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Microbiology WJC Chpt 3 2013
Tools of the Lab
97
Microbiology
Undergraduate 1
01/28/2013

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Term
Explain what the five I's mean and what each step entails?
Definition
-Inculation
-Incubation
-Isolation
-Inpection
-Identification
Term
The term "culture" refers to the _____growth of microorganisms in ____.
a. rapid, an incubator
b. macroscopic, media
c. microscopic, media
d. artifical, colonies
Definition
b. macroscopic, media
The term "culture" refers to the macroscopic growth of microorganisms in media.
Term
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
Definition
A mixed culture is____.

c. one that contains two or more known species.
Term
Resolution is ____with a longer wavelength of light.
a. improved
b.worsened
c. condenser
d. eye
Definition
Resolution is ____with a longer wavelength of light.
b.worsened
Term
A real image is produced by the
a. ocular
b. objective
c. condenser
d. eye
Definition
A real image is produced by the objective
Term
A microscope that has a total magnification of 1,500X when using the oil immersion objective has an ocular of what power?
a. 150X
b. 1.5X
c. 15X
d. 30X
Definition
c. 15 X

Know how to do the formula!!!!
Term
The specimen for an electron microscpe is always :
a. strained with dyes
b. sliced into thin sections
c. killed
d. viewed directly
Definition
c. killed
Term
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
Definition
Bacteria tend to stain more readily with cationic (positively) charged dyes because bacteria

b. contains a large amount of acidic sunstances
Term
Describe Inculation
Definition
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.
Term
Incubation
Definition
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.
Term
What term is used to describe a pile of microbes that is visible to the naked eye?
a. plaque
b. hive
c. colony
d. Thallus
Definition
term is used to describe a pile of microbes that is visible to the naked eye?
c. colony
Term
What is media contained in?
Definition
test tubes
flasks
petri dishes
Term
how many different types of media?
Definition
At least 500 different
Term
List the three classifications of Media
Classification
Definition
Physical state
chemical composition
functional type
Term
List the physical state of media classification
Definition
1. liquid
2. semisolid
3. solid (can be covereted to liquid)
4. solid (cannot be liquidified)
Term
Chemical composition media list two types?
Definition
1. Synthetic (chemically defined)
2. Nonsynthetic (complex, not chemically defined)
Term
List 8 functional types of media
Definition
1. general purpose
2. enriched
3. selective
4. differential
5. anaerobic growth
6. specimen transport
7. assay
8. enumeration
Term
List the 3 physical states of media?
Definition
1. liquid media
2. semisolid media
3. solid media
Term
Describe liquid media?
give examples?
How do you know their is growth?
Definition
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
Term
Describe semi-solid media:
--used to what?
Definition
clot -like consistency at room temperature
used to determine motility and to localize reactions at specific site
Term
Describe solid media-
why is it useful?
Definition
Solid media is a firm surface on which cells can form discrete colonies.
Liquefiable and nonliquiuefiable
Useful for isolating and culturing bacteria and fungi
Term
Chemical content of defined or synthetic media?
Definition
defined or synthetic media-compositions are precisely chemically defined
Term
Chemical content of media that is complex or nonsynthetic media?
Definition
complex or nonsynthetic media -if even just one component is not chemically definable
Term
Describe general purpose media- (function)
Examples
Definition
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)
Term
a fatidious organism must be grown on what type of medium?
Definition
synthetic medium and enriched medium
Term
True or false

A subculture is a culture made from a isolated colony
Definition
True
Term
True or false:
Agar has the disadvantage of being easily decomposed by microorganisms.
Definition
False
Agar IS NOT easily decomposed by microorganisms (gelatin can be)
Term
True or False

The factor that most limits the clarity of an image in a microscope is the magnification
Definition
FALSE
The factor that most limits the clarity of an image in a microscope is the RESOLUTION
Term
True or False

Living speimens can be examined either by light microscopy or electron microscopy
Definition
FALSE:
Living specimens can be examined with phase -contrast or differential interference microscopy
Term
True or False

The factor that most limits the clarity of an image in a microscope is the magnification
Definition
FALSE
The factor that most limits the clarity of an image in a microscope is the RESOLUTION
Term
True or False

Living speimens can be examined either by light microscopy or electron microscopy
Definition
FALSE:
Living specimens can be examined with phase -contrast or differential interference microscopy
Term
True or False

The best strain to use to visualize a microorganism with a large capsule is a simple strain
Definition
False:

The best strain to use to visualize a microorganism with a large capsule is a NEGATIVE strain
Term
Describe Enriched media

Give Examples
Definition
Contains complex organic substances (growth factors-vitamins, amino acids)to support growth of fastidious bacteria
Example: blood agar, Thayer-Martin medium (chocolate agar)
Term
Describe Selective media
give examples
Definition
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
Term
Differential media- Describe and give example
Definition
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.
Term
Describe reducing media and what it is used for?
Definition
reducing media- absorbs oxygen or slows its penetration in the medium; used for growing anaerobes or for determing oxygen requirements
Term
Carbohydrate fermentation media- describe--what is it used for?
Definition
carbohydrate fermentation media-contain sugars that can be fermented and a pH indicator; useful for identification of microorganisms
Term
Describe assay media- used to test?
Definition
assay media-used to test the effectiveness of antibiotics, disinfectants, antiseptics
Term
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
Definition
B. Differential
Term
Why do we use immersion oil with our 100X objective lenses?
a. reduce light scatter
b. reduce ilumination
c. reduce maginification
d. Reduce contrast
Definition
a. reduce light scatter
Term
Describe Bright-Field microscopy?
Definition
-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
Term
Describe Flurorescence microscopy?
Definition
-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
Term
electron microscopy
Definition
-Focused electon beam
-Wavelength=6pm
-1000,000 X less than red visible light
offers better resolution
-samples are dead
Term
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)
Definition
c. Violet
Term
What are the 2 living preparations in Lab?
Definition
wet mount

