BIOS-242 Week 1 Discussion: Microscopy | Best for revision.

Micro BIO: Week 2 Discussion 1: 1.) Q.) What microscope would you use to study the complex interactions of microorganisms in a biofilm? Why is this the best choice? What w ould be your second choice? Consider applying confocal, fluorescent along with electron or light microscopes to your post. A.) I would definitely use electron microscope to study the complex interactions of microorganisms in a bio-film because of its excellent resolution properties. The electron microscope is the most important tool for the bio-film scientist. Electron microscope has been used for the test and study of bio-films on medical devices and in human infections. My second choice would be a compound light microscope which contains four objective lenses. The resolution might be lower but it is inexpensive, easily available and doesn't require electricity for it to magnify. The use of transmission electron microscopy and specific polysaccharide stains like ruthenium red allowed researchers both to identify the nature of these extracellular fibers in bio-films and to better elucidate their association with the cells. 2.) Q.) 2). A microbiologist wants to determine what different types of bacteria are found in a mixed bacterial culture. When he puts a sample of the culture under a bright field microscope, he cannot see anything. What are some ways he can increase resolution and contrast so he can see the bacteria better? What are different shapes of bacteria that he may see? A.) Light rays can be manipulated to increase the resolution and contrast of a specimen in a variety of ways. In bright-field microscopes, immersion oil is used to capture light rays that would otherwise be refracted and lost; the result is an increase in the resolution of the image. Dark-field microscopes purposely scatter light rays in such a way as to improve the contrast of the specimen. Phase-contrast microscopes alter the wavelengths of light rays by making them in and out of phase with each other, thereby increasing contrast. Finally, fluorescent microscopes use UV light, which produces 3.) . Q.) increased resolution because of its shorter wavelength, and the fluorescent dyes that are used emit a variety of colors, increasing contrast. Who can explain why electron microscopes magnify only dead organisms? A.). The specimen must be held in a vacuum chamber, with no air & liquid. Electrons are particles and there are also particles which comprise air. Without a vacuum, the electrons would strike and be scattered by the atoms/particles of the air components. Exposure to a vacuum is the method for fixing the specimen to the slide grid for an electron microscope. Without vacuum exposure, the specimen would slide off and would not be visible. Electrons are highly radioactive, and the chamber must be completely sealed to prevent them from escaping and contaminating the lab area. Electrons are particles and there are also particles which comprise air. Without a vacuum, the electrons would strike and be scattered by the atoms/particles of the air components. Show Less