Saturday, October 19, 2013

Evidence of the Endysymbiosis Theory

Research what the Endosymbiosis Theory is and summarize it.  Provide four pieces of evidence used to support it and explain the evidence so your audience can understand it. 

7 comments:

  1. The theory of the endosymbiosis explains the origin of chloroplasts, mitochondria and their double membranes. The theory explains that chloroplasts and mitochondria are the result of years of evolution started by endocytosis of blue-green algae. Blue-green algae were not digested but became symbiotic instead. (Having an interdependent relationship)

    The theory says that several organelles of eukaryote's came as symbioses between separate single-celled organisms. Mitochondria and plastids like chloroplasts and possibly other organelles represent free-living bacteria that were taken inside another cell as an endosymbiont (something that lives inside the body of a host).

    The mitochondria takes oxygen to extract energy from carbon sources like glucose, making carbon dioxide and water in the process. The chloroplast takes water and carbon dioxide as it takes energy from light and puts it into the chemical energy of glucose, releasing oxygen in the process. Organelles were once prokaryotic cells, living inside larger host cells. The prokaryotes may first have been parasites or even an intended meal for the larger cell, somehow escaping digestion.

    Sources:
    http://biology.kenyon.edu/HHMI/Biol113/the%20endosymbiotic%20theory.htm
    http://en.wikipedia.org/wiki/Endosymbiotic_theory
    http://www.dummies.com/how-to/content/endosymbiotic-theory.html


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  2. “Her hypothesis originally proposed that: 1) Mitochondria are the result of endocytosis (cell eating) of aerobic bacteria, 2) Chloroplasts are the result of endocytosis of photosynthetic bacteria, 3) Both cases the aerobic bacteria and photosynthetic bacteria’s endocytosis were by anaerobic bacteria who would not be able to live in aerobic environment and 4) This arrangement became a mutually beneficial relationship for both cells (symbiotic).” (IUPUI University, 2002). The endosymbiotic theory states that all organelles in a eukaryote cell were once separate microscopic objects. Lynn Margulis first stated this theory. It states that eukaryote cell “ate” the other free-living organisms (the organelles) and they became part of the cell. In other words, mitochondria and chloroplasts and possibly various other cells were once free-living bacteria-like “critters”, but were taken in by eukaryote cells and became endosymbiont (organisms that live inside any other cell). An example of endosymbiont organisms is rhizobia, which is a nitrogen-fixing bacteria (bacteria that “converts” nitrogen in the atmosphere to ammonia), whose “products” are necessary for all life forms to make more complex products of building blocks of their organisms (biosynthesize). Basically, organelles that now appear on the eukaryote cell and help out with its processes, were once free-living bacteria-like organisms that were taken into eukaryote cells and from then were transformed to adapt to their new “environment”, which is the eukaryote cell. The organelles that were taken into the cell were especially the mitochondria and the plastids. An example of plastids is the chloroplasts. In even simpler words, it’s just like symbiosis, where two species live together and one gains something positive off or from the other, but one is living inside the other.

    There is also evidence that help this “building” keep standing. For example, mitochondria and chloroplasts have their own DNA. There is also other evidence that proves this theory, which is the timeline of Earth. “ 1) Anaerobic bacteria: Scientists have fossil evidence of bacterial life on Earth ~3.8 billion years ago. At this time, the atmosphere of Earth did not contain oxygen and all life (bacterial cells) was anaerobic. 2) Photosynthetic bacteria: About ~3.2 years ago, fossil evidence of photosynthetic bacteria, or cyanobacteria, appears. These bacteria used the sun’s energy to make sugar. Oxygen, released as a byproduct, was starting to accumulate in the atmosphere. (…) Anaerobic bacteria were at a disadvantage in an oxygen-containing atmosphere, and started to die out as oxygen levels increased. (…)” (IUPUI, 2002) The chloroplasts and mitochondria divide by binary diffusion, something very characteristic of bacteria.



    Bibliography

    Yahoo Answers
    http://answers.yahoo.com/question/index?qid=20100613231615AAtefbG

    IUPUI University, Department of Biology
    http://www.biology.iupui.edu/biocourses/N100/2k2endosymb.html


    Wikipedia
    http://en.wikipedia.org/wiki/Endosymbiont
    http://en.wikipedia.org/wiki/Nitrogen-fixing
    http://en.wikipedia.org/wiki/Symbiosis

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  3. “The endosymbiotic theory states that, several key organelles of eukaryotes originated as symbiosis between separate single-celled organisms. –Wikipedia” This theory was first suggested in 1883 by scientist Andreas Schimper, he looked at the possibility studied and described it. Since then it has been resurfacing and being studied again and again by different scientists. The scientist that made the most impact with her explanation of the theory in 1981 was called Dr. Lynn Margulis. There have been many examples of this theory all throughout nature.

