Transcript Investigating Cell Types

Investigating Cell Types
Carolina Biological Supply
25-1001
$99.95
Included in the kit:
 An order form for:
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Paramecium culture
Euglena culture
Elodea sample
8 bottles Protoslo
quieting solution
96 concavity slides
100 coverslips
Yeast packet
Congo red stain
 8 typical plant cell
slide + study cards
 8 human cheek cell
slides + study cards
 Toothpicks
 18 pipets
 16 ¼ oz jars
 8 forcepts
 Teacher’s manual and
reproducible student
guide
Needed, but not supplied:
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16 microscopes (4x, 10x, 40x)
Light source for Euglena
Liquid soap or detergent
5% salt solution (8 small containers, optional)
Small container for yeast
8 small containers of distilled water
Other supplies as deemed necessary by
students
Learning Goals
 Students will
 develop the skills necessary to design and perform
scientific investigations.
 produce testable hypotheses.
 differentiate between cell types.
 identify function of visible cell organelles as they
relate to structure.
 observe interactions between cells.
 examine structural differences between plant and
animal cells.
 investigate the effects of environmental conditions on
different cell types.
Overview
The focus is to distinguish between the
structures of plant and animal cells and to
build an understanding of why an
organism is classified as an animal, a
plant or something else.
PARAMECIUM
Paramecium is a group of single-celled eukaryotes, which are commonly
studied as a representative of the ciliate group, as they are covered with cilia
(small hairs) which allow the cells to move with a synchronous motion (like
a caterpillar) at speeds of approximately 12 body lengths per second. There is
also a deep oral groove that is used to draw food inside. They generally feed
on bacteria and other small cells. Water regulation is carried out by a pair of
contractile vacuoles, which actively expel water from the cell absorbed
by osmosis from their surroundings. Generally considered a freshwater
organism, new species have recently been discovered in the oceans.
EUGLENA
Euglena is a single-celled photosynthetic protist that can
live heterotrophically too. When acting as a heterotroph,
the Euglena surrounds a particle of food and consumes it
through phagocytosis. When acting as an autotroph, the
Euglena utilizes chloroplasts, to produce sugars by
photosynthesis. They move through the movement of a
flagella (a long whip-like tail).
ELODEA
Elodea is a genus of aquatic plants often called
the waterweeds. Elodea is native to North America and is also
widely used as aquarium vegetation. The introduction of some
species of Elodea into waterways in parts of
Europe, Australia, Africa, Asia, and New Zealand has created a
significant problem and it is now considered a noxious weed in
these areas. An older name for this genus is Anacharis, which
serves as a common name in North America.
Activity 1
 Students view prepared slides of typical
plant and animal cells.
 They also gain experience with viewing
cells under a microscope.
Procedure:
1. Students are to look at the study cards
and compare them to the prepared slides.
They will be asked to draw what they see,
looking for structures that are characteristic
of each cell type.
Activity 2
 Students view living organisms and observe
many common cell organelles.
Procedure: Paramecium/ Euglena
1. place a drop of either Paramecium culture or
Euglena culture on a clean slide without a
coverslip. Look at them under low power
and observe unimpeded movement.
2. add one drop of Protoslo to the slide. Mix
thoroughly with a clean toothpick and add a
coverslip.
3. Observe under low power and then under
high looking for cell organelles. Determine
function based on their form or shape.
4. Repeat with the other one-celled organism.
Activity 2: cont.
Procedure: Elodea
5. Remove several leaves (of varying
shades of green) from the growing tip of
the Elodea. Place one on a slide with a
drop of water and a coverslip. Examine
under low and then high power noting any
organelles seen and try to determine their
function based on shape and actions.
6. Repeat with other leaves.
Activity 3
 Students observe the organisms under a variety of
environmental conditions.
Procedure: salt
1. Students create a data table similar to the one in the
student guide.
2. Place an Elodea leaf in a salt solution for use later.
3. Add one drop of salt solution to a slide containing
Paramecium and Protoslo. Add a coverslip. Prepare
a similar salt slide with Euglena and Protoslo.
4. Look at both slides and describe any changes in the
cells.
5. Clean slides with water only and dispose of
Paramecium and Euglena down the drain.
Activity 3 : Continued
 Procedure: soap/detergent
 Follow the same procedure for all three organisms as
the salt slides but use one small drop of soap instead.
Note any changes in the cells.
 Again clean the slides with water.
 Procedure: colored yeast
 Use a toothpick to place a few colored granules of
yeast by lightly tapping the toothpick on the slide
containing the organisms and Protoslo and the
Elodea and water. Cover.
 Observe which organisms, if any, feed on the yeast.
Watch the path that takes it through the organism’s
body.
 Clean slides with water.
Activity 4
 Students design and conduct an inquiry-based
experiment of their own in order to view
additional differences between plant and animal
cells.
Procedure:
1. Design an experiment to test the similarities
and differences between different types of cells
using supplied equipment or requesting
additional items.
2. These tests will need to be repeated several
times to be sure that the results are consistent.
Suggestions for experiments
(if students need help)
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Reactions to light and/or dark
Reactions to ethanol or isopropyl alcohol
Reactions to vinegar
Reactions to heat and/or cold, or changes in
temperature
 Reactions to caffeine
 Reactions to sugar solutions
 Students should be encouraged to come up with
their own ideas and support even those ideas
that stray from the norm. A grading rubric is
included in the booklet.
Helpful hints
 Discuss cleaning and disposal. Elodea leaves
go in the garbage, Paramecium and Euglena
can go down the drain. Wash slides with only
water.
 Use Protoslo sparingly- too much can make
cells lyse. If students are having problems, have
them add the culture to a drop of Protoslo and
mix well to thicken.
 Students will probably not be able to see all the
structures on the Bioreview sheets included in
the student guide. The ones that may be visible
are boldfaced.
 If students are still having difficulty seeing
the structures because of the movement of
the organisms, one or two cotton fibers
can be added to the slide to restrict the
amount of space available.
 When students feed the organisms, stress
the importance of adding the smallest
amount of yeast possible. One tap of the
toothpick on the slide is enough. If too
much yeast is added, it will be difficult to
view the organisms.