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 Ratings
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| Reviewed: |
Jan 20, 2007 by Biology Editorial Board |
| Overview: |
This module on DNA Replication (Semiconservative Replication), is from the Supersite "DNA From the Beginning." It is an interactive tutorial that describes how the semiconservative model of DNA replication was verified. This learning object provides a great description of density gradient experiments used to investigate DNA replication. Research conducted by Matthew Meselson and Franklin Stahl explains how semiconservative DNA replication was confirmed. Arthur Kornbergs work on DNA polymerase is also described. This unit is organized as a set of a couple dozen concepts that delineate how scientists came to understand the fundamental ideas. This tutorial begins with a brief outline of the questions that lead to the concept, followed by a statement of the concept. A more in-depth examination of the concept is achieved through the animation menu, which accesses an animated tutorial of the basic experimental design(s) that lead to the understanding of the principle. Users may access the "Problem" menu, which presents several multiple choice questions requiring interpretation of the experimental results presented in the tutorial. The questions are instantly graded, providing immediate feedback. Additional menus are: the "Picture Gallery," with images of historical photographs of researchers, lab, and laboratory equipment used in the experiments described; the "Audio/Video" menu, that presents QuickTime interviews with researchers who discuss the concept in more detail; and a "Biography" menu, providing further information about the key scientists. A "Links" menu provides further bibliographic information, as well as links to additional relevant sites. |
| Learning Goals: |
Describe how Meselson and Stahl verified the semiconservative model of DNA replication and be able to explain how DNA polymerase was identified as the enzyme that catalyzes the replication process. |
| Target Student Population: |
Advanced high school as well as undergraduate and graduate students |
| Prerequisite Knowledge or Skills: |
No prerequisite knowledge is required, but some background in chemistry, genetics, and molecular biology may help users better understand the information. |
| Type of Material: |
Tutorial and Animation / Interactive Lesson |
| Recommended Uses: |
This material can be used in lecture or for independent study to learn about molecular genetics. |
| Technical Requirements: |
An Internet browser equipped with Flash Player and QuickTime are needed to see animations and view video clips. |
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| Strengths: |
- Accurate descriptions of the experiements by Meselson and Stahl
- Description of how Kornberg began to understand how DNA polymerase functions is very clear
- Overall site is clearly laid out, well organized, and very well presented
- Very complete and accurate information with appropriate vocabulary
- Content follows a logical progression, both conceptually and chronologically
- Animations accurately represent experimental designs presented
- Rich source of information on personalities, history,and current thought on these processes
- Exceptional combination of animation and video interviews
- The breadth of coverage is impressive and complete
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| Concerns: |
- Perhaps the titles of the units could be modified to more closely delineate the topic(s) covered.
- The site includes a good mix of video clips from scientists involved in the research. These interviews are valuable tools for learning and understanding the methods of science.
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Potential Effectiveness as a Teaching Tool |
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| Strengths: |
- Promotes understanding of the basic concepts; entire site is built around coceptual approach
- Excellent source of tutorial information
- Tutorials promote understanding of basic concepts and contain more than one approach to understanding the concept
- Tutorial animations and problems lend themselves to the creation of additional questions such as "where do we go from here?"
- Interactive quizzes provide immediate reasons for correct and incorrect answers
- Video interviews with famous scientists provide motivation for student learning
- The animations represent an excellent collection of scientific reasoning and logic, and focus on "how we know" not just "what we know." The animations frequently begin with a famous scientist posing a problem to be solved. This approach may make more of a connection between the results of a classical experiment and the mind behind the reasoning. The constant flow of scientific reasoning from unit to unit provides a clear and impressive thread of logic showing how scientists realized that DNA is the genetic material.
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| Concerns: |
- The tutorials could be improved by adding sound and expanding upon the interactivity of some of the Flash Player animations
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Ease of Use for Both Students and Faculty |
Rating:   |
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| Strengths: |
- Clear and accurate instructions
- Well designed, easy to navigate, intuitive and fast
- Widespread and effective use of animation
- Audio glossary gives detailed explanation of the term as well as pronunciation
- Definitions linked directly to the term
- Excellent use of Flash Player and QuickTime video clips
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| Concerns: |
- At the time of this review, there are a few mismatched video clips and dead links
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| Other Issues and Comments: |
The animations represent an excellent collection of scientific reasoning and logic, and focus on "how we know" not just "what we know." The animations frequently begin with a famous scientist posing a problem to be solved. This approach may make more of a connection between the results of a classical experiment and the mind behind the reasoning. The constant flow of scientific reasoning from unit to unit provides a clear and impressive thread of logic showing how scientists realized that DNA is the genetic material. The video clips of interviews with famous scientists are valuable tools for learning and understanding the methods of science. The authors might consider adding sound and expand upon the interactivity of some of the Flash Player animations. |
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