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The Case of the Druid Dracula: Clicker Case Version

Co Authors:

Norris Armstrong
Biology Department
University of Georgia

Terry Platt
Department of Biology
University of Rochester

Peggy Brickman
Department of Plant Biology
University of Georgia


This “clicker case” is a modified version of another case in our collection by the same name. It uses a PowerPoint presentation (~3MB) to present the case, which is punctuated by multiple-choice questions that students answer in class using hand-held personal response systems ("clickers"). The story revolves around a murder committed in Wales that was solved through DNA analysis. Students learn about DNA structure and replication, and how scientists have adapted this process for use in experimentation and forensic analysis, including PCR analysis and DNA fingerprinting. The students then use this knowledge to identify possible suspects in the crime. The case is designed for use in an introductory biology course either for science majors or non-majors. It could be modified for use in upper level classes as well.

  • Learn about the basic structure of DNA, including that DNA molecules are composed of two chains.
  • Understand that the two nucleotide strands in a DNA chain are complementary to each other (A-T, G-C); have distinct 5′ end and 3′ ends; and have opposite polarity (anti-parallel).
  • Learn how DNA is replicated, including: the major enzymes involved in replication and the functions of these enzymes; that during replication, each DNA strand can serve as a template for production of a new complementary DNA strand; and that scientists can mimic the mechanism to replication to copy particular pieces of DNA using the process of polymerase chain reaction (PCR).
  • Understand how DNA sequences can vary from one person to the next, including that: short-tandem repeats (STRs) are stretches of repeated nucleotide sequences that vary between chromosomes; the probability that a particular combination of STRs might exist in an individual just by chance can be estimated statistically; and scientists can identify individuals by examining these differences in DNA sequence.
Keywords: DNA; gel electrophoresis; short tandem repeats; STR; DNA replication, DNA fingerprinting; polymerase chain reaction; PCR; murder case; criminal investigation; forensic investigation; Wales
Topical Area: N/A
Educational Level: Undergraduate lower division, Undergraduate upper division
Formats: PDF, PowerPoint
Type/Method: Clicker, Interrupted
Language: English
Subject Headings: Biology (General)   Molecular Biology   Forensic Science  
Date Posted: 01/13/09
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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