Inglemoor HS /IB Biology Year 1/Revised 2015
Activity: Cell-abration! Imaging & Sketching Cells
Investigation goals:
Which structures can we observe with the compound light microscope in wet mounts of
living cells and tissues? How big, in micrometers (μm), are these cells or their prominent cell
structures?
Your materials
Compound microscope, slides & cover slips
Cell stains (iodine, methylene blue, aceto-orcein)
Forceps, knife, dissecting needles
Specimens (see table below)
Water bottle
Sterile Q-tips
Directions:
1. Make wet mounts and sketch as many of the available specimens (see table below) as possible. Your sketches
must include cells from at least two different Kingdoms within Domain Eukarya.
2. Publish your sketches on 8.5 in. x 11 in. white paper using pencil and colored pencil for maximum information.
3. Estimate cell size (length and width in micrometers) for the sketches you make. Include the estimated cell
dimensions as part of each figure legend, along with the specimen name, magnification power, and
preparation.
Hints:
• Remember to work your way up to high power
by finding/focusing on low & medium first. In
30 min., the water on a slide dries up & the
slide must be re-made.
•
Stain a specimen (if necessary) by putting a
drop of stain on the outside edge of the cover
slip and soaking it across the specimen by
dabbing paper towel on the slip’s opposite edge. See figure to the right.
•
Use the magnification power that is best for making informative cell sketches- typically 100X or 400X.
•
Review biology specific conventions for making labeled drawings.
Table 1. Specimens
Specimen
Potato tuber
tissue
Pond water leaf
tissue
Flower petal
tissue
Red onion
epidermal tissue
24 hr baker’s
yeast culture
Cow muscle
tissue
Preparation for Viewing
Notes
Fleck off VERY thin piece. Add water. Stain with Lugol’s
iodine and look at the edge (thinnest region) of the piece.
Tear a tiny piece of leaf at an angle to obtain a “ragged”
(thin) edge. Add water. No stain.
Use a tiny piece in the wet mount. No stain needed.
Will likely be FULL of “starch grains”
or amyloplasts!
Are the chloroplasts in motion?
Take a scale from the onion, snap it backwards and
peel off the thin, red, scotch-tape like layer. No stain
needed.
Add one drop of yeast culture to your slide. Do not
add more water. Do not stain.
Tease apart a few strands of meat (muscle) & arrange on
the slide. Add a little water. Stain with aceto-orcein.
The central vacuole contains these
cells’ pigments.
You’ll “see” why they feel soft!
Yeast cells are VERY small.
You might be able to see tiny lines,
the actin and myosin proteins!
2
Human cheek
epithelial cells
Euglena
(a one-celled
pond protist)
With a sterile Q-tip, rub the inside of your cheek. Smear
the cells onto a slide; if dry, add water. Stain with
methylene blue.
Add one drop of Euglena culture to your slide. Make sure
the drop contains green culture. Do not add more water.
Do not stain.
Admire yourself!
These protists are quite complex!
Watch them swim. Look for flagella
and chloroplasts! Euglena are both
autotrophic and heterotrophic!!