Microbiology Lab Exam 1 Questions and Answers Rated A

Microbiology Lab Exam 1 Questions and Answers Rated A when viewing a smear with the oil immersion lens the final magnification is 1000x;10x ocular x 100X objective what is the purpose of heat fixing kill the bacteria, adhere to glass anddenature the proteins of bacteria name oneof the stains or regents used in the gram stain procedure gram crystal violet, gram iodine, gram sfaranin, 95% ethanol why are aseptic techniques used in the lab? to ensure that we do not contaminate what we are working with as as to ensue that we do not acciently inoculate ouselves. example of aseptic techniques are flaming the loop/needle sterilizing it, breifly flaming the test tube before and after obtaining the sample. the gram reaction is due to differences in the structure of wat part of the microbe its cell wall, specifically peptidoglycan, gram positive bacteria have thicker peptidoglycan layer compared to GN bacteria. Name 2 inoculating tools you will be using in this lab loop, needle what color is a gram positive microbe purple waht is the function of the ethanol in the gram stain procedure decolorize name one of the strains in the acid fast stain cold kinyoun, carbol fuschsin, methylen blue name one of the stains in the endospore stain malachite green, safranin what is the purpose of the acid-fast stain the purpose of the acid-fast stain is to differentiate between the myobactriace family of bacteria from all other bacteria what color does na acid-fast microbe stain with acd-fast stain red what is the function of agarin the media agar allows media to remain solid at room temperature what is the difference between broth and agar based media broth is liquid media at room temperature, agar media is solid at room temp. what is the funciton of media media is used to provide nutrients to a microbe as well as a growth medium what is the name of the plate inoculation technique quadrant steak plate Why must the media we are making today be sterilized prior to us? the meda must be sterilized to remove any bacterial contaminant that may be introduced when the media is made how do you know yo have dont a successful streak plate? youve ended up with isolated colonies what do you think will happen if you inoculated an obligate anerobe onto a TSA plate and incubated the incubator we have been using? the obligate anerobe would not grow because it doesn't have the ability to produce th necessary enzymes to dtoxify toxic oxygen species What is one procedure used to determine oxygen requirement of a micrboe thioglycollate medium or anaerobic bag why are we working at differnt temperature in the growth curve excersize? to demonstrate th differences in bacterial growth rate at different temperatures why are we using the spectrophotometer in todarys class to determine the optical density of our sample. this number will correlate the amount of bacteria in the sample all microbes require oxygen true or false false name four stages o growth in a closed system growth curve lag phase, log phase, stationary phase, death phase we will be using our data to calculate the generation time of the vibrio. when calculating generation time one must use information fro which of the growth phases the log phase will a faculative anerobe grow on both presence and absence of oxygen yes Name hte media used in chapter 4 mannitl salt agar, eosin mthylene blue agr, macconkey agar, ef media define selctive ingredient slective ingrediant inhibit some bacteria what is the funciton of a different ingredient in a media diffferent ingredients differentiate different bactera based on a coloe/appearence due to a biochemical reaction the bacteria carries out when might it be helpful to use a selective media it may be helpful to us a selective media when trying to determine between two different population of bacteria one of the selective media you are using today detects lactose fermentation. if a microbe was shown to be a lactose fermenter on the media would it be necessary to do an OF test on this microbe. why or why not it is not necessary to do an OF test. The OF tests for glucose oxidation/fermentation and lactose is made up in part of glucose. therefore we already know the microbe can ferment both lactose and glucose name one of thest we are doing that will determine glucose fermentation. Ineach of these test glucose is fermentation is indicated by? kligler's iron agar: yellow broth Glucose fermentation tubes: yellow broth OF test: yellow color change The OF test determines what about a microbe it determines whether or not a microbe can metabolixe carbohydrates either oxidatvely, germentatively, both or not at all(nonsaccharolytic) What is one characteristics of a microbe that can be determine by using SIM media? SIM media determins whether a microbe can reduce sulfure/produce H2S, breakd ont tryptophan into indole and pyruvate and or is motile or not. If a microbe has the ability to hydrolyze starch it can break down starch to glucose microbes that can hydrolyze gelatin break gelatin down into gelatin-->polypeptides--> aminoacids The MRVP test is only done on fermentive microbes (T/F) true KIA cotnains phenol red. what is the role of phenol red in this media? phenol red serves as the pH indicator What is one of the characteristics of a micrboe that can be determined by using KIA? whether it can ferment glucose or lactose, produce H2S//reduce sulfur and or produce gas A positive catalase test is indicated by oxygen bubbles name on of te test dont using a KIA slant glucose fermentation, lactose fermentation, sulfur reduction/H2S production, and or gas production name one of the test done using media SIM sulfur reduction/H2S production, presence of indole, and motility If a microbe is fermentative in a glucose fermentation tube, what result would you expect to get when the same micrboe is tsted in an OF test? both tubes in an OF test would be yellow, which could indicate two things: it canbe with fermentative both )-F or it could indicate glucose fermentation if a microbe gives a fermentative result ina lactose fermentation tube what result would you expect ina glucose fermentation tue? can you predict this result without does the test? ANS: Both tubes in an OF test would be yellow, which could indicate two things: it can be either fermentative (F) or both oxidative-fermentative (O-F), which would indicate glucose fermentation and lactose fermentation. If a microbe can metabolize lactose or even sucrose, it must be able to ferment glucose. Lactose and sucrose, which are polysaccharides, are made up of glucose, a monosaccharide. So yes, you can predict this result without doing the glucose fermentation tube test. The citrate slants tests for the microbes ability to use citrate as its sole carbon source due to the presence of citrate on this informaiton what does a postivie citrate slant look like? a positive citrate test is indicated by wither a color change of the media from green--> blue or no color change at all, but growth must be apparent. in both these instances citrate is utilized UV light is lethal to bacteria because it has an effect on the _____of the bacteria DNA what are we convering one of two plates with foil in today's lab? after eposure to UV light for 15 seconds Do you think there will be a difference in the effect of UV light on the 24 hr vs the 7 dy old culture of B. subtilus?why? yes, the 7 day culture has developed endospores in response to depeting nutrients in the plates. endospores are resistent to UV light. 24 hour culture does not have endospores. what is the variable in the second hald of today's alb? leaving the plate unfoile vs. foiled to witness DNA repair using photoractivation vs. dark repair pathways Name one biochemcial test we will be doing in lab KIA,OF, GLucose/lactose/sucrose,SIM, urea hydrolysis, phenylananine demanisase test, SIM pseudosell what is meant by a differential test a diagnostic system used for the purpose of differentiating and sometimes idetngying a microbe from anothe mcrobe what is the reson biochemical tests are dont on micrboes in order to differentaite microbes more accurately fro each other based on their specific biochemcial characterisitcs in many of the test we are doing we are looking for microbes ability to prodcue a specific_____by giving the mcirboe a specific subtrate and looking for a specific product enzyme