Microbiology WJC Chpt 3 2013 – Flashcards
Unlock all answers in this set
Unlock answersquestion
| Explain what the five I's mean and what each step entails? |
answer
| -Inculation -Incubation -Isolation -Inpection -Identification |
question
| The term "culture" refers to the _____growth of microorganisms in ____. a. rapid, an incubator b. macroscopic, media c. microscopic, media d. artifical, colonies |
answer
| b. macroscopic, media The term "culture" refers to the macroscopic growth of microorganisms in media. |
question
| A mixed culture is____. a. the same as a contaminated culture. b. one that has been advequately stirred. c. one that contains two or more known species. d. a pond sample containing algae and protozoa |
answer
| A mixed culture is____. c. one that contains two or more known species. |
question
| Resolution is ____with a longer wavelength of light. a. improved b.worsened c. condenser d. eye |
answer
| Resolution is ____with a longer wavelength of light. b.worsened |
question
| A real image is produced by the a. ocular b. objective c. condenser d. eye |
answer
| A real image is produced by the objective |
question
| A microscope that has a total magnification of 1,500X when using the oil immersion objective has an ocular of what powera. 150X b. 1.5X c. 15X d. 30X |
answer
| c. 15 X Know how to do the formula!!!! |
question
| The specimen for an electron microscpe is always : a. strained with dyes b. sliced into thin sections c. killed d. viewed directly |
answer
| c. killed |
question
| Bacteria tend to stain more readily with cationic (positively) charged dyes because bacteria a. contain large amounts of alkaline substances b. contains a large amount of acidic sunstances c. are neutral d. have thick cell walls |
answer
| Bacteria tend to stain more readily with cationic (positively) charged dyes because bacteria b. contains a large amount of acidic sunstances |
question
| Describe Inculation |
answer
| A sample is placed into a container of sterile MEDIUM containing appropriate nutrients to substain growth. Inculation involvesspreading the sampleon the surfaceof a solid medium or introducting the sample into a flask or tube. Selection of medium with specialized functions can improve later steps of isolation and identification. SOme microbes may require a live organism (animal or egg) as a growth medium. |
question
| Incubation |
answer
| a incubator creates the proper growth temperature and other conditions. This promotes multiplication of the microbes over a period of hours, days and even weeks. Incubation produces a culture the visible growth of the microbe in or on the medium. |
question
| What term is used to describe a pile of microbes that is visible to the naked eyea. plaque b. hive c. colony d. Thallus |
answer
| term is used to describe a pile of microbes that is visible to the naked eyec. colony |
question
| What is media contained in? |
answer
| test tubes flasks petri dishes |
question
| how many different types of media? |
answer
| At least 500 different |
question
| List the three classifications of Media Classification |
answer
| Physical state chemical composition functional type |
question
| List the physical state of media classification |
answer
| 1. liquid 2. semisolid 3. solid (can be covereted to liquid) 4. solid (cannot be liquidified) |
question
| Chemical composition media list two types? |
answer
| 1. Synthetic (chemically defined) 2. Nonsynthetic (complex, not chemically defined) |
question
| List 8 functional types of media |
answer
| 1. general purpose 2. enriched 3. selective 4. differential 5. anaerobic growth 6. specimen transport 7. assay 8. enumeration |
question
| List the 3 physical states of media? |
answer
| 1. liquid media 2. semisolid media 3. solid media |
question
| Describe liquid mediagive examplesHow do you know their is growth? |
answer
| Liquid media is water-based solutions, do not solidify at temperature above freezing Examples: broth, milk or infusions -growth is seen as cloudiness or particulates |
question
| Describe semi-solid media: --used to what? |
answer
| clot -like consistency at room temperature used to determine motility and to localize reactions at specific site |
question
| Describe solid media- why is it useful? |
answer
| Solid media is a firm surface on which cells can form discrete colonies. Liquefiable and nonliquiuefiable Useful for isolating and culturing bacteria and fungi |
question
| Chemical content of defined or synthetic media? |
answer
| defined or synthetic media-compositions are precisely chemically defined |
question
| Chemical content of media that is complex or nonsynthetic media? |
answer
| complex or nonsynthetic media -if even just one component is not chemically definable |
question
| Describe general purpose media- (function) Examples |
answer
| general purpose media- to grow as broad a spectrum of microbes as possible. -usually non-synthetic -contain a mixture of nutrients to support a varient of microbes Example: nutrient agar and broth, brain-heart infusion, tryptic soy agar (TSA) |
question
| a fatidious organism must be grown on what type of medium? |
answer
| synthetic medium and enriched medium |
question
| True or false A subculture is a culture made from a isolated colony |
answer
| True |
question
| True or false: Agar has the disadvantage of being easily decomposed by microorganisms. |
answer
| False Agar IS NOT easily decomposed by microorganisms (gelatin can be) |
question
| True or False The factor that most limits the clarity of an image in a microscope is the magnification |
answer
| FALSE The factor that most limits the clarity of an image in a microscope is the RESOLUTION |
question
| True or False Living speimens can be examined either by light microscopy or electron microscopy |
