What Is Serial Endosymbiotic Theory? How did cells develop from simple to complex? Mitochondria and chloro

[unicornrose 0]

I am not sure how many people are familiar with cells and biology. I wanted to share something that I researched for a class. I am in a botany class and one of the things we had to do for our class is an evolution project. We could do it on anything at all. I have always been facinated by mitochondria. For those of you that do not know mitochondria are small organelles in our cells. They are the power house of the cell. They create and convert food particles for simplicities sake into ATP which is our main energy source for the things we do. For example I am using tons of ATP just typing this little post. :lol:Now just to give you an idea there are two types of cells. There are Prokaryotic and Eukaryotic. Prokaryotic cells do not have a nucleous. They have DNA in a circle but they do not have a nuclear envelop. These cells are mostly unicellular, but they can live in colonies and occationally they are also multicellular. This is important so please keep this in mind. It is believed that on an evolutionary scale prokaryotic cells evolved first. The second type of cell is the eukaryotic cell. It has a nucleus with a nuclear envelop. There are alot of organelles and things as well that make it way more complex than the prokaryotic cell. You can put prokaryotic and eukaryotic cell in the search engine and find some pictures if you are really interested. Well anyway the Serial Endosymbiotic Theory was postulated based on studies of both prokaryotic and eukaryotic cells. Two of the main organelles that have facinated biologists and bontanists is the mitochondria and chloroplasts. The reason why is they are very simular to prokaryotic cells. What is also interesting about both is they have their own DNA and they divide and reproduce without help from the cell they are living in. It is important to note they can not live on their own but its pretty clear they are like prokaryotic cells. So the theory is that Prokaryotic cells used to live in a vey harsh environment and were unable to make their own food so they had to engulf everything to get the nutrients they needed. Well when they were engulfing stuff sometimes they engulfed their fellow cells. The idea is that one or more of these fellow prokaryotic cells managed not to be digested by the cell but instead helped the cell out which cause the cell not to want to eat it. Basically a mutual symbiotic relationship was born. It is believed that the first cells that were engulfed were free-living bacterium that were evolutionarily very simular to the mitochondria we have today. The reason it is believed that mitochondria came first is all eukaryotic cells have mitochondria but not all eukaryotic cells have chloroplasts. Chloroplasts for those of you who do not know are the organelles that are unique to plants. They hold the chlorophyll which is the pigment that makes plants green. They also are inaugral to the photosynthesis process. There are other forms of chlorophyll besides the green kind. But because of the job that the chloroplasts do plants are able to make their own food and energy. Plants also have mitochondria. All complex organisims, plants and animals are a complex machine of eukaryotic cells.Its all very facinating.... I hope you think so too...

[Albus Dumbledore 0]

my question to you is what type of symbiotic relationship do they have?? muhahah lmao, can you answer that?!?! can ya can ya? hehe im joking! sorry im hyper! well this did advance my knowledge of cells and their purposes....lol thanx for posting it.i should go ask my biology teacher about this and see if se can tell me, maybe my A+ will turn to an A++ hehe! good thing you posted! keep up the good work

[ebula 0]

Basically a mutual symbiotic relationship was born. It is believed that the first cells that were engulfed were free-living bacterium that were evolutionarily very simular to the mitochondria we have today. The reason it is believed that mitochondria came first is all eukaryotic cells have mitochondria but not all eukaryotic cells have chloroplasts.

Chloroplasts for those of you who do not know are the organelles that are unique to plants. They hold the chlorophyll which is the pigment that makes plants green. They also are inaugral to the photosynthesis process. There are other forms of chlorophyll besides the green kind. But because of the job that the chloroplasts do plants are able to make their own food and energy. Plants also have mitochondria. All complex organisims, plants and animals are a complex machine of eukaryotic cells.

Its all very facinating.... I hope you think so too...

Well unicornrose, its good to have a biologist here atlest.

