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MODELING
A CELLULAR OPERATION
In
this activity, you'll have the opportunity to model the removal
of a cell nucleus and the insertion of an alternate control
center. Although you won't be operating on real cells, you'll
define some of the challenges faced in this type of transplant
procedure.
OBJECTIVE
This
activity page will offer:
- a
kinesthetic experience that offers understanding in nuclear
transplants
- an
opportunity for students to emulate the removal and insertion
of a cell organelle
- an
opportunity to practice fine motor skills
MATERIALS
- commercial gelatin (clear)
- hot water (heated and distributed by instructor)
- laboratory beaker
- stirring rod
- plate
- medicine dropper
- round sugar sprinkles (used to decorate cupcakes)
- cool water
- ice water bath
- graduated cylinder
- safety goggles
- laboratory balance
PROCEDURE
PART
1 - Modeling A Cell
- Add 0.5 grams of gelatin powder to a beaker.
- Put on your safety goggles. Your instructor will add
45 mL of hot water to the powder. Carefully mix the powder.
CAUTION: Hot water can produce serious burns. Handle
with care and follow all laboratory precautions identified
by your instructor.
- Add 45 mL of cool water to the dissolved gelatin. Mix
well and place this liquid gelatin in an ice-water bath.
- After about ten minutes to fifteen minutes, examine the
consistency of the gelatin. You'll need to work with a soft,
just setting mixture. If the gelatin is too runny, leave
it in the ice-water for another 5 minutes. If its consistency
is satisfactory, remove the beaker from the ice water bath.
- Place the gelatin mound on a plate. Slice the upper half
of the gelled mass and carefully support it while scattering
several sprinkles in the center. Close up the "blob". The
sprinkles should be visible in the center of the loose gelatin.
PART
2 -Nuclear
Transplants
- Squeeze
out the air from a medicine dropper bulb.
- Poke
the delivery end of the dropper into the gelatin mass.
- Carefully
direct the opening of the dropper to the target "nucleus".
- When
the opening is in front of the nucleus, release the pressure
on the dropper bulb. What happens?
- Remove
the dropper.
- Exchange
gelatin masses with another student. Insert the "nucleus"
you removed from your gelatin into this new sample.
QUESTIONS
- What did the gelatin represent?
- What
did the round sprinkle represent?
- Why
did the bulb of the dropper need to be depressed as the
dropper was introduced into the gelatin?
CONTROVERISAL
RESEARCH
As
you might image, it's possible to insert the nucleus from
one animal into the cell body taken from another animal. This
technique forms the basis of cloning. When an animal is cloned,
the nucleus from one of its cells is inserted into the cell
body of another cell. The transplanted control center takes
over the new cell body and produces a cell with the properties
of the transplanted nucleus. As the cell divides, its daughter
cells assume the same transplanted properties. The organism
that arises from these divisions is a clone of the animal
from which the original nucleus was taken. This type of research
has the potential to produce all sorts of cloned organs that
can replace damaged human structures. Some people, believe
that this type of research is not moral and shouldn't be conducted.
What do you think? What are the advantages and disadvantages
of cloning? What common ideas about cloning are misconceptions
based upon science fiction stories? What are the real facts?
Learn
more about pig cloning and human transplants online.
WEB
CONNECTION
An
overview of nuclear transfer technology
The
background, history and ethical use of stem cells
A
well-illustrated site presenting an overview of the nucleus
The
activities in this guide were contributed by Michael DiSpezio,
a Massachusetts-based science writer and author of "Critical
Thinking Puzzles" and "Awesome Experiments in Light & Sound"
(Sterling Publishing Co., NY).
Academic Advisors for this Guide:
Corrine Lowen, Science Department, Wayland Public Schools,
Wayland, MA
Suzanne Panico, Science Department, Fenway High School, Boston,
MA
Anne E. Jones, Science Department, Wayland Middle School,
Wayland, MA
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