The electron microscope‚ instrument that produced the first magnified image showing three-dimensional’ and highly magnified image of a small object. It directs a beam of electrons rather than light through a specimen. The beam of electrons is created from an electron gun. This beam then travels through the length of the microscope cylinder‚ which contains the lenses‚ the specimen chamber‚ and the image-recording system. Two types of electron lenses are used‚ electrostatic and electromagnetic
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The Discovery Of The Electron The electron was discovered in 1895 by J.J. Thomson in the form of cathode rays‚ and was the first elementary particle to be identified. The electron is the lightest known particle which possesses an electric charge. Its rest mass is Me <approximately equal> 9.1 x 10 -28 g‚ about 1/1836 of the mass of the proton or neutron. The charge of the electron is -e = -4.8 x 10^-10 esu <elec trostatic unit). The sign of the electron’s charge is negative by convention‚ and
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structure and function of the nucleus and mitochondria. The mitochondria is a semi-autonomous organelle which reproduces by bynary fission and has its own DNA. Its main function is to produce the energy intermediate ATP‚ through ATP synthase. Mitochondria could be considered a cell inside a cell. It has its own membranes (inner and outer membranes)‚ its ribosomes (to produce the proteins encoded in its DNA)‚ a matrix -- where aerobic respiration occurs. The invaginations of the inner membrane‚ called
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Altering an egg cell in order to create a healthy baby is a very controversial issue. Physically separating an unhealthy egg and transferring the DNA to a healthy donor seems like a positive thought. On one hand‚ it seems very helpful for an unhealthy mother‚ but there may be many underlying problems. The ethical issues‚ along with possible legal ramifications‚ evolutionary impacts and regulation pose possible concerns. For example‚ who should have the authority to make such a decision in the first
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Citric acid cycle From Wikipedia‚ the free encyclopedia Jump to: navigation‚ search [pic] [pic] Overview of the citric acid cycle The citric acid cycle — also known as the tricarboxylic acid cycle (TCA cycle)‚ the Krebs cycle‚ or the Szent-Györgyi-Krebs cycle‚ [1][2] — is a series of enzyme-catalysed chemical reactions‚ which is of central importance in all living cells that use oxygen as part of cellular respiration. In eukaryotic cells‚ the citric acid cycle occurs in the matrix of the mitochondrion
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solitude after returning home from the war. Harold Krebs‚ a World War I veteran‚ attended school at a Methodist college in Kansas but enlisted in the Marines in 1917. Krebs now lives at home with his father‚ mother and two sisters where he spends his days reading books or playing pool. Krebs is careful to keep his life simple due to the fact that he isn’t fond of change. Is Harold Krebs apprehensive to making a change in his daily lifestyle? When Harold Krebs returns home late‚ his return is not celebrated
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A cycle is defined as any complete round or series of occurrences that repeats or is repeated in the same order and at the same intervals. The natural existence of cycles is highly important without cycles resources would run out and organisms would die. The amount of carbon nitrogen and oxygen on the earth is fixed‚ they can exists in different forms but no more may be added. So that these don’t run out they are cycles so they may be reused. Photosynthesis and respiration are the reverse of each
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Courage’’ and Ernest Hemingway’s ‘’Soldier’s Home’’ are about two soldiers who comes home from war uncelebrated. Harold Krebs and Paul Berlin have many similarities and differences. They are both soldiers and each have been fighting a war‚ Berlin the Vietnam war‚ Krebs World War 1. Both of the characters get antisocial and depressed by the war. The reader gets to know that Krebs is depressed and antisocial by him only giving short answers‚ which are mostly yes or no. Berlin‚ on the other hand‚ just
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Care labelling Care labels are care instructions on garments. Symbols are written on care labels‚ attached to clothing to indicate how a particular item should best be cleaned. Textile and apparel labels can help you consider alternative choices and make better buying decisions if you take time to read them. Permanent Care Labels (PCL) use symbols to explain how to care for wearing apparel and home sewing fabrics‚ so consumers need to learn the basic symbols. Introduction | | Caring for
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The Endosymbiont Hypothesis and the evolution of the Chloroplast and Mitochondria Dr Lynn Margulis is seen as the first person to have put forward the Endosymbiont Hypothesis which is based on a theory which explains the likely origin of the mitochondria and chloroplast (plants) in eukaryote organisms which we observe today. Dr Margulis received evidence from all over the world and from many scientific researchers and experiments‚ Margulis simply had to put all the evidence together to form her
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