Prokaryotic and Eukaryotic Cells

The earth ecosystems support a diversity of life once organized under five kingdoms. In March 1990, biologists led by Carl Woese, proposed new distribution of life forms under what is now accepted as domains. The three domains, Bacteria, Archaea, and Eucarya, group according to general similarities among members. Each domain contains more specific branches still known as kingdoms. The implementation of domains reorganized the horizontal outlay of biology, catalyzed by the original discovery of archaebacteria now called Archaea.

Prokaryotes Represent Before Nucleus Cells

Prokaryotic organisms are simple life forms usually invisible to the naked eye. Organisms in Domain Bacteria and Domain Archaea contain prokaryotic cells. A prokaryote lacks a nucleus and organelles which function as independent workers in more complex cells. It may be simplicity that perpetuates the survival and massive population of prokaryotic life forms. Serving primarily as decomposers, prokaryotes recycle and add balance to all life on earth. While Bacteria and Archaea are generally grouped together based upon cell composition and history, or cytology, Archaea suggest more complexity on a molecular and evolutionary level.

Eukaryotic Cells Consume and Decompose

The original Plant and Animal classifications that once defined the ecosystem now fall under the broader, more specific title of Eukarya Domain. Most kingdoms defined under domain Eukarya contain more than one cell, with each cell housing a nucleus and organelles. A eukaryote is further coded by its consumption method. Fungi, like most prokaryotes, decompose waste, while animals typically consume, and plants produce through photosynthesis. Given this classification method, it is understandable that protists, mysterious members of domain Eukarya, spark debate among taxonomists.

Protists May Call for More than One Kingdom

Protozoa and algae are familiar members of the Protist kingdom. However, it seems further clarification is necessary if considering modes of nutrition. For example, protozoa consume from the environment and algae contribute to the environment by converting carbon dioxide and water to oxygen through photosynthesis . If domain Eukarya is to remain consistent, the method of classification should remain consistent by ordering based on nutrition. The classification of kingdoms also relies heavily upon cell history and organism evolution. Members of the Protist kingdom display a vast historical discrepancy as indicated by molecular research. A majority of scientists believe the newest information demands reclassification of Protists into more kingdoms because of historical incongruity.

References

Campbell, N.A., Reece, J.B., Taylor, M.R. & Simon, E.J. (2006). Biology: Concepts and Connections. San Francisco, CA: Pearson Education, Inc.

Woese, C.R., Kandler, O., & Wheelis, M.L. (1990, March 26). Towards a natural system of organisms: Proposal for the domains Archaea, Bacteria, and Eucarya. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 87 (12).