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Putting the Pieces Together: The Discovery of DNA Structure and Replication
Kevin M. Bonney
This case study provides an overview of the seminal experimental work that led to the discovery of DNA structure and the confirmation of the semi-conservative model of DNA replication. By guiding students through a chronological series of historic experiments and discussing some of the collaborations and controversies involved in the original research, students learn about the history and nature of science in addition to several important biological concepts. A number of recommended videos, including one created by the author, enable instructors to use the "flipped-classroom" mode of instruction according to which students read primary literature and watch videos on their own before group discussions and activities. The case study was developed for use in an introductory undergraduate biology course, and would also be appropriate for use in a high school biology course. Some prior knowledge or instruction may be required, depending on the level and learning objectives of the course.
|Keywords:||DNA structure; DNA replication; double helix; deoxyribose nucleic acid; dispersive; conservative; semi-conservative; Photo 51; Watson and Crick; Rosalind Franklin; Meselson and Stahl|
|Topical Area:||Ethics, History of science, Women in science|
|Educational Level:||High school, Undergraduate lower division|
|Type/Method:||N/A, Debate, Demonstration, Discussion, Flipped|
|Subject Headings:||Biology (General) Genetics / Heredity|
|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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The supplemental material below can be used with this case study.Pule Chase Primer
This activity can be used in conjunction with the short film "The Double Helix" (linked to from under the Videos tab for this case). It introduces students to the classic experiment by Matthew Meselson and Franklin Stahl, which revealed that DNA replication follows the semiconservative model.
VideosThe following video(s) are recommended for use in association with this case study.
The Chemical Structure of DNA
This video uses an animation to illustrate the structure and main properties of DNA. Running time: 2:44 min. Produced by Howard Hughes Medical Institute (HHMI).
The Secret of Life—Discovery of DNA Structure
This video describes the contributions of several key scientists involved in the discovery of the structure of DNA. Running time: 8:36 min. Produced by Virginia Commonwealth University, 2014.
Building a Model of DNA Replication
This video shows a demonstration of the conservative, dispersive, and semi-conservative models of DNA replication using marshmallows and gum drops. Running time: 3:19. Created by Kevin M. Bonney for the National Center for Case Study Teaching in Science, 2015.
The Double Helix
The Double Helix is the story of the scientists and evidence involved in one of the most important scientific quests of the 20th century: the discovery of the structure of DNA. Running time: 16:53 min. Produced by HHMI BioInteractive.
DNA Replication Schematic
A 50-second animation that explains the mechanism of replication. The double helix unwinds and each strand acts as a template for the construction of the new DNA molecule. Running time 0:50 min.Produced by HHMI BioInteractive.
DNA Replication Basic Detail
Short 3-D animation showing how DNA is replicated at the molecular level. It involves an enzyme that unwinds the DNA and other enzymes that copy the two resulting strands. Running time: 1:07 min. Produced by HHMI BioInteractive.second
DNA Replication Advanced Detail
Short animation showing both strands of the DNA double helix acting as templates for the new DNA strands. Incoming DNA is unraveled by the enzyme helicase, resulting in the 3' strand and the 5' strand. The 3' strands and the 5' strands are replicated by a DNA polymerase enzyme but in different ways. Running time: 2:20 min. Produced by HHMI BioInteractive.