Do endosymbotic relationships still exist today?

Answer original forum 300 words minimum 

Respond to both class mates 100 words minimum 

Follow directions or I will dispute 

original forum – page 1 with references 
student response – page 2 with references 
student response – page 3 with references 

Original Forum

There are fundamental differences between the two types of cells but also similarities. An interesting concept in science is that prokaryotic cells are what gave rise to eukaryotic cells via an endosymbiotic relationship. The two primary examples of this are the mitochondria in animal cells and chloroplasts in plant cells that are very similar to bacteria.

Review the information available at Endosymbiosis and The Origin of Eukaryotes

Once you have reviewed this information, choose ONE of the topics below
Topic 1: Animal cell mitochondria 
Topic 2: Plant cell chloroplasts
Research and Support your post to address the following questions in your initial post in an expository manner;

If you chose animal cells, how are mitochondria replicated within eukaryotic cells?
If you chose plant cells, how are chloroplasts replicated within plant cells?
How are these processes similar to microbes?
Do endosymbotic relationships still exist today?
What are the advantages and disadvantages of such relationships?

Student response


Good evening class,
From the information that we have been reading about this week, there is a lot to take in and especially trying to understand the prokaryotes and eukaryote relationships. According to the endosymbiotic theory proposed by Lynn Margulis more than 50 years after it was proposed, it was found that mitochondria and chloroplasts originated from prokaryotic organelles due to their “symbiotic relationship within a eukaryotic host” (Parker, 2016). After the theory was widely accepted, she wrote a book and in it explained how endosymbiosis is a huge part of evolution. Prokaryotes arose from eukaryotes with this relationship from the mitochondria. From what I gathered, it sounds like the mitochondria of the prokaryotes find duplicate in the cells of the eukaryotes as its host.
The similarities between this and microbes can be seen through its replication. Throughout its discovery, scientists learned that mitochondria has its own genome and ribosomes. This means that it is capable of its own cellular respiration. These bacterium were taken over by phagocytosis into a host cell where it remained (Parker, 2016). In terms of similarities, microbes have the same behavior when they attach themselves to a host. They remain to have a symbiotic relationship in which the host benefits from its presence, is harmed, or neither of the two.
Endosymbiotic relationships still do exist today as they are part of evolution. As we know, this kind of relationship involves one cell not being able to live without another. We can see this kind of behavior with bacteria. It has been around for millions of years and has learned to adapt itself in order for it to reproduce. Through the use of transformation, they are able to pick up DNA from the surrounding area and transform it to its own (APUS Lessons, 2018). These kinds of relationships are advantageous because cells are able to produce with the help of another cell. However, it is also its downfall. If those cells are not available, an endosymbiotic relationship will not be possible. Without having something to depend on for survival, the evolution of the cell may never be accomplished and thus cease to eventually exist.
APUS Lessons. (2018). Lesson 2. Retrieved October 9, 2018
Parker, N. (2016). Microbiology. OpenStax. Retrieved 2018


Mitochondria and chloroplasts do not divide my mitosis like other cells in the body, but by fission.  Mitochondria come from other, established mitochondria; they have their own unique circular shaped DNA, attaching to the inner membrane similar to the DNA of prokaryotes.  The processes are similar to microbes in their resemblance of ribosomes and appearance.  Organelles have the same sized mitochondria, but different shapes, appearing it to be more rectangular.  The cellular shaped DNA loops around super coiled and doubly covalently linked, similar to DNA bacteria, however mitochondria that is ciliated appears more linear.  Endosymbotic theory still exist and has been built upon to include the suggestion that eukaryotic flagellum arose from an ectosymbiotic spirochete bacterium and prokaryotes living today are not known to have another prokaryote living inside (Origin of Eukaryotes, n.d.) 
            I believe endosymbiosis is an explanation of not only what happened between microbes in the past but also what happened today with different types of organisms, termites are just one example of how prokaryotes live within them in order to help digest wood.  Studies arguing how “unique microbial consortium living in the guts of lower termites is essential for wood-feeding, host and symbiont cellulolytic enzymes synergize each other in the termite gut to increase digestive efficiency” (Peterson & Scharf, 2016).  Bacterial groups in a termite’s lower gut have diverse metabolic methods including acetogenesis, nitrogen fixation, and degradation of lignin phenolics.  Though termites are able to digest nitrogen poor wood and digest it, this microbe rich environment makes them vulnerable to pathogenic infections. 
Origin of Eukaryotes (n.d.). GW. Retrieved from
Peterson, B. F., & Scharf, M. E. (2016). Lower termite associations with microbes: Synergy, protection, and interplay. Frontiers in Microbiology, 7, 422. doi:10.3389/fmicb.2016.00422

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