microscopy and quantitation of bacteria Flashcards
What are the three different types of microscope used in bacteriology?
- Bright field microscopy
- Phase contrast microscopy
- Flourescence microscopy
Define what is a bright field microscopy
It examines the detail of an microorganism by the transmitted light
It examines the detail of an microorganism by the transmitted light
Bright field microscopy
Define what is a phase contrast microscopy
It uses contrast enhancement technique allows examination of unstained specimen
It uses contrast enhancement technique allows examination of unstained specimen
Phase contrast microscopy
Define what is a fluorescence microscopy
The specimen are stained with fluorochrome or fluorescent dye
The specimen are stained with fluorochrome or fluorescent dye
Fluorescence microscopy
It is used in cleaning the objective lenses and ocular lens
Lens paper
T OR F
The mechanical stage must be on the lowest part before/after using it
True
It is used to change the objective lenses
Revolving nosepiece
T OR F
Objective lenses must be on the lowest magnification before/after using it
True
Where do we hold our hands when carrying the microscope?
Arms and Base
Minimum number in turning the rheostat when turning on the microscope
1
First objective lens to use when we are starting to focus the specimen
Scanner
What is the knob to use when using the Scanner and LPO?
Coarse Adjustment Knob
What is the knob to use when using the HPO and OIO?
Fine adjustment knob
It is added on the slide before using the OIO
Cedar wood (oil)
It is the ratio of the apparent size of an object as seen through the microscope & the actual size of the object
Magnification
The ability of the lens to clearly separate or distinguish two points of two lines individually in the image.
Resolution/Resolving Power
It is determined by the shortest wavelength of visible light & maximum numerical aperture
Resolution/Resolving Power
A measurement of the ability of the condenser and the objective lens to gather light.
Numerical Aperture
Thickness of the object that maybe seen at one time under focus.
Focal length
Distance between the front lens of the objective lens & the top of the cover glass when the specimen is in focus.
Working distance
Refers to quality of the objectives & eyepiece where practically no change in focus has to be made when objective is substituted for another
Parfocal
Bending of light rays away from the objective lens when light passes from the glass of the microscope slide to the air.
Refractive Index
Resolving power of LPO
1.34 um
Resolving power of HPO
0.52 um
Resolving power of OIO
0.26 um
What type of LENS has the higher resolving power?
a. OIO
b. LPO
c. HPO
B. LPO
Numerical aperture of LPO
0.25 NA
Numerical aperture of HPO
0.65 NA
Numerical aperture of OIO
1.30 NA
What type of LENS has the higher numerical aperture?
a. LPO
b. HPO
c. OIO
C. OIO
Magnifying power of Scanner
4x
Magnifying power of LPO
10x
Magnifying power of HPO
40x
Magnifying power of OIO
100x
What type of LENS has the higher magnifying power?
a. Scanner
b. HPO
c. OIO
d. LPO
C. OIO
What type of LENS has the lower magnifying power?
a. Scanner
b. HPO
c. OIO
d. LPO
A. Scanner
Field of view diameter of LPO
2.00 mm
Field of view diameter of HPO
0.40 mm
Field of view diameter of OIO
0.20 mm
What type of LENS has the higher field of view diameter?
a. HPO
b. OIO
c. LPO
C. LPO
Working distance of LPO
7.20 mm
Working distance of HPO
0.60 mm
Working distance of OIO
0.20 mm
What type of LENS has the higher working distance?
a. Scanner
b. HPO
c. OIO
d. LPO
D. LPO
Where do we get the formula of TOTAL magnification?
From the Eyepiece and Objective lens
Formula of Total magnification
Eyepiece x Objective
Eyepiece magnification
10x
Total magnification of eyepiece and scanner
40x
Total magnification of eyepiece and LPO
100x
Total magnification of eyepiece and HPO
400x
Total magnification of eyepiece and OIO
1000x
It refers to the ratio of the size of the image to the size of the object.
Magnification
What values do we use in computing the magnification?
The value of:
- Image size
- Actual size
Unit used for specimen size under the microscope
UNIT: Micrometers
Formula for computing magnification
Magnification = Image size (um) / Actual size (um)
1 mm is equivalent to what in micrometers (um)?
1000 um
1000 um is equivalent to what in millimeter?
1 mm
Compute for the magnification
Image size: 20 mm
Actual size: 100 um
Magnification: 20,000 um / 100um
= 200x
20 mm > 20,000 um
Formula for the microorganism size
Actual size (um): Image size / Magnification
Compute for the microorganism size:
OIO magnification: 100x
Image size measured: 1000um
Actual size: 1000 um / 100 = 10 um
