BIOL 306 QUIZ 2 QUESTIONS AND ANSWERS

equation for microscope calibration OD = SD x 10um stage micrometer ruler w lines 10 um apart define simple stain uses only one dye - used bc pos and cell walls are neg common simple stains - methylene blue - crystal violet - safranin heat fixing prevents microbe from being washed off cocci circle bacilli rod shaped spiralla spiral shaped basic dye pos charged pure culture only contains one species streak plate method inoculating loop used to drag the culture back and forth across the agar to separate the individual colonies of a culture selective media inhibit growth of unwanted organisms and provide environment for selected organism to grow differential media permit visual distinction between different types of media hemolytic bacteria - beta: complete breakdown - alpha: partial breakdown - gamma: no breakdown - use blood agar plate gram neg control e. coli gram pos control m. luteus EMB agar - inhibit gram pos growth - eosin and methylene blue - lactose that bacteria consume and turns metallic green - weak fermentation = pink/purple MacConkey agar - selective for gram neg (ONLY GRAM NEG) - lactose, bile salts, neutral red, and crystal violet - fermenters turn neutral red to red/pink Mannitol salt agar - selects for salt tolerant bacteria - turns yellow if acidic gram pos cell wall thick layer of peptidoglycan gram neg cell wall consist of lipopolysaccharide outer membrane and thin peptidoglycan - ethanol washes away LPS and is why it doesn't stain purple crystal violet dye causes gram neg and pos cell to turn purple - only stays on gram pos - complexes w iodine ethanol washes away purple of gram neg (LPS) and leaves it clear safranin turns clear gram neg pink