CHAPTER 2 Flashcards
five i’s of microbology
inoculation
incubation
isolation
inspection
identification
to culture something means
to grow organisms
medium
nutrients for the growth of microbes
inoculum
a small sample of microbes
inoculation
the introduction of an inoculum into media to culture microbes
where are clinical specimens obtained form
bodily fluids, discharges, diseased tissues, anatomical sites
whats an incubator?
a temperature controlled chamber to encourage the multiplication of microbes
what temperatures are used in lab propagation of micro organisms
20-45 c or 68-113 F
atmospheric gases such as ___ or ____ may be required for the growth of certain microbes
oxygen or carbon dioxide
t/f after incubation you still can macroscopically see any growth
FALSE you can see with plain eye
3 states of media are
physical state ( solid, liquid)
Chemical Composition (Defined/Synthetic, Complex)
Functional Type
what are the three physical states of media
liquid
semi solid
solid (soil that can be converted to liquid + solid that can not)
agar is made from
a complex polysaccharide isolated from Gelidium
t/f agar is solid at room temperature
true
what temperature does agar liquidify
100 C or 212F
what temperature does it solidify
42c (107.6F)
___ medium is flexible and moldible
agar
t/f agar is digestible for most microorganisms
false
whats a defined/synthetic media
composition is precisely chemically defined
contains pure organic and inorganic compounds that vary little
molecular content is exact, exact formula
what is complex media
one or more components is not chemically defined
contains extracts of animals, plants or yeasts
ex. blood, serum, meat extracts or infusion, milk yeast peptone
whts teh opposite of complex media
defined/synthetic
a media to grow a broat spectrum of microbes is a _____
broad spectrum media
t/f broad spectrum media are synthetic/defined
false. complex
enriched media is an example of _____ media
complex
enriched media contains complex organic substances (blood, serum, hemoglobin) or special growth factors for the growth of ______ microbes
fastidious
what type of media is used in the laboratory to encourage growth of pathogens present in low numbers
enriched media
_____ contains one or more agents that inhibit the growth of a certain microbe of microbes and favoring the growth of desired ones
selective media
a ____ media is important in isolation of a specific type of microorganism from a sample containing dozens of different species
selective
is MacConkey Agar a selective or differential media
BOTH
Selective:
MacConkey Agar selects for Gram negative enterics (bacteria in intestinal track) (E.coli)
Differential: The medium provides lactose and a pH indicator, allowing for differentiation; lactose fermenters produce acid, resulting in phenol red turning pink colonies, while non-fermenters remain colorless.
how is SIM Sulfur Indole Motility (SIM) a differential media
Sulfur Indole Motility (SIM) medium is differential because it allows for the identification of bacteria based on three characteristics:
Sulfur Reduction: Some bacteria can reduce sulfur to hydrogen sulfide (H₂S), which reacts with iron salts in the medium to form a black precipitate. This indicates sulfur reduction.
Indole Production: After incubation, the addition of Kovac’s reagent reveals indole production. If the organism can convert tryptophan to indole, a red ring forms at the top of the medium.
Motility: SIM medium is semi-solid, allowing motile bacteria to spread from the stab line, resulting in turbidity throughout the medium. Non-motile bacteria will only grow along the stab line.
