The Canine Caper

The Objectives:

1. To become familiar with the process of PCR 2. To conduct PCR with one DNA sample (blood from Gus, Fifi or the blanket) and simulate the steps involved in making multiple copies of the DNA fragment 3. To use PCR to isolate a specific gene and amplify it 4. To compare the PCR products (amplified DNA fragments) by simulating gel electrophoresis 5. To understand how and why gel electrophoresis separates DNA fragments based on size 6. To identify whose DNA was left on the blanket

“The Crime” Fifi was terribly nervous. She just couldn't understand why all this was happening! The park was her favorite place to visit and she could run ever so far and fast. But then that awful man was so rough with Fifi that her paw bled all over the blanket. If only her beloved owner, Tammy, would come and take her from this dark, scary place! She was certainly not accustomed to metal cages, barking dogs and the damp, dark basement.

Meanwhile at police headquarters, Mario (the Pet Detective) gets a statement from Tammy about Fifi's disappearance from the park. According to Tammy, Fifi was last seen running behind some small bushes. When Fifi did not return, Tammy searched the park in vain but with no success. At about the same time, a nearby witness, Randy the Rollerblader, reported seeing a man carrying something wrapped in a blanket. Mario knew there was only a small chance of recovering Fifi without some concrete evidence, but it would take a miracle to find any at this point.

Just hours after the dog-napping, Mario's big break arrived: Gus was picked up on an outstanding warrant and he fit Randy's description of the man with the blanket! A bloodstained blanket was found in Gus' rusty old pick-up truck; however, Gus claimed that the blood on the blanket was his own. Mario was an expert in forensic science and criminology, and recognized his opportunity to use the latest in DNA fingerprinting technology: PCR and gel electrophoresis.

You are Mario's assistant, and your mission is to use this technology to uncover whether the blood on the blanket belonged to Fifi or Gus. This information is vital, and is needed immediately for Judge O'Sullivan to issue the search warrant. Since you are new to the crime lab, Mario is going to explain how PCR works.