Summer Research Program for Science Teachers

Michelle Seeley

Elmont Memorial Junior/Senior High School

August 2005


DNA Fingerprinting through a Chemistry Lens


Aim               How does DNA Fingerprinting incorporate chemistry concepts?


Do Now           Draw an electrolytic cell used for splitting water into its elements.

                          What is necessary for this process to occur?

                          What types of charges repel?  Attract?

                          How are mixtures separated?


Equipment:             Water bath at 37°

                                Power supply

                                Hot plate with stirrer

                                Photography equipment- Polaroid.

                                Gel pouring box                  

                                20 uL micropipettors


Materials            DNA samples                                   

                              Hind III (restriction enzyme)

                              Sterile water


                             1X TAE Buffer

                             Hind lIII DNA (as size standard)

                             Carolina blu DNA Stain


                            Pipette tips

                            microfuge tubes

   (note- all DNA materials can be purchased from Bio-Rad in an easy-to-use kit.)


Methods:        Students will cut DNA with restriction enzymes. The fragments of DNA will then be separated by electrophoresis on an agarose gel. Students will see “whodunit” by analyzing the results. This lab will take 3-4 periods to run and analyze.


Overview of Time Schedule

Day 1   Review of DNA structure and function, Genetics, and basics of gel electrophoresis.  (Students take biology before chemistry, so this should be a brief review.)

Preparation of 1X.  buffer from 10XTAE solution. 

Pipetting practice.

Day 1 Lab worksheet

            Day 2    Digestion of DNA with Restriction Enzymes, pouring agarose gel

                          Day 2 Lab worksheet

Day 3    Gel Electrophoresis- Loading and Running.

              Day 3 Lab worksheet

            Day 4    Analysis of results & discussion.

                         Day 4 Lab worksheet


Pivotal ?’s:     How are stock solutions diluted? 

What type of molecule is DNA?  What type of bonding does it have, what properties?

How do restriction enzymes “cut” DNA?

                        During electrophoresis, why do the DNA fragments move?

                        What charge does DNA have?  What electrode will it travel towards?

While the DNA is traveling, bubbles are forming, explain their presence in terms of chemistry.

How can you determine the size of a DNA fragment on the basis of the distance it has moved?

                        How is gel electrophoresis particle size sorting of a mixture? 

What is a mixture that YOU could sort based on particle size?

                        What are the important chemistry concepts behind DNA profiling?


Summary      Review procedure - why is it important to understand DNA profiling?

                        How is chemistry integral to the process?

                        Who are the parents?


HW:                Complete questions on handout, and post-activity reflection.


Science Standards

Content Standard B:  All students should develop understanding of the structure and properties of matter, chemical reactions, motions and forces, and interactions of matter and energy
Content Standard E:  All students should develop abilities of technological design and understandings about science and technology
Content Standard F:  All students should develop understanding of science and technology in local, national, and global challenges