Extract, fingerprint, and replicate your own DNA.
By the UBC Advanced Molecular Biology Lab: Jon Nakane, Keddie Brown, Peter Danielson,
Joanne Fox, Yas Shirazu, Donna Lee, Esther Abd-Elmessih, and David Ng
W orking directly with DNA isn’t only
for the labs of CSI, agribusiness,
and headline-grabbing research
institutions. It’s basic chemistry,
but it uses the molecules of life. You can even do it
at home. This article explains how you can isolate
and “fingerprint” some of your own DNA (which is
easy), and replicate enough of it to perform more
accurate and detailed fingerprinting (which is a bit
more difficult). You can view these experiments as
an extension of high school education, a low-cost
contribution to science infrastructure in developing
countries, or perhaps even an exercise in bioethics.
First, we’ll extract some DNA from our
cheek cells, using a process similar to the
one described in Shawn Carlson’s article
on page 59 (Kitchen Counter DNA Lab),
which goes into greater detail. Here’s
how to do it.
You can find the full materials list
for this extraction method online at
1.5g (approximately ¼ tsp) table salt,
5g (about 1 tsp) of baking soda, and ½ cup bottled water.
Running buffer: .05g (a pinch) of table salt, 2g (½ tsp)
of baking soda, and up to 1L bottled water. Use a
pet-store aquarium kit to make sure this buffer measures pH 7. 5; add water to lower the pH, or add baking
soda to raise it.
1.25ml (¼ tsp) glycerol/glycerine
(available at most pharmacies) and several drops of
red food coloring.
Mix the Buffer Solutions
Mix 3 buffer solutions according to the recipes
Extract the DNA
Swirl 5ml ( 1 tsp) of rinsing buffer around in your
mouth for about 30 seconds. Swirl gently to prevent the sample from becoming frothy. The more
cells you can rinse out, the better — so don’t do this
after brushing your teeth.
Spit the buffer into a paper cup and pour it into a
test tube. Try not to spit out more (from added saliva)
than the original volume of rinsing buffer. Squirt a
bit of liquid soap (about ¼ tsp) into your sample
and mix well, but gently, with a wooden toothpick.
Slowly add 5ml ( 1 tsp) of cold rubbing alcohol to the
sample, pouring it down the side of the test tube at
an angle so you form 2 undisturbed layers of liquid.
After 10 minutes, the DNA should appear as a
whitish, snot-like substance floating between the
rinse solution layer and the alcohol. Results can