Chapter 2 Flashcards
The visualization of bacteria required the use of a compound ____ microscope.
Light
The visualization organisms that fall in the range of nm (nanometers) requires the use of a ____ microscope.
Electron
The visualization of microorganisms that fall in the range of mm (milli-) can be seen by _____
The naked eye.
Dimensions of MACROscopic organisms are usually given in ___ and ___.
Centimeters (cm), meters (m)
Dimensions of most bacteria fall between ___ and ___ in size.
1 um - 10 um (micrometers)
The method of spreading a small culture sample over a medium in a pattern that gradually this out the sample - resulting in isolated colonies is called the _____ method.
Streak plate method
With the ___ ___ technique, a small vol. of liquid, diluted sample is pipetted onto the surface of the medium and spread around evenly by a sterile tool (“hockey stick”)
Spread plate
Cells are pushed onto separate areas on the surface so that they can form individual colonies
In the __ __ technique, the sample is inoculated serially into a series of cooled, but still liquid agar tubes - so as to dilute the number of cells in each successive tube in the series.
Loop dilution (or, pour plate)
Loop dilution: Inoculated tubes are poured into sterile Petri dishes and are allowed to ____
Solidify (harden)
Media whose compositions are precisely chemically defined are termed ___
Defined (PURE organic and inorganic compounds)
___ media contain at least one ingredient that is NOT chemically definable
Complex media
Extracts/cells, tissues, secretions
3 Examples of Complex media
Blood, serum, meat EXTRACTS/INFUSIONS (non synthetic)
- Nutrient broth
- Blood agar
- MacConkey agar
Media is classified according to 3 properties:
- Physical state
- Chemical composition
- Functional type (purpose)
___ is a polysaccharide - that acts as a solidifying agent in microbiological media.
agar
Agar is ___ at room temperature
Solid
Agar ___ at the boiling temperature of water (100 degrees C)
Melts (liquifies)
Once liquified, agar does not resolidify until ______
It cools to 42C
Agar can be inoculated and poured in liquid form at temperatures that will not harm the handler: ___ C - ___ C
45 C - 50 C
T/F: Isolation of colonies usually requires a large number of cells to be inoculated over an expansive area of medium
False
Requires a small # of cells to be inoculated into a relatively large volume or over a large area of medium
The ____ ____ is a property used to classify media - and referees to the medium’s normal consistency.
Physical state
Three methods of ISOLATING media
- Streak plate
- Loop dilution (pour plate)
- Spread plate
An effective microscope should provide good (3):
- Magnification
- Resolution
- Contrast
Magnification occurs in (#) phase(s)
2 (two phases)
Magnification: The lens closest to the specimen is called the ___ lens
Objective lens
Forms the INITIAL IMAGE
Magnification: The INITIAL image of the specimen is called the ___ ___
REAL image
Magnification: The image is projected up through the microscope body, the ___ ___ forms the second image.
Ocular lens (eyepiece) - the lens closest to the eye
Magnification: The SECOND image is called the ___ ___
VIRTUAL image
The total power of magnification of the final image formed by the combined lenses is a product of:
The separate power of the two lenses
10X x 10X = 1000x, 40X x 10X = 400X…
The capacity of an optical system to distinguish or SEPARATE two adjacent objects/points from one another
Resolution (resolving power)
Refers to the degree of bending that the light undergoes - as it passes from one medium to another
Refractive index
Contrast: The higher the difference in refractive indexes (bending of light), the (duller/sharper) the contrast that is registered by the microscope and eye.
Sharper
Four types of visible-light microscopes
- Bright-field
- Dark-field
- Phase-contrast
- Interference
The fluorescence microscope uses ______ as the illuminating source.
UV radiation
The confocal microscope uses ____ as the illuminating source
A laser beam
Live samples of microorganisms are placed in ______ so that they can be observed as near to their natural state as possible
Wet mounts or hanging drop mounts
The smear technique was developed by __ __
Robert Koch
____ is any procedure that applies dyes to specimens.
Staining
(Simple/Differential)staining require only a single dye
Simple staining
And and uncomplicated procedure
Differential stains use two differently colored dyes, called the ___ and the ___, to distinguish between cell types or parts.
