MIBO 3500 EXAM 1 WITH 100% CORRECT ANSWERS

microbe living single-celled organism that requires a microscope and has the capacity to reproduce some microbes can be seen without a microscope naming system used:________; 1st word: _________________; always ____________; 2nd word: _______________; full name is always: ____________ binomial; genus -- capitalized; specific epithet; italicized or underlined Who built the compound microscope and coined the term "cell"? Robert Hooke Who first observed single-celled microbes? Antonie van Leeuwenhoek spontaneous generation living creatures could arise without parents *rejected by many scientists Who demonstrated that microbes cause fermentation and food spoilage and is known as the father of MIBO? Louis Pasteur importance of swan-neck flasks determined that diseases have identifiable causes Who configured the 3 domains? (eukarya, archaea, and bacteria) Carl Woese Magnification of light microscope 1000x what happens in a light microscope? (bright-field microscope) light passes thru specimen -- then thru a series of magnifying lenses magnification of electron microscope 100,000x magnification of scanning probe microscope view at atomic level wavelength of visible light 400 - 750 nm absorption photon's energy is acquired by the absorbing object reflection a wavefront bounces off the surface of an object refraction bending of light as it enters a substance that slows its speed scattering a wavefront interacts with objects smaller than the wavelength of light the 3 elements of light microscopy magnification, resolution, contrast magnification the ratio of the size of an object to the size of its image -- image is seen as larger than object -refracts light to spread its waves (bends the light precisely) components of a compound microscope 2 magnifying lenses: ocular lens (10x) and objective lens (greater than 100x) total magnification is product of ocular and objective lenses resolution ability to resolve two objects very close together; quantified as the minimum distance between two objects where they still appear separate what does resolution depend on? quality of lens and wavelength of light empty magnification magnification without increasing detail -- results in highly pixellated image what is the detail of an image limited by? the wave nature of light -- light rays undergo interference higher quality lens = better resolution = ____________ higher Numerical Aperture name a method that increases resolution immersion oil method - decreases bending of light since n(oil) is approximately equal to n(glass) contrast -number of visible shades in a specimen -(difference in light intensity between the image and the adjacent background relative to the overall background intensity) how do you achieve a higher contrast? stains stains dyes that carry a charge and bind cells are basic or acidic dyes more commonly used? basic - (+) charge -examples: methylene blue, safranine, crystal violet types of stains simple differential special simple stain -determine the size, shape and arrangement of prokaryotic cells; -increases contrast between cell and background -all cells stain the same color differential stain; types distinguish organisms based on staining properties; gram and acid-fast gram stain type of differential stain that separates bacteria into 2 major groups based on differences in their cell walls color of gram positive stain purple (thick PG layer) color of gram negative stain pink (thin PG layer) gram stain process primary stain - crystal violet; mordant - iodine traps primary dye in cell; decolorizer (usually alcohol) - removes primary dye from gram (-) cell counter/secondary stain - safranin recolors cells that lose stain thru decolorization acid-fast stain -distinguishes the genus Mycobacterium -high lipid content in cell wall prevents uptake of dye -uses heat to facilitate staining -stains bacteria red types of special stains capsule stain - example of negative stain; endospore stain - enhances endospore; flagella stain - increases diameter of flagella name the different kinds of light microscopy bright-field, phase contrast, dark-field, fluorescence phase contrast microscopy -amplifies differences in refractive index of cells and the surrounding medium -set of rings and diaphragms in condenser achieve better resolution dark-field microscopy specimen appears bright agains dark background fluorescence microscopy used to observe organisms that are naturally fluorescent or tagged with fluorescent dye -fluorescent molecules absorb UV light and emits visible light -image fluoresces on dark background what happens at excitation wavelength? (of fluorescence microscopy) fluor absorbs light of a specific wavelength what happens at emission wavelength? (of fluor. microscopy) fluor emits light at a longer wavelength why are filters used in fluorescence microscopy? -excitation filter: passes only the wavelengths absorbed by the fluorophore -- minimizes excitation of other sources of fluorescence -emission filter: passes only the wavelengths emitted by the fluorophore and blocks all undesired light outside this band - especially the excitation light -optical filters ensure the darkest background. fluorophore fluorescent chemical cmpd that makes it possible to focus on specific parts of a cell; how is specificity of a cell determined? chemical affinity, labeled antibodies, DNA hybridization, protein fusion electron microscopy uses electromagnetic lenses, electrons, and a fluorescent screen to produce images; resolution is 1000x greater than L.M. -- electron has smaller wavelength than light; magnification is 100x greater than L.M.