The Three Domains of Life - Article Analysis Essay

Introduction

The question of the origin of the three domains of life is a difficult one for many. The important aspect is to separate the three domains. Nonetheless, a number of recent species of bacteria have led to an inference that the three domains have some form of continuity between them. The article "Domain Cell Theory supports the independent evolution of the Eukarya, Bacteria, and archaea and the Nuclear Compartment Commonality hypothesis" by Janes Staley shows the origins and the evolution of the three domains. Charles Darwin failed to address these divisions-Bacteria, archaea, and eukaryotes-and instead focused on the kingdoms Animalia and Plantae. Scientific studies by people such as Carl Woese have revealed evidence of these divisions that form the tree of life.

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The article explains that the three domains have insertion systems for the membrane protein membrane, ribosomes, RNA polymerase, and similar genetic code. The three domains trace their common origin as the Last Universal Common Ancestor (LUCA). Each of the domains diverges from the common ancestor to develop its distinct characteristics (Staley 17). Additionally, bacteria and archaea have a set of common characteristics including a circular chromosome that has genes in operon arrangement. There is an evolutionary link between eukaryotes and archaea which is shown in the expression of their gene machinery as well as an increase in the belief that archaea and eukaryotes have a common ancestor that they share excluding the bacteria, that is, the Last Archaeal and Eukaryotic Common Ancestor (LAECA). In spite of that, it is clear that a larger portion of the genes of Eukaryotes is linked to bacteria than to Archaea.

The article proves a difficult task in the evaluation of the relationship between the evolutions of bacterial features such complex cell plans and membrane coats. This is due to the lack of a common sequence between Planctomycetes, Verrucomicrobiae, and Chlamydiae (PVC) proteins and their counterparts that do not have a bacterial origin (Staley 21). The lack of pattern raises concerns that there may be a misinterpretation of the common features observed or at best it could only be a convergence. There is also a proposition that the archaeal and eukaryotic characteristics in bacteria are a demonstration that intermediate forms existed before the three domains came to be known. Therefore, I agree with this inference of the article due to its rejection of earlier assertions that there was no evolution of eukaryotic characteristics. Since there are both archaeal and eukaryotic features in bacteria, there is no need for fusion in the explanation of eukaryogenesis.

There has already been an evaluation and rejection of a scenario of fusion between members of PVC due to its requirement for unnecessary assumptions as well as failure to give a convincing explanation to the origin of some traits (Staley 34). The article stresses that the availability of archaeal and eukaryotic traits in the bacterial superphylum is in tandem with complex LUCA that was suggested in the past. This LUCA may have shown traits like endocytosis and sterol production, among others. Nonetheless, the evolution of a complex LUCA necessitates a significant amount of loss in the each of the domains.

We can consider another hypothesis with a bacterial ancestry of the tree of life in which the LPCA was an entity that was linked to LAECA. In this instance, the root would have been the 'cauldron' for archaea's and eukaryotes' evolution (Staley 38). Just like the platypus has a common trait with mammals, reptiles, and birds, the eukaryotic and archaeal characteristics present in members of PVC is indicative of a shared root between the LAECA and bacteria (Card 72). The traits present in LPCA are rooted to the archaeal and eukaryotic ones, as well as the present PVC ones. The traits present in existing PVC members consequently have their origin in LPCA members and do not have a shared origin with the archaeal and eukaryotic characteristics. Therefore, PVC genes and proteins do not signal a common ancestry with eukaryotes and archaea.

The sisterhood between the LAECA and LPCA also presents a probable point of continuity for the occurrence of the membrane of archaea in anammox (Staley 41). Anammox is the only prokaryote that has been established to possess both ether and ester-linked lipids. There is a probability that the LAECA possessed both of these lipids, and they remained in the eukaryotes as the ester part became was retained in archaea. Some scientists may raise the question that the comparison of the genes does not provide an adequate revelation of the bond between planctomycetes (Oliver 16). The main argument against this would be that this is only an illustration of the confines of methods focused on sequence only.

Conclusion

Overall, it is likely that the members of PVC exhibit traits that were also available in LUCA and are normally linked with archaea, eukaryotes, or their combination. Those traits show that there were transitional forms between the three domains, hence eliminating fusion as a requirement for eukaryogenesis and suggesting the complexity of the LUCA. I prefer an instance where the traits present in members of PVC share a bacterial ancestry with LPCA, which is linked to LAECA. Even though the three domains are still the norm in the tree of life, the distinction between them is distorted by the PVC superphylum leading to the suggestion of a connection between these three domains.

Works Cited

Card, Stuart K. The psychology of human-computer interaction. CRC Press, 2017.

Oliver, Richard L. Satisfaction: A behavioral perspective on the consumer. Routledge, 2014.

Staley, James T. "Domain Cell Theory supports the independent evolution of the Eukarya, Bacteria and Archaea and the Nuclear Compartment Commonality hypothesis." Open biology 7.6 (2017): 17-41.