRNA is easily available, and sequencing is generally not prone to mutation. They help in determining the eukaryotic origin and relation with prokaryotes. 

 

Step 2: Endosymbiotic theory

The theory of endosymbiosis states an evolutionary lead that the eukaryotic cell develops from a prokaryotic organism. It further explains that the organelles such as mitochondria and chloroplast evolved when an aerobic prokaryotic cell ingested an anaerobic bacterium.

Step 3: Bacterium similar to the wheat mitochondrion

The most similar bacterium to the wheat mitochondrion is analyzed by their 16s rRNA, which is highly reliable due to their low mutating property. The similar one is the Agrobacterium tumefaciens that live inside plant tissue and can develop a tumor. 

 

The significance that this similar organism show is that they have an endosymbiotic relationship. This theory provides evolutionary evidence that the prokaryotic organism during division or other environmental factors gave rise to the eukaryotic cells.