PRIMARY dye, and the COUNTERSTAIN
Procedure in which the dye sticks to the specimen and gives it color
Positive stain
Procedure in which the dye settles some distance from the specimen’s boundary, forming a silhouette
Negative stain
2 most common dyes used for negative staining
- Nigrosin (blue-black)
2. India ink (black carbon particles)
Value(s) of negative staining
- Simplicity
- Not heat fixed (reduced shrinkage/distortion)
- Accentuates the capsule
Necessary qualities of an effective microscope
- Magnification
- Resolution
- Contrast
Differential stains are general staining techniques that use a ___ followed by a ___ to distinguish between cell types and structures.
- Primary dye
- counterstain
Characteristics of enriched mediums (3)
- May contain special growth factors
- Can use to aid in fastidious organism growth
- May contain organic substances (blood, serum, Hgb)
Place into order (largest - smallest)
- Viruses
- Protists
- Bacteria
Protists
Bacteria
Viruses
T/F: Fastidious organisms require growth factors and/or complex nutrients
True
5 types of Differential stains
2 “+” fall into more than one category
- Gram
- Acid-fast
- Endospore
- Capsule +
- Flagellar +
The name given to media which allow different types of microbes to grow - but are designed to display visible morphological, or chemical differences among those microbes is ____ media
Differential
Is the ___ plate method, some colonies will develop deep in the medium itself, and not just on the surface.
Pour plate
One can’t easily identify bacteria using only microscopic methods because bacterial cells are often so ___
Similar
Five techniques to grow, examine, and manipulate microorganisms
- Inoculation
- Incubation
- Isolation
- Inspection
- Identification
___ staining is designed to distinguish between spores stained with malachite green, and the vegetative cells from which they are produced.
Endospore
Acid-fast stain:
acid-fast bacteria color ___
non-acid-fast bacteria color ___
acid-fast bacteria - pink
non-acid-fast bacteria - blue
(Original method for M.tuberculosis in specimens)
Visualization of VIRUSES requires utilization of a ___ microscope
Electron
___ is placing a culture in a temperature-controlled chamber to encourage multiplication.
Incubation
Microbial growth in a liquid medium materializes as (4):
Cloudiness
Sediment
Scum
Color
A visible accumulation of microorganisms in or on nutrient medium
Culture
Organisms usually observed with light microscopes
Bacteria
Polysaccharide found in sea alga that is commonly used to prepare solid culture media is called:
Agar
Different types of culture ___ provide nutrients for microbial growth and can be designed to support the growth of certain microbes while inhibiting the growth of others
Media
When a culture holds two or more identified, easily differentiated species of microbes, that culture is ___
Mixed
A ____ culture resulted when a microbe of uncertain identity has been introduced into it.
Contaminated
Capsule staining is used to observe the unstructured, protective layer surrounding some ___ and ___
Bacteria, Fungi
Which unit of measurement represents the size of typical viruses?
Nanometer (nm)
____ media are important in primary isolation of a specific type of microorganism from samples containing many other species such as saliva or feces.
Selective
____ media allows multiple types of organisms to grow.
Differential
___ staining involves any staining technique in which the dye actually sticks to the specimen and gives it color, instead of staining the background.
Positive
A medium that works by showing two reaction types, such as the use/non-use of a nutrient, or color change in some colonies but not others is called a:
Differential medium
____ media are media types that have fairly gelatinous or clot like consistency which allows microbiologists to observe motility in some microorganisms
Semisolid
In ____ staining, the dye settles around the boundary of the specimen (rather than sticking to it), and forming a bright silhouette of the microbe on a dark background.
Negative
A wet mount is suitable for observing:
LIVING motile or non-motile cells
An image produced by ___ __ contrast microscopy will be vividly colored and appear 3D.
