A Detailed Report on the Origins of the Eukaryotic Cell

This report delves into the fascinating topic of eukaryotic cell origins, exploring the evolutionary journey from prokaryotic cells to the complex structures we see today. It discusses the significance of DNA sequencing and the impact of archaea in understanding these origins. The report highlights the endosymbiosis theory as a key explanation, supported by genomic data, which suggests that organelles like mitochondria and chloroplasts were once independent prokaryotic cells. The report references key publications in the field and provides a concise overview of the current understanding of eukaryotic cell development, emphasizing the role of comparative genetics and the ongoing research that continues to shape our understanding of this fundamental biological process.

Running head:BIOLOGY
The Story behind the Eukaryotic Origin
Name of the Student
Name of the University
Author Note

1BIOLOGY
Throughout the ages, there have been many theories behind the origin of the
Eukaryotic cell. Some being simple, some complex and some simply too hard to fathom. The
origin the eukaryotic cell was no doubt a stepping stone for the evolution of species; hence it
is even more important that the evolutionary biologists come up with a logical explanation for
the synthesis of such an outstanding element. The complexity of the eukaryotic cell is
baffling when kept besides its ancestor, aka the prokaryotic cell. Every understanding of
Biology comes down to the level of single cells. As Stephen Jay Gould comments- humans
are living in the 'Age of Bacteria' (Gould, 1996). The transition line from prokaryotic cells to
eukaryotes is considerably fuzzy, and hence the theories have been mere hypothesis as well.
Thankfully, DNA sequencing has come to the rescue, better than before. In most books, the
eukaryotes are divided from the prokaryotes and archaea by a long line that depicts
uncertainty. However, after further phylogenetic study, the two-branched tree has come into
play that depicts that the eukaryotes are formed as a subpart of the archaea and this is
currently the more favoured way. This is because a metagenomic sequencing of a new group
of archaea called Lokiarchaeota show them to be the closest ancestors of the eukaryotes to be
found till date (Embley and Williams, 2015). It has been a long time since the 'On the Origin
of Species' by Darwin was written. While it remains something resembling a bible to the
biologists, many theories have been modernised with the conception of DNA sequencing.
Comparative genetics has allowed the proper analysis of ancestry (Koonin, 2009). Apart from
the complex last ancestor of the eukaryotes, the major hypothesis remains to be of the
endosymbiosis theory. Molecular and genomic data strongly suggest that the complexities of
the eukaryotes came into play almost readymade. The modern endosymbiosis theory suggests
that the organelles of the eukaryotes used to be different prokaryotic cells. The bigger cell
simply just engulfed the smaller cells, which then formed the organelles in the eukaryotic
cells (Keeling, 2014). These prokaryotic cells may have had a symbiotic relationship with

2BIOLOGY
each other, primarily. The major evidence that suggests this is that chloroplasts and
mitochondria have their own DNA. While this seems too simple to be a logical theory, the
genomic data has shown promising evidence as well, deeming this hypothesis to be the most
plausible of all.

3BIOLOGY
Reference
Embley, T.M. and Williams, T.A., 2015. Steps on the road to eukaryotes. Nature, 521(7551),
pp.169-170.
Keeling, P.J., 2014. The impact of history on our perception of evolutionary events:
endosymbiosis and the origin of eukaryotic complexity. Cold Spring Harbor perspectives in
biology, 6(2), p.a016196.
Koonin, E.V., 2009. Towards a postmodern synthesis of evolutionary biology.
Stephen Jay Gould, "Planet of the Bacteria," Washington Post Horizon, 1996, 119 (344): H1;
Reprinted here with permission; This essay was adapted from Full House, New York:
Harmony Books, 1996, pp. 175-192.