is Blood agar selective or differential
Blood agar is a differential medium because it can distinguish between different types of bacteria based on their ability to lyse red blood cells and degrade hemoglobin. It contains intact red blood cells, and bacteria that produce hemolysins can break down these cells, resulting in visible changes in the aga
CNA Agar is differential of selective
selective for Gram positive cocci
Mannitol Salt Agar (MSA) is selectie or differential
BOTH
Selective for Staphylococcus species because high salt content adn many cant grow (halophile species can )
Differential - mannitol fermenters vs non. Fermenters = acidic red to yellow ph indicator (phenol red)
Sabouraud’s Agar is selective or differential
Selective for Fungi
_______ media allow multiple organisms to grow but display the visible differences in how they grow
differential
Media color changes is an example of ___ media
differential
t/f production of gas bubbles is an example of selective media
differential
reducing medium
contains a substance that absorbs oxygen or slows the penetration fo oxygen
Thioglycolic acid broth is good for growing ______
anaerobs
reducing medias are important for growing
anaerobic bacter
what is transport media used for
maintain and preserve specimens that have to be held for a long time before clinical analysis (chemicals in it maintain species for longer)
what is the red showing
red is the lactose fermentors,
whitish are not
differential media- MacConkey Agar
phenol red
Carbohydrate Fermentation Media is esentially a ____ broth
nutrient broth
what is carbohydrate fermentation media
liquid that contains sugars that can be fermented with a pH indicator to show reaction (sucrose and manitol)
with fermentation, color change red - yellow as well as air space to show if organism produces gas (o2) (DIFFERENTIAL MEDIA)
what is the pH indicator in carbohyrate fermentation media
phenol red … turns red to yellow
assay media is used for
testing the effectiveness of antimicrobial drugs
what si enumeration media used for
industrial and enviornmental microbologists to count the numbers of organisms in milk, water, food soil
Whats a colony forming unit
a term used to more appropriately describe that a colony might have been formed by more than one cell of the same species
t/f only sterilize loop after first inoculation
what is this called
false after each step
streak plate
what is this called
pour plate/loop dilution
what is this called
spread plate
microbes can be identified through
- Microscopic appearance
- characterization of cellular metabolism (methobolic pathways - do they produce enzymes or not)
- determination of nutrient requirements, products given off during growth
- presence of enzymes and mechanisms for deriving energy
genetic adn immonological chatacteristcs
dimentionals of microscopic organisms range from
mm, um and nm
(cm, m = macro)
1um = 1000 nm
1um = .001 mm
protozoa and algae are on average what size
3-4 mm
yeasts are generally what size
3-4 um
the smallest bacteria are ___ and largest are ____
200nm - 750 um
t/f viruses are larger than bacteria
FALSE - much much smaller with very few exceptions
how big are viruses
20nm and 400nm (MOST)
some as big as 800 - 1500 nm
real image is formed by the ____
objective lens
virtual image is formed _____
when the image is projected up through teh microscope body to the plane of the eye piece the occular lens forms a second image
resolving power also known as
resolution
resolving power of human eye
.2mm
resolving power or the light microscope using oil immersion
.2um
t/f with oil immersion 90% of light rays pass up through objective lens
false - 100%
refractive index
degree of bend that light undergoes as it passes from one medium to the next
t/f the HIGHER the difference in the refractive indexes (more bending of light) the sharper the contrast registered by the microscope
TRUE
t/f too much light can reduce contrast and burn out the image.
how do you control this
true
iris diaphphragm
Use the ______ to control the amount of light coming into the _____.
iris diaphragm, condensor
type of microscope that forms an image when light is transmitted through the specimen
bright field microscope
a brihgt field microscope can be adapted as a dark field microscope by adding a disc called a ____ to the condensor
stop
what does a stop do?
blocks all light from entering the objective lens, except the peripheral light that is reflexted off the sides of the specimen itself. creates a beautiful illuminated specimen around a dark field
when to use a dark field microscope
to visualize living cells that would be distorted by drying or heat or that cannot be stained with the usual methods
what microscope is this image from
bright field scope
versitile microscope, live dead, unstained, stained
bright field
what microscope is this from
darkfield scope
what microscope
phase contrast
what does the phase contrast microscope take advantage of
the fact that cell structures differ in density
________ microscope contains devices that transform the subtle changes in light waves passing though the specimen into differences in light intensity
phase contrast
the detail visable by this method of miscropy is greater than that of bright or dark field
phase contrast
what is phase contrast most useful for observing
intracellular structures (ornganelles, granules, bacterial endospores
