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Beneficial Activities

Beneficial Activities - Beneficial Activities Food...

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Beneficial Activities Food production Fermentation of milk Bioremediation Use organisms to degrade environmental waste Genetic engineering Introduce genes of one organism into an unrelated organism to confer new properties on the organism To produce medically important products and vaccines Engineered plants resist disease Potentially therapeutic – gene therapy Ch. 2 Microscop e Lenses and bending of light - Light is refracted (bent) when passing from one medium to another – from lens to air , organism, - Refractive index – a measure of how greatly a substance slows the velocity of light - going to be looking at glass and air or glass and oil Lenses - Focal point – focus light at a specific place - 25 cm or 10 in – what our eyes can focus on Many types (2 or more lenses, compound microscopes) Bright field – dark image against brighter background Several objective lenses – parfocal microscopes remain in focus when objectives are changed. In focus as you rotate around Total magnification - Dark field - image is formed by light reflected or refracted by specimen - produces a bright image of the object against a dark background - used to observe living, unstained preparation Eukaryotes – internal structure Prokaryotes – identify bacteria -Used as dark field stop---
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Phase-contrast – enhances the contrast between intracellular structures having slight differences in refractive index. Excellent way of observing living cells. Based on the wave nature of light rays and the fact that light rays can be in phase. Fluorescence – exposes specimen to lasers of a particular frequency of light, ultraviolet, violet, or blue light. Ability of substances to absorb short wavelengths of light (uv) and give off light at a longer wavelength - Flurochromes – usually specimen are stained with this - Tagged antibodies - Shows a bright image of the object resulting from the fluorescent light emitted by specimen - Apps in microbiology and microbial ecology studies - antibodies are natural defense molecules that are produced by humans and man animals in reaction to a foreign substance or antigen. Magnification - microscope has 2 magnifying lenses, called compound microscope, lens include (ocular lens and objective lens) Microscope resolution - Ability of lens to separate or distinguish small objects that are close together - Resolution – shorter wave length, greater the resolution Immersion oil – refractive index of air is 1.0 Light passing through air cannot have a higher index than 1.0 - Glass and immersion oil have the same refractive index of 1.5 Differential interference contrast microscope DIC - creates an image by detecting differences in refractive indices and thickness of different parts of specimen. - Excellent way of observing living cells. Live appear brightly colored Principles of light microscopy - Confocal scanning laser microscope - used to construct 3d image of thicker structures - specimens are stained with flurochrome so they will emit light.
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