Concept: DNA replication is possible because of the unique double helix structure and limiting connections allowed by the pyrimidine and purine base pairs. Large two-ring purines take up more space than the shorter single-ring pirimidines. Cytosine and guanine require 3 H-bonds; thymine and adenine require two. So the only possible combination pairs are AT and GC.
AP Exam preparation -- Doing the AP version of this lab:
Please read through the 2012 AP Biology Lab Manual, Investigation #3: Comparing DNA Sequences to Understand Evolutionary Relationships with BLAST. Most of the materials are online and you should be able to complete the entire lab without a problem. If for some reason you are unable to do so, you may perform one of the alternate labs below, or you may decide to perform it in addition to Investigation #3.
There was no equivalent lab in the 2002 Biology Lab Manual.
If you are unable to complete AP Investigation #3, then if at all possible, perform the Illustrated Guide to Home Biology Experiments, Lab III-5 Extracting, Isolating, and Visualizing DNA; this lab is (to my mind) even more interesting than the AP #3 lab, since it allows you to extract and view DNA yourself.
Be sure to complete and include in your final report any questions including in the lab instructions.
DNA modeling kits are available from Carolina Biological supply; but you can be as inventive as you like (I always go for edible components when possible; it is a family tradition to consume the evidence). The following is a suggestion, but whatever materials you chose, you will need 6 distinct colors and some kind of connector:
Why do you think that assembly always occurs in the 5'-3' direction?
You may wish to take photographs of your models. Identify the sequences you created and map them to an amino acid sequence.
You may consume your model, assuming you made it from edible components.
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