Gianna Melendez
Chamberlain College of Nursing
Support the Endosymbiotic Theory The endosymbiotic theory proposes that eukaryotes formed from the union of small aerobic prokaryotes with larger anaerobic prokaryotes, which form organelles. The smaller prokaryotes were not destroyed by the larger cells, but instead became internal parasites that remained surrounded by a vesicular membrane of the host. The theory proposed that mitochondria are the result of endocytosis of aerobic bacteria and chloroplasts are the result of endocytosis of photosynthetic bacteria. The theory states that parasites will eventually lose their ability to exist independently, but they will still be able to retain …show more content…
In plant cells, the cell wall is located around the cell membrane. In bacteria, the cell wall is located on the outside of the cell. Just like prokaryotic cells, the mitochondria have their own cell membranes. The outer membrane of the mitochondria is synthesized by which the original host cell engulfing the endosymbiotic bacteria, which created the mitochondria. The outer membrane has structural and chemical similarities to the eukaryote cell membrane. The sequencing of proteins and nucleic acids proved that there is a genetic link between these organelles and their ancestral cells. Therefore, mitochondria arise from preexisting mitochondria and chloroplasts arise from preexisting chloroplast. They are not crated through the direction of nuclear genes. All eukaryotes have some sort of mitochondria, while only photosynthetic eukaryotes have chloroplasts; it has been proposed that endosymbiosis occurred twice. First, a larger host cell took in an aerobic heterotrophic prokaryote. The prokaryote co-evolved with the host, eventually becoming something like a mitochondrion. Next, a mitochondrion-containing cell took in a photosynthetic prokaryote. This model of eukaryote origins is called serial …show more content…
Cells rely on ribosomes when they need to produce more protein. They are found in all living cells and they host protein synthesis. They can occur as free particles in prokaryotic and eukaryotic cells and also attaches to the membranes of endoplasmic reticulum in eukaryotic cells. When it comes to size, ribosomes are roughly spherical and usually measure 200 angstroms in diameter. To get an idea of how small this is, imagine trying to pick one little speck of dirt in your yard. There is no way you could do or see the speck unless you use a microscope. Occasionally, when you look into the microscope the ribosomes will be clustered together. This is called polysomes because the ribosomes are being held together by messenger