Download Unit 7 Microscopy

Microscopy and Cytology
p 73
Compound Light Microscope
• Review proper use and care of
microscope by watching video.
• Principles of microscopy p 78
A.Magnification
• Factor by which specimen is enlarged
B. Parfocal and parcentric
• Image will remain in focus and centered as
you switch from one objective to the next.
C. Size of microscopic field
• Using a ruler, you will measure the
diameter of the field using 4X scanning
objective.
• Your measurement will be somewhere
near 4.2 mm
• Ruler is in mm. Convert to micrometers
• 4200 micrometers (um)
• Formula to determine unknown field of
view if field of view of scanning objective is
known.
Total mag with
scanning
objective
40 X
Field of view of scanning
objective
X
4200 um
Total magnification of unknown field
Total mag with
scanning
objective
40
Field of view of scanning
objective
X
4200 um
100
Total magnification with low power objective
Answer: 1680 um
Calculating the field of view
Objective
mag
Ocular
mag
Total mag
Diameter
(mm)
Diameter
(um)
Scan
4X
10X
40X
4.2
4200
Low
10X
10X
100X
N/A
1680
High
40X
10X
400X
N/A
420
Oil
100X
10X
1000X N/A
168
• If the size of bacterial cells is in the range
of 1-10 micrometers, which objective
should be used for viewing bacterial cells?
D. Depth of focus
Remember to
focus on each
individual thread
to determine
which is on top.
Defined as
the vertical
distance that
an object
remains in
focus at one
time.
E. Image orientation
• View the letter E slide
If you place the slide
face up and right side
up on the stage, how
does the “e” appear
when viewed through
the microscope?
F. Resolving Power
• Degree at which 2 points on a specimen
are seen as separate images
G. Contrast
• The degree to which details of a specimen
stand out against the background
• Omit section “V. Other types of
microscopes”
Microscopy
• Answer questions on microscopy on p 8486.
• Label parts of microscope.
• You will need to know these concepts for
the lab practical.
Part II:The Cell p 89
• Review information on cellular structures
and organelles. This material will be a
review of what you have covered in
lecture.
• For the lab practical, I will only ask
questions about the structures that we
view in the lab.
Exercise 7.5 p 95
• Look over drawing and models of plant
and animal cells.
• Concentrate on identifying these
structures:
– Nucleus, nucleolus, plasma membrane,
cytoplasm, chloroplast (in plant cells), cell wall
(in plants), vacuole, cilia, flagella
Exercise 7.6 p 96
• A. Cyanobacteria-omit
• B. Elodea leaf- prepare a wet mount, view and
sketch (use a drop of water, then add safranin)
• C. Onion leaf- prepare wet mount using iodine.
Use a very thin section. Draw and label.
• D. Stained cheek cell- prepare wet mount
stained with methylene blue. Draw and label.
• E. Ear swab- omit
Cheek cells at 10X
Cheek cell at 1000X
(using 100 X oil
objective)
All photos by Jeff Beck, CCCCD unless otherwise
noted.
Onion cell
http://commons.wikimedia.org/wiki/Im
age:Microphoto-cells-onion2.jpg
Exercise 7.7 Bacterial slides p.102
• You must use OIL IMMERSION objective to view
bacteria.
• If you are not sure how to use oil, ask!
• Find the area to view using scanning, 10X and 40X
objectives, then add oil and move to 100X objective.
• Always find the area with scanning objective
first, then move to higher magnifications
• Detailed instructions for using the oil immersion objective
http://biology.clc.uc.edu/fankhauser/Labs/Microscope/Oil
_Immersion.htm
• View prepared slides of bacterial cells.
• Gram-stain
– Purple- gram positive
– Pink to red- gram negative
• Cell shapes
– Coccus
– Bacillus
– Spirillum
Rodsbacillus
Sphericalcoccus
Corkscrewspirillum
p103
• Study drawing of bacterial cell
• Answer lab questions #2 and #3 on p 104105.