The theory of endosymbiosis

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  1. Terms like “eukaryotic cell” and “prokaryotic cell” are important in biology. Among other differences, eukaryotic cells have organelles while prokaryotic cells don’t, but several important organelles found within eukaryotic cells actually resemble prokaryotic cells.

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In the this weeks discussion, you are to describe the theory of endosymbiosis as proposed by Lynn Margulis;

Please watch the videos found at and

(1) Describe the theory in general terms;

(2) Describe what chloroplasts and mitochondria produce in eukaryotic cells (the specific chemical that is produced by electron transport systems in both cases),

(3) provide three details from cell biology that support the theory.

  1. Respond to the following posts
  2. The theory is that eukaryotic cells derived from interactions between various “entities, including spirochaetes” (spiral-shaped bacteria) which mutated into flagella (a lash-like feature used for locomotion and sensing chemicals or temperature) and cilia (hair-like structures that contribute to locomotion and mechanoreception) (“Endosymbiotic theory”). The former part of the theory became widely accepted while the latter has been questioned more because “flagella lack DNA” and also bear no “ultrastrucural similarities to prokaryotes” (“Endosymbiotic theory”). The mitochondria in eukaryotic cells produce ATP molecules, while chloroplasts produce chlorophyll.Supporting evidence includes mitochondria and chloroplasts carrying DNA that better resembles that of bacteria than that of the cell nucleus. It also includes mitochondria using a distinctly different genetic code from that of the cell in which it resides, and which more closely resembles bacteria. It also includes the fact that they are “surrounded by two or more membranes,” the interior of which is unique and separate from the cell’s other membranes, and more closely resemble prokaryotic membranes (“Endosymbiotic theory”). These examples form a sort of “missing link” that reinforces the notion of a development through networking or interaction. It brings to mind other developmental/evolutionary discoveries that birthed or reinforced theories, including the archaeopteryx and the theory of Pangaea being derived from/supported by similarities in plants, animals, and geological formations in regions formerly united by the landmasses in question. The evidence is compelling and the theory derived from it seems intuitive and logical.
  3. Describe the endosymbiosis or endosymbiosis theory in general terms:
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According to San Jose Science, Technology, and Society (n.d.), Dr. Lynn Margulis stated in her endosymbiosis theory that mitochondria and chloroplasts were once prokaryotic organisms that merged with eukaryotic cells. These prokaryotes formed a symbiotic relationship with the host eukaryotic cells which is the catalyst to evolution (History section, paras. 1 – 2).

  1. Describe what chloroplasts and mitochondria produce in eukaryotic cells:

Chloroplasts and mitochondria produce adenosine triphosphate (ATP) in eukaryotic cells, which provides energy for all cell activities during cell respiration (Nucleus Medical Media, 2015).

  1. Provide three details from cell biology that support the theory:

Mitochondria and chloroplasts have their own DNA that are closely related to prokaryotes (Warring, 2016). Mitochondria and chloroplasts have their own ribosomes. Mitochondria and chloroplasts are the same size as prokaryotes (Kaiser, 2020).

Discussion Post: 102

  1. (2) describe the structure and specific functions of a plasma membrane that surrounds every cell and provides the cellular boundaries.

(7) Osmosis is a very important cellular function that involves water. First explain what it means.

3) A Tour of the Cell- watch and comment after the video


Last Updated on November 6, 2020 by EssayPro