Portage Microbiology Exam 3 Flashcards _ Quizlet

11/28/23, 4:33 PM Portage Microbiology Exam 3 Flashcards | Quizlet https://quizlet.com/751449486/portage-microbiology-exam-3-flash-cards/ 1/3 Unable to process payment Please update your payment information to continue to access your Quizlet Plus benefits, including custom creation tools and ad-free studying. Dismiss Update Now Portage Microbiology Exam 3 8 studiers today Leave the first rating Students also viewed Terms in this set (37) Portage Microbiology Exam #3 26 terms maggier1215 Preview Portage Microbiology Exam #4 26 terms Sajjid_Ahamed Preview Microbiology Lab Techniques 5 terms Tomsic_707_ Preview P Lecture 20 26 terms TiffanieA micrometer one millionth of a meter, 10^ -6 nanometer one billionth of a meter, 10^-9 Resolution the distance between two objects at which the objects still can be seen as separate What happens if the resolution is poor? Poor or low resolution means two (or more) objects may appear as one. Contrast the difference in light absorbance between two objects. What happens if there is poor contrast? gives a high background and makes the visualization of multiple objects difficult. If you wish to increase the amount of light going into a microscope, what part would you adjust? The iris diaphragm As light passes through a microscope, what is the last piece that light passes before reaching your eyes? the ocular lens, or eyepiece, directly into your eye. How is the total magnification of an object calculated? Total magnification is calculated by multiplying the power of the objective and the power of the eyepiece. What is one limitation of fixing your sample? Fixation requires you to irreversibly kill your sample. Thus, determining the motility (cell movement) of a sample is impossible. Fixation also runs the risk of distorting the specimen shape and arrangement. Portage Microbiology Exam 3

11/28/23, 4:33 PM Portage Microbiology Exam 3 Flashcards | Quizlet https://quizlet.com/751449486/portage-microbiology-exam-3-flash-cards/ 2/3 Phase-contrast microscopy provided what benefits to imaging? Phase-contrast microscope can provide detailed images of live cells without staining. Able to visualize certain structures that would otherwise be invisible What is the distinguishing feature of dark field microscopy? dark field microscopy reflects light off of the specimen at an angle. The resulting image is an exceptionally dark background and a vibrant specimen. Unlike brightfield microscope, fluorescence microscopes illuminate samples through what spectrum? Fluorescence microscopes illuminate samples through the UV Spectrum. What is the primary difference between TEM and SEM? During transmission electron microscopy the electron passes through the sample whereas during scanning electron microscopy the electron is reflected off the sample creating a three dimensional 'shell' model of the specimen. Gram staining is based on what basic principle? Gram staining, developed by Hans Christian Gram in 1884, began with the basic observation that different types of bacteria react differently to various dyes. Some bacteria readily take up a specific dye while others do not. What is a key determinant in a bacteria being Gram- positive? Gram-positive bacteria have a thick peptidoglycan layer. The Gram stain exploits this characteristic by using the dye combinations of Crystal violet and Iodine. Crystal violet is retained by the thick peptidoglycan cell wall and forms a stable complex with iodine (upon its addition) effectively trapping the dyes in the cell. The resulting mixture is a purple coloration of the cell. What is the purpose of heat fixing a sample? Heat fixing ensures the samples tightly adhere to the glass slide prior to staining (and washing) procedures. What is the primary purpose of a wet mount? Wet mounts are most often performed to visualize live cells as well as the motility and behavior of an organism. The acid-fast stain is most often used to identify what specific microorganism? Acid-fast stains are used to identify bacterial stains showing a high degree of resistance to decolorization. Mycobacterium tuberculosis is the most common use for an acid-fast stain. the closer two objects are to each other the __________________ the resolution requirement greater before the light reaches the sample, it first passes through a ________________ converging the light beams into a focused area on the sample condenser the degree of magnification is ______________________ to the amount of light needed/to image samples clearly at higher magnifications, more light is required directly proportional What stain stains blood cells? Wrights stain Giemsa stain combined with Wright's stain, the resulting combinatorial stain can be applied to blood smears to determine the presence (or absence) of pathogenic bacteria — human (blood) cells appear purple and bacterial cells appear as pink Portage Microbiology Exam 3