    The theory also states that eukaryotic cells arose using endosybiosis. Some examples of the endosymbiotic theory are; the relationship of coral and the algae Symbiodinium, the way it works is the coral uses its cells to photosynthesize. Another real life example of endosymboisis is the clown fish and the anemone. They work together so the clownfish can enter and live in the anemone as they please, this is due to certain mucus they contain on their skin protect them from getting burnt.

    Endosymbiosis is primarily when the chloroplast and the mitochondrion enter a cell and live within it, thus making it a eukaryotic cell. In simpler words, it is when a living cell enters within the body of another living cell. There are also other forms of endosymbiosis like secondary endosymbiosis which is when a cell that has already gone through the process once undertakes it once and again for example, brown algae.

    Sources:
    • http://en.wikipedia.org/wiki/Endosymbiotic_theory - “Endosymbiotic Theory”, Wikipedia, (last updated) October 22nd 2013.
    • http://biology.kenyon.edu/HHMI/Biol113/the%20endosymbiotic%20theory.htm - “The Endosymbiotic theory”
    • http://simple.wikipedia.org/wiki/Endosymbiosis - “Endosymbiosis”, Wikipedia, (last updated) March 16th 2013.
    • http://endosymbiotichypothesis.wordpress.com/history-the-formation-of-the-endosymbiotic-hypothesis/ - “The Endosymbiotic Hypothesis”
    • http://www.asknature.org/strategy/fb410d8500af30a5daf5b647954b7fa5 - “Relationship Protects from Predators: clownfish, anemones” ©2008- 2013
    • http://www.youtube.com/watch?v=-FQmAnmLZtE - Mr. Anderson, November 2nd 2012.

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  4. Although the Endysymbiosis Theory can seem confusing originally, once you study it throroughly, it is a very interesting and simple theory to learn about. The theory’s main idea is that mitochondria and chloroplasts are believed to have developed from symbiotic bacteria (bacteria living in symbiosis with another organism or each other) and, more specifically, cyanobacteria (a bacteria that obtains its energy through photosynthesis). The theory also states that a prokaryotic organelle may have been consumed a larger, different organelle. By some unknown reason, the prokaryotic organelle was not consumed. This lack of consumption would later lead to both cells forming a mutualism (two organisms of different species exist in a relationship in which each individual benefits receiving surviving benefits from each other). Over time, the newly combined organelle would develop into the complex eukaryotic cell of today. The endosymbiosis theory has been widely accepted as one of the possibilities of the origins of mitochondria, chloroplasts, as well as other eukaryotic organelles and cells.
    The Endysymbiosis Theory is mainly about the origins of mitochondria and chloroplast, which are organelles of eukaryotic cells. According to the theory, these originated as prokaryotic endosymbionts (organisms that live within the body or cells of another organism), which came to live inside eukaryotic cells. The theory suggests that the mitochondria evolved from aerobic bacteria and chloroplast evolved from endosymbiotic cyanobacteria.
    There are four pieces of evidence that support the theory, the first being that both mitochondria and chloroplasts contain DNA, which is fairly different from that of the cell nucleus, in a quantity similar to that of bacteria. The next piece of evidence is Mitochondria and chloroplasts are similar in size and morphology (form) to bacterial prokaryotic cells. Then, the ribosomes are bacterial ribosomes (different from the ribosomes of the cell that they are in). Lastly, they have their own plastid genomes (same as what bacteria have). Based on the evidence provided, it is obvious to tell that the Endysymbiosis Theory is real.

    Resources:
    “Endosymbotic Theory”: October 22, 2013
    http://en.wikipedia.org/wiki/Endosymbiotic_theory


    “Endosymbotic Theory for Dummies”: February 2013
    http://www.dummies.com/how-to/content/endosymbiotic-theory.html

    “The Endosymbotic Theory”: December 2012
    http://biology.kenyon.edu/HHMI/Biol113/the%20endosymbiotic%20theory.htm

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  5. The theory of endosymbiosis explains the origins of chloroplasts and mitochondria and their double membranes. The concept says that chloroplasts (Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis (1). And mitochondria are years of evolution that started with the endocytsis of bacteria and blue-green algae. Endocytosis is when a substance gains entry into a cell without passing through the cell membrane (2).

    Endo means within and symbiosis means together. There was once a long time ago Aerobic Bacterium which did cellular respiration, which means breaking down food in the presence of oxygen. There was also Cyanobacterium which were doing photosynthesis and they were engulfed by another host cell and became mitochondria and chloroplast which we can find today. These cells became part of one cell and eventually became that cell. The mitochondria that are found inside our cells are like hijackers that have been in our cells for billions of years.

    One type of coral is able to do photosynthesis but coral is an animal. The coral has algae called Symbiodinium and it is a type of dinoflagellate. The dinoflagellate is eaten by the coral, so the coral is taking in these algae. The coral does not break down the algae, the algae lives within the coral. The algae are producing food through photosynthesis. The food is then taken in by the coral and in return the coral is giving it a place to live. Scientists believe that this created the first eukaryotic cells.

