Bacterias are believed to be among the oldest cells on Earth, fossils indicate bacteria-like beings were about about 3.5 billion old ages ago. They are unicellular microorganisms that lack a membrane edge karyon and contain no cell organs. Many people consider them to be the cause of many diseases, which they are, but the human organic structure contains millions of bacteriums, helping procedures such as digestion and growing. Mitochondria on the other manus are cell organs found in the bulk of eucaryotic cells, they produce energy in the signifier of adenosine triphosphate ( ATP ) . What could these cell organs found in eucaryotes have in common with bacteriums, which are procaryotes? Hopefully this essay will turn to that inquiry and effort to reply it. To accomplish this in the first subdivision of this essay I will see the structural similarities between them both. I will so travel on to compare the functional similarities in the 2nd subdivision of this essay which will so be followed by a subdivision sketching and explicating the endosymbiotic theory which should assist to clear up the old subdivisions. Finally I will summarize the similarities between chondriosomes and bacteriums and the causes of these similarities and the cogency of the theory explicating them.
Structure
At first glimpse bacteriums and chondriosomes look to hold a really different internal construction and can besides hold a radically different external form, but inside they do portion some similarities. The internal construction of bacteriums is really simple, it contains no membrane edge cell organs, but alternatively it contains a nucleoid which is the cardinal portion of the cell and it is where the Deoxyribonucleic acid is by and large confined to. Ribosomes are present in the cytol of the bacterium every bit good as storage granules. All bacteriums have a plasma membrane, most besides have a cell wall and while some have a capsule, others do non ( 1 ) . Some bacteriums besides have scourge which are bantam whip-like constructions frequently located at one terminal of the cell. Although they vary in size greatly, common bacteriums such as Escherichia coli are about 2?m in length, when comparing this to mitochondria they are really similar in length but like bacteriums, the forms and sizes of chondriosomes vary significantly depending on what species or cell they are found in ( 2 ) .
Mitochondrions are located in the cytol of both carnal and works cells ; they are cylindrical constructions that consist of an outer membrane, interior membrane and matrix. Like bacteriums, chondriosomes besides have their ain round DNA genome which is separate from the karyon of the cell which is located in the matrix. The membrane of the chondriosome is besides really similar to the membrane found around the bacterium ; it is dual superimposed and is made up from lipoids, merely like a procaryotes membrane. This is interesting as it shows no similarities with a eucaryotic cell ‘s cytol, but alternatively it is really similar to the composing of a bacterial membrane. The interior creases of the mitochondrial membrane, cristae, are really similar to mesosomes found in bacteriums. Mitochondria besides contain ribosomes similar to those found in bacterium ; this will be explained further in the following subdivision.
Function
The chief map of bacteriums, like any being, is to reproduce, and while chondriosome ‘s chief map is to bring forth energy in the signifier of ATP it besides needs to reproduce. Mitochondria are formed by a procedure really similar to binary fission, the method by which bacteriums divide. When a bacteria reaches a certain size, it splits down the center to make two beings. In a chondriosome the karyon signals the cell to bring forth more cell organs, but merely the chondriosomes really replicate themselves while other cell organs have to be made up from substances present within the cell. There is an electron conveyance concatenation found in both the plasma membrane around a procaryote every bit good as in the membrane around the chondriosome but it is absent in membrane of eucaryotic cells.
Proteins are required in a cell to execute all maps and all synthesis of these proteins takes topographic point in ribosome ; these ribosomes are present throughout the cell but chondriosomes have their ain ribosomes to bring forth the proteins they need. Chemical and microscopic analysis shows how the constructions of mitochondrial and bacterial ribosomes portion more similarities with each other than with ribosomes in eucaryotic cells. Ribosomes found in the cytol of eucaryotic cells are 80S in size while ribosomes found in bacteriums and chondriosomes are 70S in size ( 3 ) . One experiment carried out by Margulis showed that the protein synthesis of both chondriosomes and bacteriums are sensitive to erythromycin and chloramphenicol and insensitive to cyclohexamide and emetine whilst cytoribosomal protein synthesis is insensitive to erythromycin and chloramphenicol and is normally sensitive to cyclohexamide and emetine, proposing that mitochondrial ribosomes are different from those found in the cytol of eucaryotic cells, and are similar to those found in bacterium. This experiment among other structural and functional similarities lead to Margulis to explicate the theory of endosymbiosis.
Endosymbiosis
The theory of endosymbiosis had been around before the grounds published by Lynn Margulis, but it was her work that made it a widely accepted theory among life scientists. Included in her hypothesis was the idea that chondriosomes are the consequence of endocytosis of aerophilic bacteriums. This would explicate the similarities between chondriosomes and bacteriums, and why chondriosomes differ from what would be expected from a typical eucaryotic cell organ. The theory purposes that a proto-eukaryotic cell ingested an aerophilic bacteria but it failed to digest it. The aerophilic cell so thrived due to the cell ‘s cytol being full of partly digested nutrient molecules, and some of the ATP may hold leaked into the cell ‘s cytol. This occurred around a clip where the concentration of O in the ambiance was increasing and aerophilic respiration was advantageous to last ( 3 ) . An addition in ATP must hold caused a growing advantage to the proto-eukaryote, enabling it to rule over other cells that lacked cell walls and endosymbionts. The endosymbiont, originally the aerophilic bacteria, finally became dependent on the host for both protection and foods, intending there was small demand for cistrons involved in these procedures. On the other manus, due to the endosymbiont merely being permitted to stay if it continued to capture and hive away energy, there was a strong selective force per unit area to retain the cistrons involved in energy gaining control and storage. Eventually cistrons whose merchandises were of no usage to the host eroded and were finally lost. Finally as the genome decrease continued, the endosymbiont evolved into an energy-providing cell organ. However, some more recent research suggests that the endosymbiont may hold been an anaerobiotic bacteria with a fermentative metamorphosis ( 4 ) . The bacteria that was originally engulfed is believed to hold evolved into a chondriosome that enabled the development of larger beings.
The endosymbiotic theory is good supported, although there are many different fluctuations of it there is strong grounds that suggests chondriosome did arise from bacteriums. The similarities in the old subdivisions are all grounds indicating towards endosymbiosis and this theory explains why bacteriums and chondriosomes have much in common, and why the chondriosome ‘s map and construction frequently defies what would be expected from a eucaryotic cell organ.
Decision
The similarities between bacteriums and chondriosomes are easy to see despite belonging to different spheres. When a chondriosome is looked at in item there are obvious differences to a eucaryotic cell and other cell organs present in the eucaryotic cytol, the biggest of these is possibly the presence of mitochondrial DNA, but there are similarities in many other facets of a chondriosome. Their primary maps may be different but bacteriums and chondriosomes still portion procedure such as binary fission. All this grounds leads to the endosymbiotic theory which offers an account for these similarities, although many parts of it are still being debated. This theory allows us to understand how individual cell beings developed into the huge array of complex beings that are present 3.5 billion old ages after the first bacteriums are thought to hold existed.
