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Strong Inference in Biology: Questioning, Experimenting, and Discovering

Explore the principles of Strong Inference in biology through questioning hypotheses, designing experiments to disprove ideas, and refining hypotheses for scientific discovery. Understand the rules of this method and its significance in scientific research.

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Strong Inference in Biology: Questioning, Experimenting, and Discovering

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  1. Dr. Stuart Reichler Bio 325

  2. Sample Exam Questions: Some organisms have much more DNA than humans do. Does this mean that they can make a greater diversity of proteins than humans can? Why or why not?

  3. Sample Exam Questions: Some organisms have much more DNA than humans do. Does this mean that they can make a greater diversity of proteins than humans can? Why or why not? Not necessarily. They may have more non-coding DNA.

  4. Sample Exam Questions: If a transposon was inserted into an intron, would the gene product still be properly produced? Why or why not?

  5. Sample Exam Questions: If a transposon was inserted into an intron, would the gene product still be properly produced? Why or why not? Either: Yes, the intron will be spliced out along with the transposon thereby having no effect on the final mRNA. No, the transposon will disrupt proper splicing of the intron thereby causing the mRNA to have additional and improper sequence.

  6. Sample Exam Questions: What is a major weakness of the data obtained via microarray analysis?

  7. Sample Exam Questions: What is a major weakness of the data obtained via microarray analysis? Microarrays show differences in mRNA levels, but that does not necessarily correlate to changes in protein levels.

  8. Start with a question. For example: How? Why? When? Where? Etc? How do we get answers? Strong Inference presents one method (article on webpage) Studying Biology:

  9. Cause of Peptic Ulcers: • Overabundance of stomach acid due to • Stress • Diet • Anxiety

  10. Cause of Peptic Ulcers: • Overabundance of stomach acid due to • Stress • Diet • Anxiety Treatment: • Antiacid U.S. bought $4.4 billion in 1992 • Tranquilizers

  11. Dr. Barry Marshall

  12. The real cause of 80% of ulcers… H. pylori

  13. The obvious or accepted answer was not the correct answer... Without alternative ideas, the answer would not have been found.

  14. Strong Inference • Knowledge is gained by eliminating incorrect ideas. • Disproof is more reliable than proof.

  15. Where does the matter come from for plants to grow? Matter can not normally be created or destroyed, only moved from one place to another.

  16. Supporting Evidence: Plants need soil to grow. If roots are removed, plants die. After several years of cultivation, soil loses its ability to support plant growth. Aristotle (~2,300 y.a.): Plants gain mass by taking it from the soil.

  17. Johann Baptista van Helmont did a simple experiment in the early 1600’s

  18. What is the major difference between these two approaches to science? Aristotle (~2,300 y.a.): Plants gain mass by taking it from the soil… Johann Baptista van Helmont in 1600’s • Supporting Evidence: • Plants need soil to grow. • If roots are removed, plants die. • After several years of cultivation, soil loses its ability to support plant growth.

  19. The Rules of Strong Inference: Strong Inference is a method for looking at scientific problems by trying to disprove hypotheses and accepting the hypotheses that can not be disproved. Using Strong Inference entails following these rules (from an article by John Platt, 1964): 1. Devise multiple hypotheses.

  20. The Rules of Strong Inference: Strong Inference is a method for looking at scientific problems by trying to disprove hypotheses and accepting the hypotheses that can not be disproved. Using Strong Inference entails following these rules (from an article by John Platt, 1964): 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses.

  21. The Rules of Strong Inference: 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses. 3. Carry out the experiments in a manner that gives a clean result.

  22. What experimental errors might this experiment have? Johann Baptista van Helmont did a simple experiment in the early 1600’s

  23. The Rules of Strong Inference: 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses. 3. Carry out the experiments in a manner that gives a clean result. 4. Repeat. Refine hypotheses.

  24. The Rules of Strong Inference: Strong Inference is a method for looking at scientific problems by trying to disprove hypotheses and accepting the hypotheses that can not be disproved. Using Strong Inference entails following these rules (from an article by John Platt, 1964): 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses. 3. Carry out the experiments in a manner that gives a clean result. 4. Repeat. Refine hypotheses.

  25. The Rules of Strong Inference: Strong Inference is a method for looking at scientific problems by trying to disprove hypotheses and accepting the hypotheses that can not be disproved. Using Strong Inference entails following these rules (from an article by John Platt, 1964): 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses. 3. Carry out the experiments in a manner that gives a clean result. 4. Repeat. Refine hypotheses.

  26. The Questions: • Can your hypothesis be disproved? • What experiment(s) can disprove your hypothesis?

  27. The Rules of Strong Inference: Strong Inference is a method for looking at scientific problems by trying to disprove hypotheses and accepting the hypotheses that can not be disproved. Using Strong Inference entails following these rules (from an article by John Platt, 1964): 1. Devise multiple hypotheses. 2. Design experiment(s) to eliminate one or more of the hypotheses. 3. Carry out the experiments in a manner that gives a clean result. 4. Repeat. Refine hypotheses.

  28. What causes Mad Cow Disease (aka BSE)?

  29. Brain tissue from cow with BSE. Scrapie in sheep, CJD or Kuru in humans looks similar.

  30. Is Mad Cow Disease (BSE) transmissible?

  31. How could you test for the infectious agent?

  32. Dr. Stanley Prusiner was awarded the Nobel Prize in 1997 for the discovery of prions… infectious proteins.

  33. normally folded proteins Interaction between prion and normal protein causes normal protein to misfold… Prion Propogation Prion (abnormally folded protein) … which leads to increasing numbers of prions

  34. Scientists communicate by publishing their findings in journals…

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