Make DNA visible – Hands-On Activity – Brief Article
Stem cells contain all the genes (hereditary information) needed to give rise to any of the body’s 200 different tissue types, including skin, bone, and heart cells. Where are genes stored? Along a double-stranded molecule called DNA, which can be found inside every cell’s nucleus (center). Without DNA, stem cells would lack their incredible morphing powers.
Normally, DNA is microscopic because it’s encased inside cell, but with the right tools you can make it visible. In this experiment, you will extract real DNA from the embryos of wheat-germ grains (wheat germ comes from wheat seeds, which produce new wheat plants).
Developed by Louisa A Stark. Adapted from the Genetic Science Learning Center Web site: gslc.genetics.utah.edu
YOU NEED:
1 teaspoon (1 gram) raw wheat germ
* 1/4 teaspoon (1 milliliter) liquid detergent
* 1 tablespoon (14 ml) rubbing alcohol (70%
isopropyl alcohol) * 1 tablespoon (20 ml) hot tap
water (50 [degrees] to 60 [degrees] C) * 50 ml test tube (beaker or
spice jar will also work) * graduated cylinder *
glass or wooden stirring rod * paper clip hook *
eyedropper * paper towels
TO DO:
1. Place 1 teaspoon of raw wheat germ in a
50-ml test tube.
2. Add 20 ml of hot tap water and
mix constantly for 3 minutes.
3. Add 1/4 teaspoon of
detergent and mix gently
every minute for 5
minutes.
4. Try not to create foam,
but if you do use an
eyedropper to remove it
from the top of the
solution.
5. Tilt the test tube at a
slight angle and slowly
pour 1 tablespoon of
rubbing alcohol down
the side so that it forms a
separate layer on top of
the solution. Be careful
not to mix the two
solutions together. DNA
separates from the wheat
germ at the water-alcohol
boundary. If alcohol mixes
with water, the wheat germ
will become too diluted and
the DNA will not precipitate,
or separate from the solution.
6. Let the test tube sit for a
few minutes. White, stringy
DNA will began to appear at the
water-alcohol boundary. After about
15 minutes, the DNA will float to the
top of the alcohol layer.
7. Use a stirrer or paper clip hook to
collect the DNA.
8. Allow the DNA to air dry on a paper towel.
CONCLUSION:
How do the ingredients in this experiment work?
(For an explanation, ask your teacher. Teacher:
Please see p. TE8.)
COPYRIGHT 2001 Scholastic, Inc.
COPYRIGHT 2001 Gale Group
