Both mitochondria and chloroplast have an inner and outer membrane, each a phospholipid bilayer with a unique collection of embedded proteins. The inner membrane of the mitochondria is convoluted, with infoldings called cristae which gives it a greater surface are to enhance productivity of cellular respiration, it also encloses the mitochondrial matrix, and contains built in enzymes that make ATP. The inner membrane of the chloroplast encloses the granum structures and stroma from cytosol. The majority of metabolic steps for both organelles occur in the mitochondrial matrix and stroma. Mitochondria are about 1 to 10 m long, and the chloroplast are about 2 m by 5 m in size.

Chloroplasts and Mitochondria generate ATP by the same basic mechanism: chemiosmosis. An electron transport chain assembled in a membrane translocates protons across the membrane as electrons are passed through a series of carriers that are progressively more electronegative. Built into the same membrane is an ATP synthase complex that couples the diffusion of hydrogen ions down their gradient to the phosphorylation of ADP. Some of the electron carriers, including quinones and cytochromes, are very similar in chlo

According to the endosymbiotic model, a hypothetical model of the origin of the eukaryotic cell, the forerunners of the eukaryotic cells were symbiotic consortiums of prokaryotic cells, with certain species, termed endosymbionts, living with larger prokaryotes. Developed most extensively by Lynn Margulis, the endosymbiotic model focuses on the origin of chloroplasts and mitochondria. Chloroplasts are postulated to be descendants of photosynthetic prokaryotes that became endosymbionts within larger cells. The proposed ancestors of mitochondria were endosymbiotic bacteria that were aerobic heterotrophs. Perhaps they first gained entry to the larger cell as undigested prey or internal parasites. By whatever means the relationship began, it is not hard to imagine the symbiosis eventually becoming mutually beneficial. A heterotrophic host could derive nourishment from photosynthetic endosymbionts. And in a world that was becoming increasingly aerobic, a cell that was itself an anaerobe would have benefited from aerobic endosymbionts that turned the oxygen to advantage. As host and endosymbionts became more interdependent, the conglomerate of prokaryotes would gradually be integrated into a single organism, its parts inseparable.

In considering the origin of eukaryotes, we must understand that the endosymbiotic model is not mutually exclusive. Possibly, the chloroplast and mitochondria may have originated as endosymbionts. In addition, the endosymbiotic model doesn't require an event leading to greater cellular complexity to happen just once in the course of evolution. Comparison of algal pigments and chloroplast construction suggests that, by whatever mechanism, photosynthetic protists likely evolved at least three times from separate prokaryotic ancestors.

The special organization of chemiosmosis also differs in chloroplast and mitochondria. The inner membrane o

Some common words found in the essay are:
Lynn Margulis, Chloroplasts Mitochondria, DNA Base-sequence, , Nass Nass, MtDNA Hitherto, chloroplast mitochondria, chloroplasts mitochondria, endosymbiotic model, atp synthase, inner membrane, ribosomal rna, hydrogen ions, transport chain, eukaryotic cell, eukaryotic cytoplasm, atp synthase complexes,
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