Download Cell-abrationLab

Inglemoor HS /IB Biology Year 1/Revised 2016
Activity: "Cell-abration!" Observing, Sketching & Measuring
Cells
In ves ti ga ti o n g oa l s :
o Which cellular structures and organelles can we observe with the compound light microscope?
o What are the dimensions of a typical plant or animal cell, in micrometers (µm)?
Yo ur m at eri a l s
Compound microscope, slides & cover slips
Cell stains (see table below)
Forceps, knives, dissecting needles
Specimens (see table below)
Water
Flat, sterile toothpicks
Di r ec ti o ns :
1.
Make wet mounts and sketch (pencil & colored pencil) as many of the available specimens as possible. See Table 1. Your
sketches must include cells from at least two different Kingdoms within Domain Eukarya. Your teacher will ask that everyone
in the class include a particular specimen (see step 4).
2. Each sketch is completed within a circle (representing the field of view) and the following information accompanies each
sketch:
specimen name, magnification power, and preparation (slice? whole? unstained? stained, with which one? etc.)
3. Publish your sketches on 8.5 in. x 11 in. white unlined paper.
4. Estimate cell dimensions (length and width in micrometers, µm) for your class' chosen specimen. Create a class data table
to display this information, as well as the mean and standard deviation.
Hi n ts :
•
Work your way up to high power by finding/focusing
on low & medium first. In 20 min., slides dry up &
need to be re-made.
•
Stain a wet mount (if necessary) by putting a drop of
stain to the outside edge of the cover slip and soaking
it across the specimen with paper towel. See figure 1.
•
Use the total magnification that is best for making
informative cell sketches! This is usually 100X or
400X.
Figure 1. Staining a wet mount
Table 1. Specimen Preparation
Specimen
Bananas
Pond weed leaf
tissue
Preparation for LM Viewing
Smear a little (less than the size of a sesame seed) of an
unripe (green) banana on a microscope slide. Doing this
rubs the cells apart. Add water.
Stain?
Notes
Lugol's iodine
Do you see the cells'
amyloplasts (starch plastids)?
None
Chloroplasts are green; you
might see them moving!
Red onion leaf Take a scale (leaf) from the onion, snap it backwards and peel
epidermal cells off a piece of the purple, scotch-tape like layer. Add water.
None
The reddish-purple pigments
are located within the central
vacuole.
24-48 h baker’s
yeast culture
None
Yeast cells, which are tiny,
belong to Kingdom Fungi.
Cow muscle
Tear off a tiny piece of a leaf at an angle to obtain a
“ragged” (thin) edge. Add water.
Add one drop of yeast culture to your slide. Since the
culture is already a liquid, do not add water.
You might be able to see tiny
Tease apart a few strands of meat (muscle) and arrange on
lines, like a fingerprint; these
Aceto-orcein
the slide. Add water.
are proteins in register.
Skeletal muscle is atypical,
2
with multiple nuclei per cell.
Human cheek
Paramecium
culture
With a sterile flat toothpick, gently scrape the inside of your Methylene
mouth to rub off cells. Smear them onto a slide. Add water.
blue
Add one drop of Paramecium culture to your slide. Since
the culture is already a liquid, do not add water.
None
Admire yourself!
These ciliated Kingdom
Protista cells swim rapidly!
Look for contractile vacuoles.