MadSci Network: Biochemistry

Re: What experiment would best demonstrate DNA fingerprinting techniques?

Date: Tue Jul 13 17:26:17 1999
Posted By: Sabine Heinhorst, Faculty, Chemistry and Biochemistry, The University of Southern Mississippi
Area of science: Biochemistry
ID: 927325472.Bc


Carolina Biological Supply Company ( sells a DNA 
forensics kit for $40.00 (includes DNA fragment, electrophoresis equipment 
and supplies).

Alternatively, I can think of a fingerprinting simulation activity that I 
saw at the National Museum of American History in Washington, DC last 
month. You could design a similar activity yourself. Come up with a crime 
plot featuring a set of fictitious persons (one of them is the suspect). 
You want to find out if the DNA fingerprint of one of these persons 
matches the one which was left at the crime scene by the suspect. For each 
person, make a set of “DNA fragments” that are specific for that person. 
You can make these out of mat board, strong cardboard or wood. Glue flat 
magnetic tape or small, round magnets (available in craft supply stores) 
on the bottom of one or two selected fragments for each person. Make sure 
that for two persons (suspect and one of your fictitious persons) the so 
marked fragments are identical in size and number. These magnetic 
fragments are the ones that carry the specific sequence we are looking for 
in this simulation. To find the fragments that carry the magnets (= 
specific “sequence”), use very small probe fragments that are glued to a 
magnet as described above. You will need many of these to tag all those 
DNA fragments that carry the specific “sequence”. Sort each person’s 
fragments by size from largest to smallest (= simulation of separation by 
gel electrophoresis), with fragments of the same size placed at the same 
position. Now use your probe fragments (the small ones with the magnets) 
to find those fragments that carry magnets and compare which the pattern 
of tagged fragments for each person. It should be evident which person’s 
pattern matches that of the suspect (same number and size of tagged 

Hope this is sophisticated enough.

Sabine Heinhorst

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