Chapter Three (quiz two) – Flashcards
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| The Five I's (how to culture and characterize microbes) |
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| 1. Inoculation 2. Incubation 3. Isolation 4. Inspection 5. Identification |
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| Inoculation? |
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| Sample is place into a container of sterile medium contain appropriate nutrient to sustain growth |
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| Incubation? |
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| Incubator creates proper growth temperature to promote multiplication of microbes |
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| Isolation? |
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| Separation of cells by of cells by spreading or dilution on agar medium |
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| Inspection? |
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| Growth is observed |
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| Identification? |
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| What type of microb is it? |
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| Streak plate isolation method? |
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| [image] |
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| Loop Dilution Isolation method? |
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| AKA Pour plate technique. this method allows you to quantify the number of bacteria present in a sample. Anaerobic bacteria can grown really well with this technique |
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| Spread plate isolation method use? |
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| used in clinical setting to see if the whole sample has growth ex. cerebrospinal fluid count all the colonies for a given sample |
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| Ways to categorize media? (3) |
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| 1. Physical State 2. Chemical Composition 3. Functional Type |
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| Physical States of Media (3) |
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| 1. Liquid Media 2. Semisolid Media 3. Solid Media |
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| Liquid Media? |
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| Water-based solutions, do not solidify at temperatures above freezing -broths, milks, or infusions -growth seen as cloudiness or particulates |
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| Semisolid Media? |
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| Clot like consistency at room temperature -used to determine motility and to localize reactions at specific site |
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| Solid Media? |
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| Firm surface surface on which vells can form discrete colonies -liquefiable and nonliquefiable -useful for isolating and culturing bacteria and fungi |
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| Chemical Content of Media (2) |
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| -Defined or synthetic media - complex or non-synthetic media |
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| Defined or Synthetic Media? |
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| compositions are precisely chemically defined -recipe, amount of every component |
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| Complex or Non-synthetic Media? |
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| if even just one component is not chemically definable ex. brain extract heart extract |
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| Functions of Media? (7) |
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| -general purpose -enriched -selective -differential -reducing -carbohydrate fermentation -Assay |
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| general purpose media? |
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| to grow as broad a spectrum of microbs as possible. -usually non synthetic -contain a mixture of nutrients to support a variety of microbes ex. nutrient agar |
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| Enriched Media? |
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| contains complex organic substances (growth factors) to support growth of fastidious bacteria ex. blood agar |
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| What are Fastidious Bacteria? |
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| bacteria that require growth factor or other complex substances to grow |
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| Selective Media? |
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| contains one or more agents that inhibit the growth of certain microbes but not others -zone of death - contain antibiotics ex. MacConkey agar |
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| Differential Media? |
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| Allow multiple types of microorganisms to grow but display visible differences among those microorganisms ex. also MacConkey agar |
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| Reducing Media? |
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| absorbs oxygen or slows its penetration in the medium; used for growing anaerobes or for determining oxygen requirements |
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| carbohydrate fermentation media? |
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| contain sugars that can be fermented and a pH indicator; useful for identification of microoganisms |
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| Assay Media? |
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| used to test the effectiveness of antibiotics, disinfectants, antiseptics |
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| Two Phases of Magnification with Light Microscopy? |
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| -Objective lens: forms the real image -Ocular lens: forms the virtual imagae total power of magnification- the product of the power of the objective and the power of the ocular |
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| Define Resolution! |
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| the ability to distinguish two adjacent objects of points from one another |
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| Three Elements of good Microscopy |
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| 1. Magnification 2. Resolution 3. Contrast |
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| Increased Magnification ________ the resolution |
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| decreases |
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| How do you get higher resolution at higher magnifications? |
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| adjusting the amount of light entering the condenser using an adjustable iris diaphragm or using special dyes help increase resolution at higher magnifications |
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| How does the Oil Immersion Lens work? |
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| -reduces refraction of light -more light is gathered -resolution is improved |
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| Microscopy Examples (4) |
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| -bright field -dark field -phase contrast -fluorescence |
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| Bright-field microscopy? |
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| -most widely used -forms image when light is transmitted trough specimen -can be used with live, unstained and preserve, stain specimens |
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| Fluorescence Microscopy? |
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| Forms a colored image against a black field |
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| Electron Microscopy? |
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| -focused electron beam -offers much better resolution -samples are dead |
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| How does wavelength effect resolution? |
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| the shorter the wavelength the better the resolution |
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| Wet Mount? |
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| cells are suspended in fluid, a drop or two of the culture is then placed on a slide and overlaid with a cover glass |
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| Hanging drop mount? |
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| -uses depression slide, Vaseline and coverslip -sample is suspended from the coverslip |
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| Smears? |
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| Developed by Robert Koch -spread a thin flim made from a liqiud suspension of cells and air drying it -heat the smear (heat fixation) -some are fixed using chemicals |
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| Basic Dyes? |
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| Cationic bind to negatively charged substances |
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| Acidic Dyes? |
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| Anionic bind to positively charged substances |
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| What does staining do? |
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| increases the contrast |
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| Positive Staining? |
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| the dye sticks to the specimen to give it color -heat fixation is required |
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| Negative Staining? |
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| the dye does not stick to the specimen, instead it settles around its boundries creating a silhouette -heat fixation is not required |
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| Advantage of not heat fixating? |
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| there is less shrinkage or distortion of cell |
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| Simple Stains? |
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| require only a single dye -cells appear the same color but can reveal shape, size, and arrangement ex. crystal violet |
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| Differential Stains? |
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| Use two differently colored dyes, the primary dye and the counter-stain -distinguishes between cell types or parts ex. Gram |
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| Gram Stain? |
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| Most universal diagnostic staining technique for bacteria -differentiation of microbes as gram positive or negaitve |
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| Acid-fast staining? |
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| Acid fast bacteria from non acid fast bacteria Important in medical microbiology (mycobacterium is acid fast) Tests for Mycolic Acid- these stay pink and are acid fast |
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| Examples of Special Stains? (3) |
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| 1. Capsule Staining 2. Flagellar Staining 3. Endospore: distinguished between the spores and the cells they come from |
