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Lecture

BIOL 112 Labs 1-12.doc


Department
Biology
Course Code
BIOL 112
Professor
Joseph Dent

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BIOL 112/Winter 2011/Lab 1 Summary
Safety in the lab
Lab coats and safety goggles with side shields should be worn in the lab at all times
No contact lenses
Material Safety Data Sheets (MSDS) available for chemicals used in lab exercises
Headings (probably don't need to know this, but just in case): product information, information
on the preparation of the MSDS, hazardous ingredients, physical data, fire and explosion hazards,
reactivity data, toxicological properties, preventive measures, first aid measures
Classes (same as the above): compressed gas, flammable and combustible material,
oxidizing material, poisonous and infectious material (divisions 1 (immediate toxic effects), 2 (other
toxic effects), and 3 (biohazardous infectious materials)), corrosive material, and dangerously reactive
material
The compound microscope
Allows us to see at the level of micrometres instead of millimetres
Microscopes are expensive instruments, so don't, say, use them as makeshift baseball bats
They aren't really suited for hitting home runs, anyway
The one we use in this lab is called the Zeiss compound microscope
Parts of a microscope:
10x eyepieces, mounted on the binocular head; differences between left and right eyepiece
can be adjusted by the dioptry adjustment collar on the left eyepiece
Body tube (where the image is formed), leading to the revolving nosepiece where the four
objective lenses are mounted:
scanning objective: 3.2x
low power objective: 10x
high power objective: 40x
oil immersion objective: 100x (requires the cover slide to be immersed in oil, with the
tip of the objective submerged in the oil as well)
Mechanical stage that holds the slide against a metal frame; the slide and the stage can be
moved using the stage movement knobs
Condenser that converges light rays coming from the light source; two lenses:

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main lens: the main lens
front (top) lens: smaller, use only for the 10x, 40x, 100x objectives; tilt it down for the
scanning objective
Condenser diaphragm: controls the amount of light that reaches condenser
Illuminator in base of microscope; intensity controlled by a knob on the base
Field diaphragm for adjusting the amount of light coming from the illuminator
It's a good idea to focus and centre on the slide using low power before switching to high power
The coarse and fine knobs should be used for the 3.2x and 10x objectives; for the higher power
objectives, use only the fine focus kob
Using the coarse focus knob with the high power objectives may cause the objective to hit and
break the coverslide lol
Total magnification formula: magnification of eyepiece x magnification of objective x
magnification of binocular tube
Oil immersion: place a small drop of oil on the coverslide, start with 40x, focus on the specimen (fine
focus only obviously)
Afterwards, wipe the objective lens with a dry Kimwipe, and the slide with a Kimwipe with a
dab of Slide Brite
Wet mounts: put some water on top of the specimen, cover with a cover slide (try to get no air
bubbles)
Can use 3.2x and/or 10x to find, then view on 40x
Examination of plant cells
Hopefully you know what cells and tissues and organs are by now so I won't go into that
Elodea leaf: first examine, then stain with iodine and examine again
Elodea: freshwater plant, important in lake ecosystems blah blah
View on 10x then 40x
May be able to view cytoplasmic streaming (chloroplasts moving around the cell)
Draw the iodine through the leaf - place a drop at one side of the coverslide, place a Kimwipe
on the other side
The iodine solution will then magically travel to the other side as if it were irresistibly attracted
to the Kimwipe or something
The iodine solution kills the leaf (lol), but you will be able to see pyrenoids (starch-containing
bodies) more clearly

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Description of drawing: cells with cell walls, a nucleus and little chloroplasts streaming around
happily within each cell
Cross sections (perpendicular to the main axis) vs. longitudinal sections (parallel to the main axis)
Selective staining: allows us to distinguish between different materials in the cells
Because different materials take up different stains etc
Lignified cell walls --> safranin (red), typical of thick-walled supportive cells
Cellulose cell walls --> fast green (guess)
Starch grains --> crystal violet (purple)
Ranunculus acris (buttercup) root: prepared slides
Drawing: an inner circle with a star-shaped gathering of lignified cells with thick red walls, and
an outer circle with a cluster of thin-walled green cells with purple starch grains (probably where the
food is kept)
Examination of animal cells
While plant cells have a thick cellulose cell wall, animal cells have no such thing
All cells have a thin plasma membrane around the cytoplasm though
Human epithelial cells, from the cheek:
Use a toothpick to put some on a slide, cover with coverslide
Stain with methyl green solution
Drawing: should look like a bunch of balls with nuclei in the middle
Small intestine of Amphiuma (cross section)
Prepared; stain is haematoxylin-eosin, nuclei are purple, cytoplasm is pink, plasma
membranes are stain-less
Drawing of cross-section: sort of like a tomato that has gone splat; villi projecting into the
lumen, that's it mostly
Drawing of epithelial cells: each has a nucleus, line the outside of the villi
Kidney tubule (nephron) of Amphiuma (cross-section)
Same stain as above, also prepared
Drawing: like hooded figures with really large hoods bordering the inside of an ellipse; those
hooded figures are the epithelial cells
These cells have nuclei which enclose nucleoli, as well as a cytoplasm
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