Differential interference (DIC)
The factor that out limits the clarity of a microscope’s image is the ___ ___.
Resolving power
The ___ plate technique uses a sterile tool, such as an L-shaped rod, to distribute the sample evenly around the surface of a plate.
Spread plate
A ___ culture is one that contains only ONE species or microorganisms
Pure
Defined as organic compounds that must be provided in the diet to facilitate growth (essential nutrients)?
Growth factors
The Gram stain is the most universal differential staining technique for bacteria, and it differentiates bacteria based on their:
Cell wall
The LACK OF CONTRAST in cell components - is compensated by ____ and _____
- Using special lenses (phase-contrast)
2. Adding dyes
In Gram-staining, gram-____ cells are purple, whereas gram-____ cells appear pink/red.
Purple - positive
Pink,Red - negative
Type of microscope that forms its image when light is transmitted through a specimen
Bright-field
___ ___ is used in smear preparation to simultaneously kill and secure the specimen to the glass slide.
Heat fixation
When viewing a specimen through a microscope, the ___ of view is the entire circular area that is seen through the ocular lens.
Field
Serial inoculation of a sample into separate melted agar tubes which are then poured into separate Petri dishes and allowed to solidify is a method known as __ __
Pour plating
When preparing a sample for ____ microscopy, specimens are sectioned into extremely thin slices, and stained/coated with metals to increase contrast.
Transmission electron (TEM)
The observation of live and preserved, stained specimens in a white field involves the use of ____ microscopy.
Bright-field
Phase-contrast microscopy compared to bright-field microscopy gives _____ internal detail of the cell.
A. Greater
B. Less
Greater
___ ___ microscopy is most effectively used to visualize living cells that would be distorted by drying or heat, or that cannot be stained with usual methods.
Dark-field
The ___ ___ is a measure of the amount light bends as it passes from one medium to another.
Refractive index
A ____ microscope uses a laser beam to provide 3D images of specimens that have been stained with fluorescent dye.
Confocal
The ___ image is formed when the REAL image is projected up through the microscope, to the plane of the ocular piece.
VIRTUAL image
____ media are used to determine the MOTILITY of bacteria, and to LOCALIZE A REACTION at a specific site.
Semisolid
___ staining is a general type of staining that does not disrupt the cell structure with heat fixation and can indicate the presence of a capsule.
Negative
The detection and identification of M.tuberculosis in specimens specifically requires ______ staining.
Acid-fast
____ media are media types that have a fairly gelatinous or clot like consistency which allows microbiologists to observe motility in some microorganisms.
Semisolid
The factor that most limits the clarity of a microscope’s image is the ______
Resolving power
____ microscopes are those types that use a bean of subatomic particles to allow for visualization of the specimen
Electron
Temperatures in the range of 20C-40C are used for ___ during propagation of a microbial culture
Incubation
What cell structure is designed to provide shape, support, and resistance to osmotic pressure?
Cell wall
PG
Peptidoglycan
Macromolecule that gives the cell wall of bacteria its rigid quality
Peptidoglycan
Bacteria are constantly absorbing excess water by ___
Osmosis
A ___ is an extrachromosomal piece of DNA that contains genes not essential for cell growth
Plasmid
Only gram-____ bacteria possess an outer cell membrane
Negative
Two main components of the cell envelope in most bacteria are the:
- Cell wall
2. Cell membrane
The cell (wall / membrane) primary function: a barrier between the internal and external contents of the cell
Cell MEMBRANE
The cell (wall / membrane) function: to maintain the structural strength of the cell
WALL (also cytoskeleton)
The cell wall in bacteria is primarily composed of ____
Peptidoglycan
Tiny particles composed of PROTEIN and RNA, that are the sites of protein synthesis
Ribosomes
The phospholipid barrier surrounding the peptidoglycan layer in a gram-negative bacteria is called the ___ layer
Outer
