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