answer
| FALSE: Living specimens can be examined with phase -contrast or differential interference microscopy |
question
| True or False The factor that most limits the clarity of an image in a microscope is the magnification |
answer
| FALSE The factor that most limits the clarity of an image in a microscope is the RESOLUTION |
question
| True or False Living speimens can be examined either by light microscopy or electron microscopy |
answer
| FALSE: Living specimens can be examined with phase -contrast or differential interference microscopy |
question
| True or False The best strain to use to visualize a microorganism with a large capsule is a simple strain |
answer
| False: The best strain to use to visualize a microorganism with a large capsule is a NEGATIVE strain |
question
| Describe Enriched media Give Examples |
answer
| Contains complex organic substances (growth factors-vitamins, amino acids)to support growth of fastidious bacteria Example: blood agar, Thayer-Martin medium (chocolate agar) |
question
| Describe Selective media give examples |
answer
| Allow only certain things to grow. contains one or more agents that inhibit the growth of certain microbes but not others. Example: mannitol salt agar (MSA) MacConkey agar, Hektoen enteric (HE) agar |
question
| Differential media- Describe and give example |
answer
| Differential media-allow multiple types of microorganisms to grow but display visible differences among those microorganisms. MacConkey agar can be used as a differential medium as well. |
question
| Describe reducing media and what it is used for? |
answer
| reducing media- absorbs oxygen or slows its penetration in the medium; used for growing anaerobes or for determing oxygen requirements |
question
| Carbohydrate fermentation media- describe--what is it used for? |
answer
| carbohydrate fermentation media-contain sugars that can be fermented and a pH indicator; useful for identification of microorganisms |
question
| Describe assay media- used to test? |
answer
| assay media-used to test the effectiveness of antibiotics, disinfectants, antiseptics |
question
| When X-Gal is present in a media, lactose fermenting colonies turn blue while those that cannot ferment lactose remain white. What kind of media is nutrient agar when X-Gal is added? a. selective B. Differential C. Enriched D. General purpose |
answer
| B. Differential |
question
| Why do we use immersion oil with our 100X objective lensesa. reduce light scatter b. reduce ilumination c. reduce maginification d. Reduce contrast |
answer
| a. reduce light scatter |
question
| Describe Bright-Field microscopy? |
answer
| -Most most widely used. -Forms its image when ligh is transmitted through the specimen -The specimen produces an image that is darker than the surrounding iluminated field. Can be used with live, unstained and preserved, stain specimens |
question
| Describe Flurorescence microscopy? |
answer
| -includes a UV radiation source and a filter that protects the viewer's eyes -used the dyes that show fluorescennnnnnce under UV rays Forms a colored image against a black field -used in diagnosing infections caused by specific bacteria, protozoans, and viruses using fluorescent antibodies |
question
| electron microscopy |
answer
| -Focused electon beam -Wavelength=6pm -1000,000 X less than red visible light offers better resolution -samples are dead |
question
| What wavelength of light would give the best resolution when viewed directly with your eyes? a. red (650 nm) b. Yellow (570nm) c. Violet (400nm) d. ultraviolet (260 nm) |
answer
| c. Violet |
question
| What are the 2 living preparations in Lab? |
answer
| wet mount hanging drop mount |
question
| Describe a wet mount? |
answer
| Cells are suspended in fluid, a drop or two of the culture is then placed on a slide and overlaid with a cover glass -cover glass can damage larger cells and might dry or contaminate the observer's fingers. |
question
| Desccribe hanging drop mount? |
answer
| Hanging drop mount:-uses a depression slide , vaseline and a coverslip -the sample is suspended from the coverslip |
question
| What's positive staining |
answer
| positive staining the dye sticks to the specimen to give it color |
question
| What's negative staining |
answer
| the dyd does not stick to the specimen, instead it settles around the boundaries, creating a silhouette. ---heat fixation not requires, so there is less shrinkage or distortion of cells. |
question
| WHy do we stain microbes |
answer
| Most microbes-colorless very small and difficult to see Staining increases contrast' Sometimes increase size |
question
| Describe simple stains: give example? |
answer
| simple stains-require only a single dye. examples include malachite green, crystal violet, basic fuchsin and safranin all cells appear the same color vut can reveal shape, size, and arrangement |
question
| Differential stains |
answer
| use two differently colored dyes, the primary dye and the counterstain-distinguishes between cell types or parts Examples include Gram, acid-fast and endospore stains |
question
| When gram staing gram positive is what color |
answer
| gram positive (purple) |
question
| when gram staining gram negative stains are what color? |
answer
| gram negative (red) |
question
| What is the most universal dianostic staining technique for bacteria? |
answer
| Gram Staining |
question
| Isolation |
answer
| SEPERATING ONE SPECIES FROM ANOTHER Seperation of cells by spreading or dilution on agar medium |
question
| Describe Inspection- |
answer
| The colonies or broth culture are observed for growth characteristics, color, texture and size. that could be useful in analyzing the specimen content. Slides are made to assess microscopic details such as cell shape, size and motility. Stains can be used to gather information on microscopic morphology. Looking at the bacteria |