As you told about symbiotic theory, you forgot to mention the evidence on which the postulate is based on. Its the ribosomal DNA or in short rDNA. All the species have unique rDNA sequences. Scientists found this fact serendipitously. They tried to sequence rDNA from chloroplast as well as mitochondria. They found it to match more to prokaryotes rather than being originated from their host cell. They also had unique and self-sufficient replication, respiration and food storage mechanisms. It was surprising. After maping the evolutionary tree from the DNA sequence, it was found that these two cellular organnelles were a replica of prokaryotic cells.
Therefore, it was 'assumed' (as there is no theory yet to confirm) that the mitochondria or chloroplasts had formed symbiotic relation with blue green algae and in the course of evolution were differentiated into modern eukaryotic cells. They helped algae in respiration and photosynthesis and in turn, algae protected them from invasion of fungi and harmful bacteria by releasing antibiotics.
This is not entirely an unique case. In root nodules of plants, nitrogen fixing bacteria follow the same symbiotic relationship. They fix nitrogen for plants using their enzyme system (which plants dont have or not too effective) and in turn take nutrients from cell sap.
In our body, the microbial flora, that we always think of getting rid of (by using antimicrobial soaps) protect us from pathogenic invasion. In turn they degrade sweat to find their food. (poor guys).
I personally feel, boys, who dont let themselves clean, often dont have pimples (a kind of infection by propionobacterium acne) but girls who wash their face 10 times a day are always prone to get pimples.
This is a good example of symbiotic relation of humans with microflora. Our body secretes 'sebum' a fluid, that keeps pathogenic organism at bay. But still it dont harm the bacteria already having symbiotic relation with the individual.

There is too much to discuss, provided someone is interested. Although Xisto has lots of good people, discussing quite a good subjects (than most of the forums where people keep posting rapidshare links: useless), biologists are, I feel rather not much comfortable with internet. Its hard to find them discussing.

'unicornrose', I formed a forum for research scholars and scientists, running at Xisto free accunt, if you are interested, please pm me. I'll send you link. Thanks Opaque to have such a good community work.
Edited March 5, 2006 by ebula (see edit history)

[Kioku 0]

In my own humble opinion, most theories of how things came to be are simply fascinating. Man kind ( mankind as one word? I have no idea ) has always been trying to figure out where everything came from, as it works in larger senses. It's just interesting that how random sequences of slight genetic change shallowed out and the surviving organisms are what they are today. From an evolutionary stand point, it can lead one to wonder what could have happened if everything happened slightly differently. Anyway, as I was saying..

I personally feel, boys, who dont let themselves clean, often dont have pimples (a kind of infection by propionobacterium acne) but girls who wash their face 10 times a day are always prone to get pimples.

That's quite true, as I see this happen all the time in school.

[unicornrose 0]

my question to you is what type of symbiotic relationship do they have??

Mitochondria are the power houses of the cell. Basically they do the conversion of glucost to make the ATP that the cell uses to do work.

In our body, the microbial flora, that we always think of getting rid of (by using antimicrobial soaps) protect us from pathogenic invasion. In turn they degrade sweat to find their food. (poor guys).
I personally feel, boys, who dont let themselves clean, often dont have pimples (a kind of infection by propionobacterium acne) but girls who wash their face 10 times a day are always prone to get pimples.
This is a good example of symbiotic relation of humans with microflora. Our body secretes 'sebum' a fluid, that keeps pathogenic organism at bay. But still it dont harm the bacteria already having symbiotic relation with the individual.

Did you know also that we have bacteria that live in our intestional tract that help us digest some of the food we eat? I have always thought that was facinating too. I was not aware that there were bacteria that actually were beneficial to our bodies on the outside thuogh. I know that if you do not use deoderant then bacteria causes you to smell because of what its breaking down in the sweat. It all very interesting. You can get pimples without washing alot too. Depends on how oily your skin is. Plus women where make up and sometimes because of that the pores can not breath.