_____ overcomes the problem of cells or structures being too thick by using a laser beam of light to scan various depths inteh specimen and deliver a sharp image
confocal
what microscope is able to capture highly focused view at any level of the cell
confocal
the _____ microscope is a specially modified compound microscope furnished with an UV radiation source
fluorescnece
for an image to be formed in fluorescence microscope must be coated in ____ and UV lights it up
fluorescence
most useful applications in fluorescence microscopy is diagnosing _______ and pinpointing ________
infections, particular cellular structures (pathogy labs, diagnostics)
what microscope
fluorescence
what microscope
confocal
for viewing the detailed structure of the cells and viruses use the ______ microscope
Transmission electron microscope
how does the TEM microscope work
by transmitting electrons through the specimen
t/f because they are electrons, the TEM microcscope can easily penetrate thick preparations
FALSE - must be sectioned into extremely thin slices (20-100nm) and stained or coated with metals that increase image contrast
what microscope
Transmission electron microscope
what are the dark adn light parts
dark = dense part of cell and light = more transparents, less dense
what microscope creates the most dramatic and realistic image
scanning electron microscope ( SEM)
what microscope creates this
SEM scanning electron microscope
consists of a drop or two of culture placed on a slide and overlaid with a cover slip
wet mount
a drop of culture is placed in a concave (depression) slide. vasaline adhesive or sealant and a cover slip are used to suspend the sample
hanging drop
two fresh living preparation techniques
hanging drop, and wet mount
t/f unstained cells in a fixed smear are difficult to see regardless of magnification and resolving power
true
basic dyes have a ____ charge
positive (cationic)
acidic dyes have a ___ charge
negative (anionic)
only SOME bacteria have a negative charge
FASE ( all bacteria)
_______ stain dye sticks to the specimen and gives it color
positive
when dye does not stick to the specimen but settles some distance from its outer boundary (forms silhouette) we call this a
negative stain
in a negative stain we ALWAYS heat fix
FALSE ( not heat fixed so the distoration adn shrinkage of cells is reduced)
t/f negative stain keep accurate shape of cell
TRUE - no heat fixing
____ stains are used to accentuate a capsule
negative stains
t/f simple stains require two dyes
false - single dye
_____ stains cause all the cells in the smear to appear the same color regardless of type,
simple
_____ stains reveal shape, size, arrangement
simple
_____ stains use two differently colored dyes the primary dye and counter stain
differential stain
what type of stain is used to distinguish cell types or parts
differential
what is a capsule mad from
thick polysaccharide coating
when were differential stains developed
1884 Hans christian Gram
what two stains are used for negative stain?
Nigrosin and India ink
what is the primary stain in gram staining
Crystal violet
what is the mordant in gram staning
Gram’s iodine, allows primary stain to form insoluble complex in peptidoglycan so to not leak out
what is the decolorizer in gram staining
alcohol
what is the counter stain in gram staining
ex. Safranin
t/f ALL bacteria can be categorized as gram + or gram -
false - most bacteria
t/f gram staining has everything to do with the charge of the cell
false - has to do with the cell wall
_____ stain remains the universal basis for bacterial classification and identification
gram staining
what does acid fast mean
acid resistant
what type of stain is acid- fast
differential
what does acid-fast stain do
differentiates acid fast (acid resistant) bacteria vs not
how did acid fast stain originate?
as a method to detect Mycobacterium tuberculosis
what does Mycobacterium tuberculosis do when acid-fast stained?
their cell wall holds fast (tightly) to the dye carbolfuchsin) when washed with an acid decolorizer (acid resistant)
what bacteria is acid fast
Mico (genus), and Norcardia both are pathogens
what dye is used in acid-fast staining
carbolfuchsin
endospore is a _____ stain
differential
both acid-fast staining and endospore staining dye is forced by _____ into resistant bodies
heat
what does endospore stain do
stain distinguishes between endospores and vegetative cells
t/f a vegetative cell contains an inner spore
fa;lse
endospore stain is significant in identifying GRAM +, spore forming members of genus ________ and ___________
Bacillus and clostridium
shape of gram - cells
shape of gram + cells
rods , the red
cocci, purple
what stain is this and what does blue and purple represent
acid fast,
blue = not acid fast (not acid resistant)
purple = acid fast (holds dye in cell wall even w acidic decolorer)
what are special stains
used to emphasize cell parts that are not revealed by conventional staining methods
two examples of special stains
capsular staining and flagellar staining
what stain is this adn what are the colors
endospore, endospores are green, and vegetative cells pink
what stain is this
capsule stain with india ink
what stain is this
flagellar
what stain is campsule stain
differential
what stain is acid fast stain
differential
what stain is crystal violet
simple
what stain is gram stain
differentialha
what stain is flagellar
special
