Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Ch 2 tools of the lab microbio > tools of the lab > Flashcards

tools of the lab Flashcards

1
Q

the five I’s of microbio

A

inoculation
incubation
isolation
inspection
identification

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

inoculation

A

culture: to grow microorganisms

medium (pl. media): nutrients for the growth of microbes

inoculum: a small sample of microbed

inoculation: the intro of an inoculum into media to culture microbes

clinical specimens are obtained from body fluids, discharges, anatomical sites, or diseased tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

incubation

A

incubator: a temp-controlled chamber to encourage the multiplication of microbes

temps used in lab propagation of microorganisms

20-45 degrees C

atmospheric gases such as O or CO2 may be required for the growth of certain microbes

during the incubation period the microbe multiplies and produces growth that is observable macroscopically

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

3 physical states of media

A

liquid

semisolid

solid (can be converted to liquid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

agar

A

complex polysaccharide isolated from Gelidium

solid at room temp

liquefies at 100 degrees C
solidifies at 42 degrees C

flexible and moldable

not a digestible nutrient for most microorganisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

defined or synthetic chemical content of media

A

composition is precisely chemically define

contain pure organic and inorganic compounds that vary little from one source to another

molecular content specified by means of an exact formula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

complex chemical content of media

A

one or more components is not chemically defined

contains extracts of animals, plants, or yeasts

blood, serum, meat extracts or infusions, milk, yeast extract, soybean digests, and peptone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

general purpose media

A

grow as broad a spectrum of microbes as possible

generally complex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

enriched media

A

contains complex organic substances such as blood, serum, hemoglobin, or special growth factors for the growth of fastidious microbed

used in clinical lab to encourage growth of pathogens present in low numbers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

selective media

A

contains one or more agents that inhibit the growth of a certain microbe(s)

important in isolation of a specific type of microorganism

speed up isolation by suppressing unwanted organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

differential media

A

all multiple types of organisms to grow but display visible differences in how they grow

variations in colony size or color

media color changes

production of gas bubbles

variations often come from chemicals in the media with which microbes react

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

a medium can be both selective and differential

A

ex. MSA EMB MacConkey agar

dyes are used as differential agents because many are pH indicators that change color in response to the production of an acid or a base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

reducing medium

A

contains a substance that absorbs oxygen or slows the penetration of oxygen

important for growing anaerobic bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

carb fermentation media

A

contains sugars that can be fermented with a pH indicator to show this reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

isolation

A

based on the concept that if an individual bacterial cell is seperated from other cells on a nutrient surface it will produce a discrete mound of cells called a colony

requires: a medium with a firm surface
a petri dish
an inoculating look (streak plate method)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

colony

A

a macroscopic cluster of cells appearing on a solid medium arising from the multiplication of a single cell

17
Q

microbes can be identified through

A

microscopic appearance

characterization of cellular metabolism

determination of nutrient requirements, products given off during growth, presence of enzymes, and mechanisms for deriving energy

genetic and immunologic characteristics

18
Q

microbial size

A

yeast are generally 3 to 4 um

the smallest bacteria measure around 200 nm; largest around 750 um

most virsues measure between 20nm and 400nm; some can be as big as 800nm or 1500nm 9as big as cells)

19
Q

bright-field microscopy

A

the most widely used type of light microscope

forms its image when light is transmitted through the speciman

the speciman being denser and more opaque than its surroundings, absorbs some of this light, and the rest of the light is transmitted directly up through the ocular

can be used for both live, unstained material and preserved stained material

20
Q

dark-field microscopy

A

A bright-field microscope can be
adapted as a dark-field microscope by
adding a special disc called a stop to
the condenser

  • The stop blocks all light from entering
    the objective lens, except peripheral
    light that is reflected off the sides of
    the specimen itself
  • The resulting image is a particularly
    striking one: brightly illuminated
    specimens surrounded by a dark
    (black) field
  • The most effective use is to visualize
    living cells that would be distorted by
    drying or heat or that cannot be
    stained with the usual methods
21
Q

phase contrast microscopy

A

The phase-contrast microscope has
been constructed to take advantage
of the fact that cell structures differ in
density
* Contains devices that transform the
subtle changes in light waves
passing through the specimen into
differences in light intensity
* The amount of internal detail visible
by this method is greater than by
either bright-field or dark-field
methods
* Most useful for observing intracellular
structures such as bacterial
endospores, granules, and
organelles, as well as the locomotor
structures of eukaryotic cells such as
cilia

22
Q

fluorescence microscopy

A

The fluorescence microscope is a specially
modified compound microscope furnished
with an ultraviolet (UV) radiation source
* The name comes from the use of certain
dyes (acridine, fluorescein) and minerals
that are fluorescence. The dyes emit
visible light when bombarded by short
ultraviolet rays.
* For an image to be formed, the specimen
must first be coated or placed in contact
with a source of fluorescence
* Shining ultraviolet radiation on the
specimen cause it to give off light that will
form its own image, usually an intense red,
blue, or green against a black field
* Has its most useful applications in
diagnosing infections and pinpointing
particular cellular structures