question
| Decribe identification? |
answer
| This is the major purpose of the 5 I's to determine the microbe, usually to the level of species. identify what your looking for. |
question
| What does the loop to loop isolation method allow? |
answer
| Allows you to quantify the number of bacteria present in a sample. |
question
| When might you use a spread plate instead of a streak plate? |
answer
| easier with liquid than solid. |
question
| Describe the gram stain? |
answer
| The most widely used staining methosd in microbiology. It is a differential stain because it divides bacteria into two classes: gram + and gram - |
question
| Acid -fast staining. Red cells areBlue cells are? |
answer
| Important diagnositc stain. acid-fast bacteria is pink/red non-acid fast bacteria (blue) |
question
| Describe special stains and give examples |
answer
| Special stains are used to emphaze certain cell parts that aren't revealed by convential staining methods. Example -capsule -flagellar staining -endospore staining (*significant for medical microbiology-distinguishes between the stores and cells they come from) |
question
| Describe 2 key characteristics of microscopes? |
answer
| Maginification and reolving power |
question
| Describe maginification |
answer
| -results when visible light wave pass through curve lens. light experiences refraction. Image is formed and enlarged |
question
| maginification occurs in two phases |
answer
| Objective lens forms real images ocular images forms virtual images |
question
| resolution |
answer
| the ability to distinguish adjacent objects or points from one another |
question
| resolving power |
answer
| resolving power = wavelength in light in nm 2X numerical aperture of objective lens |
question
| What kind of wavelengths provide a better resolution? |
answer
| Shorter |
question
| Numerical aperature? |
answer
| describe the relative efficiency of a lens in bending light rays |
question
| Increased magnification decreases? |
answer
| resolution |
question
| Describe oil immersion lens? |
answer
| immersion oil reduces refraction light; gathers more light resolution improved |
question
| describe fixed/stained smears |
answer
| smear developed by Robert Koch; spread thin film made from a liquid suspension of cells and air dying it. Heat the smear, and staining allows cells to stand out. |
question
| What sort of microscopes do we commonly use in the laba. simple b. electron c. phase contrast d. compund |
answer
| D. Compound ---occular and objective lens |
question
| Name three basic differences between inoculation and contamination? |
answer
| It's mostly a matter of extent. Inoculation is simply exposure. Contamination is not so controlled and usually far more harmful. |
question
| Describe how an isolated colony forms? |
answer
| Isolated colonies of bacteria are the result of a single bacterium which has replicated many times and eventually formed a visable lump of genetically identical bacteria. |
question
| explain why an isolated colony and a pure culture are not the same thing |
answer
| A pure culture is a microbial culture of only one organism. A microbial culture could contain any number of organisms. Rate This Answer |
question
| why are some bacteria difficult to grow in the lab? |
answer
| Different bacteria grow in different conditons, such as inside different cells, or under temperature conditions. So to produce certain bacteria growths, will need other things inside a petri dish. So it will become very awkward, or even impossible. |
question
| why are viruses hard to cultivate in the lab? |
answer
question
| how would you prove a resistant to antibotics using lab culture techniques? |
answer
| Any use of antibiotics can increase selective pressure in a population of bacteria to allow the resistant bacteria to thrive and the susceptible bacteria to die off. |
question
| Describe the medium mannitol salt agar |
answer
| selective medium differential medium complex medium |
question
| Describe chocolate medium? |
answer
| enriched medium complex medium |
question
| Describe MacConkey agar? |
answer
| selective medium differential medium complex medium |
question
| Describe nutrient broth? |
answer
| general-purpose medium complex medium |
question
| Describe Sabouraud's agar? |
answer
| selective medium complex medium |
question
| triple-sugar iron agar |
answer
| differential medium general-purpose medium complex medium |
question
| SIM medium |
answer
| differential medium general-purpose medium complex medium |
question
| Do virsus multiple? |
answer
| No |
question
| What degree do you incubate? How to microbes eat? |
answer
| 37Degree celcius microbes eat the nutrients at the bottom |
question
| describe aerobic microbes, what do you do so they won't sufficate? |
answer
| they need oxygen, you shake them so you won't sufficate them |
question
| Describe streak plate isolation method? |
answer
| loop and then dip it into solution and spread it on the plate in a pattern, sterilize the loop and spread the microbes again and repeat the process. |
question
| Describe why you would spread the plate? |
answer
| counting - creating a lawn or blanket of bacteria- liquid culture. This is easier with liquid than solid |
question
| how do you make "chocolate agar'? |
answer
| take blood and heat it |
question
| Leeuwenhoek used wht kind of _____microscope |
answer
| simple |
question
| Hooke used an ____microscope |
answer
| compound |
question
| which microscope has a sharp picture and image |
answer
| electron microscope and it has sharp picture image |
question
| describe endospore staining? |
answer
| bacteria form a seed inside itself. |
