involved a number of important historical experiments. These include:
i. Contributions of Watson, Crick, Wilkins, and Franklin on the structure of DNA
ii. Avery-MacLeod-McCarty experiments
iii. Hershey-Chase experiment
How can DNA, a submicroscopic molecule, be visualized with the naked eye?
What must be done to extract and isolate DNA from human cheek cells?
What can we conclude about the chemical nature of DNA through isolation techniques?
1. Obtain a 15 mL test tube and label it with your name.
2. Obtain a small cup of sports drink and swish it around in mouth for one full minute. While swishing, you should gently and continuously scrape the sides of your cheek with your molars.
3. Spit the drink (with the collected cheek cells) back into the small cup.
4. Pour the contents of the cup into the labeled test tube (discard the cup).
5. Holding the test tube at an angle, they will use the provided plastic pipette to add 2mL of detergent solution to the collected cheek cells.
6. Cap the test tube, and invert it five to eight times.
7. Allow this to stand for two minutes.
8. Using the provided pipette, add the cold alcohol by letting it run gently down the side of the test tube (holding the test tube at an angle). Add the alcohol until the total volume reaches 12–13mL. You should have two distinct layers. Do NOT mix the cheek cell solution with the alcohol!
9. Observe as strands of a translucent solid begin to precipitate where the alcohol layer meets the cheek cell solution.
10. Place the 15mL test tube in a test tube rack and let it stand undisturbed for 15 minutes. During this time the solid will continue to precipitate out.
11. Use a plastic pipette to transfer the solid DNA into a smaller test tube. To do so, place the pipette near the DNA and draw the DNA into the pipette (along with some alcohol). You should NOT move the pipette up and down into the bottom layer.
It is impossible, of course, to list all of the useful DNA-related websites, but here are a few of the most comprehensive. We also list below a few sites that relate the study of DNA and genetics to other areas of the curriculum. Each of these sites has extensive links to educational resources.
The National Center for Biotechnology Information Home Page
This is a comprehensive website with access to GenBank, free literature, molecular databases,
and genome resources for multiple species. Multiple free textbooks can be accessed and
simultaneously searched through this site.
Human Genome Project Websites
The RCSB Protein Data Bank
The worldwide repository for the processing and distribution of 3-D biological macromolecular
This is a very large collection of bioinformatics, genomics, proteomics, biotechnology, and
molecular biology links.
The People of Genetics
Dolan DNA Learning Center, Cold Spring Harbor Laboratory
DNA Interactive, from the Dolan DNA Learning Center