Eukaryotic Theory

Eukaryotes are more closely related to Archaea. They both share certain structural similarites that are not seen in bacteria. These similarites include introns, histones, several types of RNA polymerase, and methionine as the first amino acid in protein synthesis. Also, the comparison of nucliec acid sequences shows greater similarity between archaea and eukaryotes. Other evidence shows that the enzymes involved in processes such as transcription and translation are more closely related to in Eukaryotes and Archaea compared to bacteria. In both archaea and eukayotes replication takes place in multiples origin of replication sites compared to that of bacteria which replication only takes place in one origin of replication site. All of this evidence

There are two main types of cells in the world. The simplest cells such as bacteria are known as Prokaryotic cells, and human cells are known as Eukaryotic cells. The main difference between each of these cells is that a eukaryotic cell has a nucleus and a membrane bound section in which the cell holds the main DNA which are building blocks of life.

Prior to the development of DNA technology and the sequencing of organismal genomes, Charles Darwin suggested that the “tree” of life can be traced back to a single root (Koonin and Wolf, 2012). While Darwin’s theory was primitive, it laid the groundwork for the phylogenetic trees that are currently studied in science classrooms around the world. The three-domain tree, containing Eukarya, Archea, and Bacteria, soon became too simplistic due to the realization that some bacteria possessed the ability to exchange genetic information by horizontal gene transfer (Koonin and Wolf, 2012).

Archaea and the origin of life. The word Archaea originated from the Greeks, meaning beginning. Throughout this essay we will go through discovers of Archaea and why they are classified as Prokaryotes and what the actual evolutionary relationship of Archaea to Eukaryotes and bacteria. We will look at the differing views throughout the scientific community in regards to the number of domains. Over whether three domains of life or two domains of life fit in the Tree of life. We will look at some research that has supportive evidence of the same. This essay will then look at the Habitat of Archaea – why many Archaea are classified as extremophiles and how these are not just bacteria’s and that extremophiles are a diverse group

While there are many different hypotheses to the evolution of eukaryotic organisms, two in particular have very plausible yet different approaches to this complex question. The Margulis hypothesis of the evolution of eukaryotic organisms focuses on the idea of endosymbiosis, which is the close interaction or association between different species with one of those species being inhabited within the other. Margulis hypothesized that free-living bacteria that were capable of energy production and photosynthesis where engulfed by a free-living cell. The cell and the bacteria now inside of it formed a mutualistic and symbiotic relationship with the bacteria providing the cell with the energy and food it needs while remaining protected inside the cell. Through evolutionary time this symbiotic relationship would grow so strong that the two individuals would not be able to function alone and thus the eukaryote would arise. The idea was supported by the fact that mitochondria and chloroplasts both have unique genomes that resemble the single circular chromosomes found within bacteria.

The symbiotic union intersects prokaryotic cells with their decedents, the eukaryotic cells. It seems that life surfaced approximately 3.8 billion years ago (Marshall, 2007), with the first cell presumed to have ascended from enclosure of self-replicating RNA (Torres, 2012) in a constituted phospholipid membrane .

Kemaladewi D, Maino E, Hyatt E, Hou H, Ding M, Place K, Zhu X, Baghestani Z, Deshwar A, Merico D, Xiong H, Frey B, Wilson M, Ivakine E, Cohn R (2017) Correction of a splicing defect in a

Prokaryotic cells evolved earlier than Eukaryotic cells this is shown by the fact that Prokaryotic means ‘before nucleus’, this earlier evolution resulted in many differences seen between these cell types (Cain et al, 2014, p172), such as different organisation within the cell. However because all cells are thought to have evolved from a Last Universal Common Ancestor (LUCA) (Heaphy, S, 2015) similarities between these cells are also seen such as ribosomes, however further difference can be found within these similarities. Some of these key differences can be seen in the figures below.

In the replication process of DNA, there are similarities between the process of replication of a Eukaryote cell and Prokaryote cell. There are also differences in both processes. The most notable difference would have to start with the cell themselves, which may add to additional differences in the processes. A prokaryote is a more simplistic cell with less DNA and a Eukaryote cell is much more complex with vast amounts of DNA.

Symbioses have played an important role in the origins and evolution of cells and organisms with novel properties. One of the most significant outcomes of symbiosis, is the formation of eukaryotes through either primary or secondary endosymbiosis which allowed for the development of many unique organelles present today in eukaryotes, notably chloroplasts and mitochondria. Primary endosymbiosis is the engulfment of a prokaryote by a eukaryote forming a plastid, compared to secondary endosymbiosis: a eukaryote engulfs another eukaryote to form a plastid (Archibald et al, 2002). Through endosymbiosis, the endosymbionts are able to bring in unique metabolic and signalling capabilities beneficial to the host (Lake, 2009). However, mutually dependent

It is a fact that 80 % of the earth’s history is solely a microbial life and continues to be a dominant life form. Living organisms can be grouped into three different domains: Archaea, Bacteria, and Eukarya. The differences between these three domains is concerned with rRNA, cell membrane lipid structure, and the sensibility to antibiotics. Prokaryotes includes members of bacteria and archaea while eukaryotes contain organisms that belong to the eukarya domain. For this compare and contrast we will only focus on two domains which are archaea and bacteria domains.

1.Cell theory just give a description of a cells. Like all living things are made up of cells individually. Also describes how cells can reproduce and metabolize by themselves; which means that they are living small organisms. Germ theory just clarifies on how these microbes are responsible for the infectious diseases that enter the body.

The theory of Endosymbiosis originated in the early 1900s by the Russian botanist, Konstantin Mereschkowski.1 The Endosymbiont theory states that organelles of eukaryotic cells came from prokaryotic cells that had been swallowed by them and survived by developing a symbiotic relationship, two different entities working together to benefit each other, by living inside the larger cell. Scientists have conducted extensive research and believe that mitochondria, chloroplasts, flagella, and microtubules have all originated from prokaryotes derived from the theory of Endosymbiosis. Many examples of endosymbiotes can be seen all throughout the world. The most common can be seen as unique bacteria living inside the digestive system of many different

Interestingly, identical elements are also found to be part of A. Castellani genome suggesting a route for gene transfer either from prokaryotes via giant viruses or from protoeukaryotic ancestors [93]. These elements can manipulate the downstream gene expression [94] and play a major role in gene inactivation, deletion, duplication and genetic rearrangement in the genome via homologous/illegitimate recombination [34]. In an extreme case, about 30 non-autonomous transposable elements commonly known as MITEs (10 are integrated in the coding regions) have “colonized” [95] the genome of Pandoravirus salinus, but were undetectable in Pandoravirus dulcis [95]. Akin to their role in prokaryotes, they promote gene deletion and genetic rearrangement [96]. A conceivable outcome of such genome plasticity would be the loss and/or gain of function, accelerating host-switching and adaptation. Apart from these family-specific mobile elements, the genomes of NCLDV also contain self-splicing introns [97] and inteins along with HNH endonuclease which might aid in the mobility of genetic elements [98]. All three are known to influence genome evolution in all forms of life through their splicing and nuclease activity

Some the evidence for this theory include the mitochondria and plastids which can be identified in a eukaryot; however, prokaryotes originally also have the same functional capabilities as the mitochondria, as well as plastids. Perhaps the mitochondria’s development is simply a result of condensing the process of energy creation into a single organelle and the development of plastids was a result of prokaryotes also being capable of completing a similar task; however, felt the need for condensing this task into a single