BMSC 210 Midterm 1 Study Guide | 100% Correct Answers | Verified | Latest 2024 Version What are properties of all cells? - ✔✔ Growth Metabolism Evolution LUCA - ✔✔Last universal common ancestor How do we decide how the phylogenetic tree is drawn? - ✔✔Use ribosomes. All organisms have it and it has been the same for billions of years What are the domains? - ✔✔ Bacteria Archaea Eukarya What defines the domains of cells? - ✔✔Their rRNA sequencing What domains are most closely related? - ✔✔Archaea and eukarya What emerged from Archaea? - ✔✔Eukarya How do we know kw when oxygen appeared in our biosphere? - ✔✔Reduced iron deposits coating the bottom of ancient oceans Who invented microscopes? - ✔✔Robert hooke What are Robert Koch's postulates on infectious disease? - ✔✔1. The microorganism or other pathogen must be present in all cases of the disease 2. The pathogen can be isolated from the disease Nederland host and grow in a pure culture 3. The pathogen from the pure culture must cause the disease when inoculated into a healthy, susceptible lab animal 4. The pathogen must be resonated from the new host and shown to be the same as the originally inoculated pathogen Why is staining important in microscopy? - ✔✔Increases contrast Resolution - ✔✔The ability to distinguish two adjacent objects as separate and distinct How is resolution determined? - ✔✔Determined by the wavelength of light used and numerical aperture of lens. Shorter wavelength= better resolution. Higher numerical aperture = better resolution What is the limit of resolution for a light microscope? - ✔✔0.2 um What happens when we reach the limit of resolution? - ✔✔Further magnification doesn't provide any additional detail Light microscopy - ✔✔Uses visible light to illuminate cells Types of light microscopy - ✔✔Bright field Phase contrast Dark field Flourescence Bright field microscopy - ✔✔Specimens visible because of differences in contrast (density) between specimen and surroundings. Total magnification = objective lens magnification x ocular lens magnification Max mag is 2000x Why is oil used in microscopy? - ✔✔Stops refraction Phase contrast microscopy - ✔✔Phase ring amplifies differences in refractive index of cell and surroundings. Doesn't need stain, allows live samples Image is dark cells on light background. Kind of looks like light field but more 3D and has glow around it Dark field microscopy - ✔✔Light reaches specimen from sides and is scattered by specimen. Image appears light on dark background. Good for observing motility Flourescence microscopy - ✔✔Used in microbial ecology for enumerating bacteria Uses stains which target DNA Differential interference contrast (DIC) microscopy - ✔✔Uses 2 beams of light to visualize 3D images of endospores, vacuoles and granules that wouldn't be visible using bright field Atomic force microscopy (AFM) - ✔✔A tiny stylus is placed close to the specimen and measures weak repulsive forces between it and specimen. Computer generates an image based on this
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