    The evidence that scientists have is that there is a type of bacteria that looks a lot like mitochondria and have a lot of similar properties. There membranes are also very similar. Mitochondria have double membranes and so does the bacteria. The way that they reproduce is also very similar. For mitochondria to reproduce they copy their chromosomes, and the chromosomes line up in the middle and then It divides in half and that process is called mitosis. Bacteria copy their DNA then they just pinch in half and that process is called binary fission. In our cells mitochondria are making copies of themselves through asexual reproduction which looks a lot like asexual reproduction in bacteria. Now scientists are able to compare the DNA in these prokaryotic cells and mitochondria. Mitochondria have their own DNA; they are like cell within our cell. This is one of the ways cells became eukaryotic. (3)


    1. http://www.sciencedaily.com/articles/c/chloroplast.htm
    2. http://biology.kenyon.edu/HHMI/Biol113/the%20endosymbiotic%20theory.htm
    3. http://www.youtube.com/watch?v=-FQmAnmLZtE

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  6. The endosymbiosis theory explains the origin of chloroplast and mitochondria and their double membrane. Biologist Lynn Margulis first made the case for endosymbiosis in the 1960’s, but for many years other biologists were skeptical about her theory. Now there is compelling evidence that mitochondria and chloroplasts were once primitive bacterial cells. This evidence is described in the endosymbiotic theory. How did this theory get its name? Symbiosis occurs when two different species benefit from working and living together. When one organism lives inside the other organism it is called endosymbiosis. The endosymbiotic theory describes how a large host cell and ingested bacteria could easily become dependent on one another for survival, resulting in a permanent relationship. Over millions of years of evolution, mitochondria and chloroplasts have become more specialized and today they cannot live outside the cell.1
    We have now found many lines of evidence supporting the idea of the endosymbiosis theory. The first evidence supporting the theory is that mitochondrion has its own cell membrane, just like a prokaryotic. The second evidence supporting the theory is that each mitochondrion has its own circular DNA genome, like a bacteria’s genome, but much smaller. (A genome is an organisms complete set of DNA.)2 This DNA is passed from mitochondrion to its offspring and it is separate from the “host” cell’s genome in the nucleus. The third evidence supporting the theory is that mitochondrion multiply by pinching in half and the same process is used by bacteria. Every new mitochondrion must be produced from a parent mitochondrion in this way; if a cell’s mitochondrion is removed, it cannot build new mitochondrion from scratch.3

    Sources:
    1. Endosymbiosis Theory
    http://learn.genetics.utah.edu/content/begin/cells/organelles/
    2. Genome
    http://ghr.nlm.nih.gov/handbook/hgp/genome
    3. Evidence
    http://evolution.berkeley.edu/evolibrary/article/_0_0/endosymbiosis_04

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  7. The endosymbiosis theory is a theory explaining the source of chloroplasts and mitochondria and their double membranes (Bethany Lye). Symbiosis happens when two different species profit from living and working together like partners. The endosymbiosis theory is basically providing more information of that. This theory is explaining how organisms can depend on each other and build a promising relationship between each other. It also states that blue green algae and bacteria were not digested instead they became symbiotic. (Paula Millington, The University of Utah).
    The originator of this theory was an evolutionist named Lynn Margulis. She studied the structure of cells. She discovered a correlation between mitochondria and bacteria. Chloroplasts and mitochondria resemble a lot to bacteria. Scientists began proposing that chloroplasts and mitochondria evolved from bacteria. They wanted to discover even more about this theory and back it up with concrete evidence.
    Two microbiologists, Carl Worese, and W. Ford Doolittle compared the genes on the inside of chloroplasts and some species of algae. The scientists discovered the genes of the chloroplast were similar to the algaes nucleus. The result was that chloroplast DNA was cyanobacterial (David. H Walker and Vsevolod Popov).
    There has been a lot of evidence found to back up this theory. The first piece of evidence is mitochondria and chloroplasts divide by binary fission, and bacteria do as well, unlike eukaryotes that divide by mitosis. The second piece of evidence is they both produced their own ribosomes. The third piece of evidence is the organelles ribosomes are similar in size to prokaryotic cells. The final piece of evidence is mitochondria and chloroplasts have their own DNA and their own ribosomes (http://endosymbionts.blogspot.com/2006_12_01_endosymbionts_archive.html)

    Sources:
    1. "THE EVOLUTION OF THE CELL." The Evolution of the Cell. N.p., n.d. Web. 25 Oct. 2013.

    2. "Endosymbiosis: Lynn Margulis." Endosymbiosis: Lynn Margulis. N.p., n.d. Web. 25 Oct. 2013.

    3. "The Endosymbiotic Theory." The Endosymbiotic Theory. N.p., n.d. Web. 25 Oct. 2013.

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