hanging drop mount
Term
Describe a wet mount?
Definition
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.
Term
Desccribe hanging drop mount?
Definition
Hanging drop mount:-uses a depression slide , vaseline and a coverslip
-the sample is suspended from the coverslip
Term
What's positive staining
Definition
positive staining the dye sticks to the specimen to give it color
Term
What's negative staining
Definition
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.
Term
WHy do we stain microbes
Definition
Most microbes-colorless very small and difficult to see
Staining increases contrast'
Sometimes increase size
Term
Describe simple stains:
give example?
Definition
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
Term
Differential stains
Definition
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
Term
When gram staing gram positive is what color
Definition
gram positive (purple)
Term
when gram staining gram negative stains are what color?
Definition
gram negative (red)
Term
What is the most universal dianostic staining technique for bacteria?
Definition
Gram Staining
Term
Isolation
Definition
SEPERATING ONE SPECIES FROM ANOTHER
Seperation of cells by spreading or dilution on agar medium
Term
Describe Inspection-
Definition
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
Term
Decribe identification?
Definition
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.
Term
What does the loop to loop isolation method allow?
Definition
Allows you to quantify the number of bacteria present in a sample.
Term
When might you use a spread plate instead of a streak plate?
Definition
easier with liquid than solid.
Term
Describe the gram stain?
Definition
The most widely used staining methosd in microbiology. It is a differential stain because it divides bacteria into two classes: gram + and gram -
Term
Acid -fast staining.
Red cells are?
Blue cells are?
Definition
Important diagnositc stain. acid-fast bacteria is pink/red
non-acid fast bacteria (blue)
Term
Describe special stains and give examples
Definition
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)
Term
Describe 2 key characteristics of microscopes?
Definition
Maginification and reolving power
Term
Describe maginification
Definition
-results when visible light wave pass through curve lens. light experiences refraction. Image is formed and enlarged
Term
maginification occurs in two phases
Definition
Objective lens forms real images
ocular images forms virtual images
Term
resolution
Definition
the ability to distinguish adjacent objects or points from one another
Term
resolving power
Definition
resolving power =
wavelength in light in nm
2X numerical aperture of objective lens
Term
What kind of wavelengths provide a better resolution?
Definition
Shorter
Term
Numerical aperature?
Definition
describe the relative efficiency of a lens in bending light rays
Term
Increased magnification decreases?
Definition
resolution
Term
Describe oil immersion lens?
Definition
immersion oil reduces refraction light; gathers more light resolution improved
Term
describe fixed/stained smears
Definition
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.
Term
What sort of microscopes do we commonly use in the lab?
a. simple
b. electron
c. phase contrast
d. compund
Definition
D. Compound ---occular and objective lens
Term
Name three basic differences between inoculation and contamination?
Definition
It's mostly a matter of extent. Inoculation is simply exposure. Contamination is not so controlled and usually far more harmful.
Term
Describe how an isolated colony forms?
Definition
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.
Term
explain why an isolated colony and a pure culture are not the same thing
Definition
A pure culture is a microbial culture of only one organism. A microbial culture could contain any number of organisms.
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Term
why are some bacteria difficult to grow in the lab?
Definition
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.
Term
why are viruses hard to cultivate in the lab?
Definition
Term
how would you prove a resistant to antibotics using lab culture techniques?
Definition
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.
Term
Describe the medium mannitol salt agar
Definition
selective medium
differential medium
complex medium
Term
Describe chocolate medium?
Definition
enriched medium
complex medium
Term
Describe MacConkey agar?
Definition
selective medium
differential medium
complex medium
Term
Describe nutrient broth?
Definition
general-purpose medium
complex medium
Term
Describe Sabouraud's agar?
Definition
selective medium
complex medium
Term
triple-sugar iron agar
Definition
differential medium
general-purpose medium
complex medium
Term
SIM medium
Definition
differential medium
general-purpose medium
complex medium
Term
Do virsus multiple?
Definition
No
Term
What degree do you incubate? How to microbes eat?
Definition
37Degree celcius microbes eat the nutrients at the bottom
Term
describe aerobic microbes, what do you do so they won't sufficate?
Definition
they need oxygen, you shake them so you won't sufficate them
Term
Describe streak plate isolation method?
Definition
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.
Term
Describe why you would spread the plate?
Definition
counting - creating a lawn or blanket of bacteria- liquid culture. This is easier with liquid than solid
Term
how do you make "chocolate agar'?
Definition
take blood and heat it
Term
Leeuwenhoek used wht kind of _____microscope
Definition
simple
Term
Hooke used an ____microscope
Definition
compound
Term
which microscope has a sharp picture and image
Definition
electron microscope and it has sharp picture image
Term
describe endospore staining?
Definition
bacteria form a seed inside itself.
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