Make DNA visible – Hands-On Activity

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.)

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