Microscopy and Cytology

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Microscopy and Cytology

• p 73

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Compound Light Microscope

• Review proper use and care of microscope by
  watching video.
• Principles of microscopy p 78

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A.Magnification

• Factor by which specimen is enlarged

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B. Parfocal and parcentric

• Image will remain in focus and centered as you
  switch from one objective to the next.

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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)

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• Formula to determine unknown field of view if
  field of view of scanning objective is known.

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Total mag with scanning objective
Field of view of scanning objective
4200 um
40 X
X
Total magnification of unknown field
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Total mag with scanning objective
Field of view of scanning objective
4200 um
40
X
100 Total magnification with low power
objective
Answer 1680 um
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Calculating the field of view
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• If the size of bacterial cells is in the range of
  1-10 micrometers, which objective should be used
  for viewing bacterial cells?

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D. Depth of focus
Defined as the vertical distance that an object
remains in focus at one time.
Remember to focus on each individual thread to
determine which is on top.
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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?
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F. Resolving Power

• Degree at which 2 points on a specimen are seen
  as separate images

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G. Contrast

• The degree to which details of a specimen stand
  out against the background

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• Omit section V. Other types of microscopes

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Microscopy

• Answer questions on microscopy on p 84-86.
• Label parts of microscope.
• You will need to know these concepts for the lab
  practical.

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Part IIThe 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.

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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

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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

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Cheek cells at 10X
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Cheek cell at 1000X (using 100 X oil objective)
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(No Transcript)
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All photos by Jeff Beck, CCCCD unless otherwise
noted.
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Onion cell
http//commons.wikimedia.org/wiki/ImageMicrophoto
-cells-onion2.jpg
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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/Lab
  s/Microscope/Oil_Immersion.htm

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• View prepared slides of bacterial cells.
• Gram-stain
• Purple- gram positive
• Pink to red- gram negative
• Cell shapes
• Coccus
• Bacillus
• Spirillum

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Rods- bacillus
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Spherical-coccus
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Corkscrew- spirillum
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p103

• Study drawing of bacterial cell
• Answer lab questions 2 and 3 on p 104-105.