Endosymbiont Theory Mitochondria And Chloroplasts Biology Essay

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Although resource wars have been going on throughout mankind history, competition has entered into an extraordinary phase. Human are more likely to desperately seek for resources due to the earth's climate instability and natural resources scarcity. This might increase conflicts within different countries in developing world. Many wars within nations, mostly world's poorest countries have occurred since 1945 (End of World War 2). Civil conflicts destroy poor nations by damaging the vital infrastructure, aggravating existing food shortages, and spreading disease and diverting scarce resources toward military spending.

The most prominent problems faced by developing countries are food shortage and malnutrition. A cooperative strategy is at least theoretically feasible, and its foundations already exist in nature and with rapid advancement in scientific research it can be used to solve or minimise the global food scarcity.

The most prominent example in nature can be found is of the sea slug, Elysia chlorotica (Fig. 1) is considered partial plant as it manufactures chlorophyll. It is an animal known for capturing the photosynthesizing organelles and genes from Vaucheria litorea (algae). Another example is the giant clam; it stores symbiotic zooxanthellae (a single-celled algae) in its fleshy body. The clam faces the shell opening towards sunlight and the zooxanthellae share food with the clam through photosynthesis as a form of mutual symbiosis.


As stated in the endosymbiont theory, mitochondria and chloroplasts are the products of evolution begun by the endocytosis of bacteria and blue-green algae. Instead of becoming digested, they contribute to the host cell. On the other hand, chloroplasts might be ingested by selective eukaryotic cells after the first mitochondrion. This explains why most eukaryotes have mitochondria but only few have chloroplasts. Some eukaryotic cells ingested smaller prokaryotic autotrophic cells. These cells have the ability to convert the sunlight energy into the food source by fixing carbon (into simple sugars. The host cells gave these prokaryotes inorganic compounds like CO2 and safeguard them from the environment. Both mitochondrion and chloroplasts are interdependent and they transform into organelles of the host cell.

The facts of the symbiotic theory are discovered in various sources. Mitochondrial and chloroplast DNA is both circular and duplicates are present in every organelle, like prokaryotic cells. Their organelles have ribosomes and enzymes that are more related to prokaryotes than eukaryotes. Endosymbiosis is supported by the fact that each organelle has its own plasma membrane. Lastly, mitochondria and chloroplasts reproduce themselves independently of the cell. Many proteins that chloroplasts need to function could be found in genomic (nuclear) DNA.

In human beings research done with the burn victims can be used to conduct the pilot study and it might be feasible to add skin stem cells with the required genes to be applied as a skin graft. This methodology should be feasible for producing sugar by photosynthesis by human as it was used to produce proteins in mice (Larcher et al, 2001). This graft might require regular replacement initially because of immune system restrictions but the chloroplasts will be sustainable within the skin eventually due to genetic and natural adaptation.

In order to incorporate chloroplasts with human, we will have to genetically modify ourselves to express proteins vital for the chloroplast function. The plant's genome provided about 70-90% of the genes required for the chloroplast function (Martin et al, 1998).

Positive impact

If human skin can incorporate plant chloroplasts, there will be unlimited benefits to the ecosystem.

human will be less destructive to the ecosystem and balance can be restored to food chain as we will be less dependent on plants and animals as a source of food.

Significant increase of food prices in the last decade which has been devastating to those with only a few dollars a day to spend. It has been estimated 925 million people is 13.6 percent of the estimated world population of 6.8 billion are undernourished are in developing countries. It will help significant percentage of this population for feeding purpose.

We can be a lesser threat to endangered animal as many are being hunted down for their meat as well as other economical and health benefits. (e.g. Bluefin Tuna, Fin Whale, etc).

Negative impact

Plants and animals have very distinct types of DNA and RNA. However, there are also eukaryote single cells creatures (e.g. phytoplankton) which are crossover species. There are some chemicals which are required by chloroplasts which human body cannot process. Hence, incorporating plant chloroplasts with human skin do have numerous challenges, such as:

Our immune system might attack the chloroplasts. However, they might be safe from antibodies if they stay inside the cells as the immune system will only attack mitochondria if they are present in the blood.

The ultraviolet component from sunlight can cause great damage to human's skin. Humans produce melanin to protect against harmful light rays. Plants and algae produce screening compounds instead but absorb most of sunlight. There will be a challenge for the skin to block the penetration of the sunlight.

A plant has a large surface area to absorb the sunlight and the giant clam uses its extensive mantle to increase surface area exposed to the light. For a human, we need to have a greater surface area to expose to the sunlight to drive the photosynthesis as we require more energy per day compared to plants.

The reaction of photosynthesis can be simplified as the following:

6 CO2(g) + 12 H2O(l) + light → C6H12O6(aq) + 6 O2(g) + 6 H2O(l)

The formulae represent that for every glucose molecule produced; there will be a loss of six water molecules. Hence, a plant-person (symbiosis algae-person) needs more water than a normal human. This could pose an issue for a plant-person living in a desert environment and exploitation of fresh water resources.

It will be a challenge to handle large amounts of sugar in our body tissues and fluids. It could overwhelm the ability of the liver to metabolize. The excessive sugar could cause water and electrolyte balance in the body to change. The excess sugar would be excreted by the kidneys so it would be wasted energy.


There are limitations and ethical concern for the human genetic engineering researches. Genes influence health, human traits and behaviour. Genetic technologies are used by researchers to unravel the genomic contributions to these different phenotypes and potential applications and desired traits can be induced for future.

One concern of these researches is the fear that those people who do not possess the genes for a positive trait may develop a negative self-image and/or inferiority complex leading up to group formations and rivalry. Another matter bioethicists often consider is that people may discover that they carry some genes associated with physiological or behavioural traits that are frequently perceived as negative. Moreover, many critics fear that the prevalence of these traits in certain ethnic populations could lead to prejudice and other societal problems. Thus, rigorous social science research by individuals from diverse cultural backgrounds is crucial to understanding people's perceptions and establishing appropriate boundaries.