دانلود کتاب درک میکروبها(pdf)
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However virus structures, and sizes, are quite diverse. Many, including some important human pathogens, are much larger than MS2 and have complex structures including, in some cases, a lipid coat. But virtually all viruses are so small that the human eye cannot see them, even with the aid of a light microscope –an electron microscope is needed to ‘see’ them. There are, however, some that are larger. The largest known viruses, such as the mimivirus which infects protozoa, are similar in size to some of the smallest bacteria, and they have a genome size to match. But even the largest and most complex viruses are completely unable to replicate without infecting a suitable host cell. At several points within this book we will consider viruses that infect bacterial cells. These are called bacteriophages, or just phages for short (the word ‘phage’ being derived from the Greek ‘phagein’, meaning ‘to eat’). These are very widespread in nature and they can be of real practical significance – a phage infecting a bacterium that is used, for example, in the production of yoghurt can cause serious economic losses. But they have also played a major role in scientific research. Much of our knowledge of how genes work comes originally from studies of phages, where the simplicity of their structure, and the ease with which they can be grown and manipulated, made them invaluable models....
دانلود کتاب درک میکروبها(pdf)