23
Q

transmission electron microscope (TEM) micrscopy

A

TEM - the method of choice for
viewing the detailed structure of cells
and viruses
* Produces its image by transmitting
electrons through the specimen
* Because electrons cannot easily
penetrate thick preparations, the
specimen must be sectioned into
extremely thin slices (20–100 nm
thick) and stained or coated with
metals that will increase image
contrast
* The darker areas of TEM micrographs
represent the thicker (denser) parts,
and the lighter areas indicate the
more transparent and less dense
parts

24
Q

scanning electron microscope (SEM) microscopy

A

SEM provides some of the most
dramatic and realistic images in
existence
* Designed to create an extremely
detailed three-dimensional view of
all kinds of objects, from plaque on
teeth to tapeworm heads
* SEM bombards the surface of a
metal-coated specimen with
electrons while scanning back and
forth over it
* A shower of electrons deflected
from the surface and the electron
pattern is displayed as an image
on a television screen
* The color is always added
afterward; the actual microscopic
image is black and white

25
Q

preparing specimans for the microscope

A

Specimens are generally prepared by mounting a sample on
a glass slide that sits on the stage between the condenser
and the objective
The manner in which a specimen is prepared depends on:

  • The condition of the specimen: living or dead
  • The aims of the examiner: observation of overall structure,
    identification, or movement
  • The type of microscopy available: bright-field, dark-field,
    phase-contrast, or fluorescence
26
Q

stains

A

Unstained cells in a fixed smear are difficult to see,
regardless of magnification and resolving power
Staining is any procedure that applies colored chemicals
(dyes) to specimens:
* Basic dyes have a positive charge
* Acidic dyes have a negative charge
Bacteria have numerous negatively charged substances and
attract basic dyes
Acidic dyes are repelled by cells

27
Q

fixation process

A

Staining increases visibility of specimen
* Most cells are colorless!
Accentuates specific morphological features
* Stains may bind to specific cellular structures, like
flagella
Fixation of specimens preserves them
* Dead cells would otherwise auto-lyse soon after they
die

28
Q

dyes and stains

A

Makes internal and external
structures more visible by
increasing contrast with
background
Ionizable dyes have charged
groups
* Basic dyes have positive
charges
* Acidic dyes have negative
charges

29
Q

Negative versus Positive Staining

A

Positive stain: dye sticks to the specimen and gives it color
Negative stain: does not stick to the specimen but settles
some distance from its outer boundary, forming a silhouette:
* Negatively charged cells repel the negatively charged dye
and remain unstained
* Smear is not heat fixed so the distortion and shrinkage of
cells is reduced
* Also used to accentuate a capsule
* Nigrosin and India ink are used

30
Q

simple stains

A

only require a single dye and an
uncomplicated procedure:
* Cause all the cells in the smear to appear more or less the
same color, regardless of type
* Reveal shape, size, and arrangemen

31
Q

differential stains

A

Use two differently colored dyes: the primary dye and the
counterstain
* Distinguish cell types or parts
* More complex and require additional chemical reagents to
produce the desired reaction
Copyright

32
Q

differential stains: the gram stain

A

Developed in 1884 by Hans Christian Gram
Consists of sequential applications of:
* Crystal violet (the primary stain)
* Gram’s iodine (the mordant)
* An alcohol rinse (decolorizer)
* A contrasting counterstain (for example Safranin)

33
Q

gram stain

A

Most widely used
differential staining
procedure
Divides bacteria into two
groups based on
major differences in their
cell wall structure:
Gram + bacteria =
purple
Gram - bacteria =
pinkish red

34
Q

differential stains: acid fast stain

A

Differentiates acid-fast bacteria (pink)
from non-acid-fast bacteria (blue)
Originated as a method to detect
Mycobacterium tuberculosis:
* These bacteria cell walls have a
particularly impervious cell wall
(mycolic acids) that holds fast
(tightly or tenaciously) to the dye
(carbol fuschin) when washed
with an acid alcohol decolorizer
Also used for other medically
important bacteria, fungi, and
protozoa

35
Q

differential stains: endospore stain

A

Similar to the acid-fast
stain in that a dye is forced
by heat into resistant
bodies called endospores
* Stain distinguishes
between endospores and
vegetative cells
* Significant in identifying
gram-positive, spore-
forming members of the
genus Bacillus and
Clostridium
Copyright

36
Q

special stains: capsule stain

A

Used to emphasize cell parts
that are not revealed by
conventional staining methods
Capsular staining:
* Used to observe the
microbial capsule, an
unstructured protective layer
surrounding the cells of
some bacteria and fungi
* Negatively stained with India
ink

37
Q

special stains: flagellar stain

A

Used to reveal tiny,
slender filaments used by
bacteria for locomotion

Ch 2 tools of the lab microbio (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions