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Report on ribosomes

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Report: Study on Mitochondria and Ribosomes Brief description of the Mitochondria and Ribosomes under study from liver cell. Mitochondria: Mitochondria are usually round and engraved, with a smooth outer membrane and a folded inner membrane. They are approximately 1-10�m in size, and contain upto 1000 cytoplasm in each cell. Mitochondria are the site of aerobic respiration and most of the cells ATP is made here. Ribosomes: Ribosomes are a small dense structure (like a giant enzyme). They are approximately 20nm in size, and are either attached to the endoplasmic reticulum or are found free in cytoplasm. Ribosomes are where the cells genetic code is used to build protein. Obtaining the mitochondria and ribosomes: Differential centrifugation allows us to extract pure samples of a particular organelle. We will be using this method to use obtain the mitochondria and ribosomes from the liver cell. We have decided to use the liver cell as the liver is very active and therefore it would have a plentiful supply of mitochondria, for respiration. ...read more.


6. 7. The mixture is spun at a low speed (800-1000g) for 5-10 minute, the denser parts of the nuclei get spun to the bottom of the test tube, where they form a pellet called the sediment. At this speed, the densest organelle is the nuclei and so this will form a sediment at the bottom of the test tube. 8. 9. The liquid layer on top, called the supernatant, is then poured into a fresh test tube, leaving the nuclei sediment behind. This supernatant is then spun at a faster speed (10000-20000g) for 15-20 minutes, which results in a sediment of mitochondria. The supernatant is poured into a new test tube and the mitochondria sediment is stored for later use. 10. 11. This new supernatant is then spun at 50,000-80,000g for 30-50 minutes to form a rough endoplasmis reticulum sediment. The supernatant is then poured into a new test tube and then spun at an even faster speed (80000 - 100000g) ...read more.


The following table compares the use of electron microscopes and light microscopes: Light Microscopes Electron Microscopes Radiation used Light Rays Electron Beams Magnification �2000 �500,000 Resolving Power 200nm 1nm Focused By Glass Lenses Electromagnet Biological Material Living or Dead Dead Size Small & Portable Very Large and Static Preparation of Material Quick & Simple Time Consuming & Complex Cost Relatively Cheap Very Expensive How does it work? � The source at the top of the microscope emits electrons (-ve charge) � These electrons are attached to the +ve anodeand are then concentrated into a beam by a -ve cathode. � The condensor and objective are electromagnets, which straighten the beam � The projector focuses the image on the screen. Conditions required: � Vacuum - otherwise electrons would hit air molecules. � The sample must be dead - since being placed in a vacuum. We believe that we will see the following images. Colour has been added to make the images more clearer to see. ...read more.

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