Microscopy and Cytology

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.

4200 um 40 X X Total magnification of unknown field Total mag with scanning objective Field of view of scanning objective 4200 um 40 X X Total magnification of unknown field

4200 um 40 100 X Total magnification with low power objective 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

Calculating the field of view Objective mag Ocular mag Total mag Diameter (mm) Diameter (um) Scan 4X 10X 40X 4.2 4200 Low 100X N/A 1680 High 400X 420 Oil 1000X 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 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.

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 84-86. 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/Image: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

Rods- bacillus

Spherical-coccus

Corkscrew- spirillum

p103 Study drawing of bacterial cell Answer lab questions #2 and #3 on p 104-105.