Bio 10- Fundamentals of Biology

Transcription

1 Bio 10- Fundamentals of Biology Lab schedule : Contact your instructor at: biologyatelcamino@gmail.com K. Villatoro Grade breakdown Lab tests 29% Labs work 11% Lecture 60% 1

2 How to succeed in this lab? - Successful students focus on the work to be done. spend appropriate amounts of time studying. - Successful students study for comprehension. aim to understand course content rather than simply complete requirements. - Successful students get involved. Ask questions, form study groups, and use the resources that the college and course offers to help learn. Concept Mapping: enhances comprehension Organizes concepts to show relationships Helps you retain information 2

3 Structural Map Sandwiches Outside components Fillings Bread Tortillas Veggies Cheeses Meats 3

4 Process Map PART 1: Practice constructing concept maps Structural map And Process map 4

5 What do we know about the world around us? How do we know these things? Are we certain these things are accurate? Has anyone discovered that something we knew, turned out to be wrong? What does SCIENCE have to do with the WORLD around us? Science is both a body of knowledge of the world and the process of learning about it Tools of science What do you think is the cause of the car s problem? Why wouldn t a mechanic think it is a demon? 5

6 Science has limits FIRST: it can only study natural world Can either be perceived directly by our senses SECOND: or indirectly by using instruments it can ONLY look for NATURAL explanations In pairs Sunsets, souls and senses Discuss which items can be investigated by science and which items can not Fill out handout Does science deny the existence of god? 6

7 How is science done? Science may use experiments to test ideas An experiment should: -Compare outcomes -Control variables -Avoid bias -Distinguish chance from real differences 7

8 What about past events? Like a crime scene Can science study them? Science collects evidence of unseen events and reach conclusions without any experimentation What happens after a test is done? 8

9 Part 3. An End to Ulcers? A case of how science is done? or was done! 17 CQ1: What do you think causes ulcers? A: Stress. B: Excessive stomach acids. C: Bacteria. D: A bad diet and alcohol use. E: Being overweight. 18 9

10 History of the understanding of stomach function & ailments HIPPOCRATES WILLIAM BEAUMONT 19 CQ2: Which is a good way to test the excess acid hypothesis? A: Examine ulcer patients of a range of ages and measure their stomach acid levels. B: Have volunteers drink alcohol and measure their stomach acid levels. C: Lower stomach acid levels of some volunteers (using drugs/antacids), and measure numbers of ulcers in all volunteers. D: Examine patients of a range of ages and measure the number of ulcers in each person. E: Put volunteers through a stress test and then measure their stomach acid levels

11 # Ulcers/ patient A Possible Study Design Doctors divide patients into two groups: Group 1 received antacids and were instructed to take them 3x/day Group 2 received sugar pills and were instructed to take them 3x/day After 3 months, the number of ulcers per patient is assessed. Predict what the results would look like if the excess acid idea was supported. 21 Draw this graph: Predict what the results would look like if the excess acid hypothesis was supported by the results of this study: Group 1 Group 2 Treatment Group 22 11

12 # Ulcers/ patient # Ulcers/ patient # Ulcers/ patient # Ulcers/ patient CQ3: Which graph most closely matches the results you predicted? A B C Group 1 Group 2 Treatment Group D Group 1 Group 2 Treatment Group Group 1 Group 2 Treatment Group Group 1 Group 2 Treatment Group 23 Unfortunately, this type of controlled experiment was NOT conducted. BUT, patients who took antacids had decreased ulcer symptoms. If the patients stopped taking the antacids their ulcers returned

13 Dr. J. Robin Warren: (pathologist) Examines stomach biopsies of patients with various stomach ailments. 25 CQ4: The slides that Dr. Warren examined had smudges that were not clearly visible under low power, so he attached a high-power lens to his microscope. What do you think he was able to see then? A: Many cells at once. B: Only one cell at a time. C: Organelles within the cells. D: Bacteria. E: Viruses. LOW POWER 26 13

14 Dr. Warren thought he saw: Helicobacter pylori (a new species of bacteria) But no one else believed him! The black squiggly spots on the slide are bacteria that Dr. Warren observed In his biopsy slides. 27 CQ5: Dr. Warren s colleagues did not believe there were bacteria in the stomach. Why do you think other pathologists did not believe bacteria were in the stomach biopsies? A: Bacteria are never found inside the human body. B: The ph of the stomach is too acidic for any bacteria to survive. C: No one else had reported seeing bacteria in their biopsy samples. D: Ulcers and stomach cancer are caused by age, stress and diet bacteria have nothing to do with the problems the patients came to the hospital for

15 Used a special stain that highlights bacteria on his slides. This convinced his colleagues that the bacteria were there. So, Dr. Warren: 29 Talk to your neighbor Dr. Warren thinks H. pylori causes ulcers. What is another hypothesis to explain why Dr. Warren was finding bacteria on his slides? (there are at least three alternative hypotheses...) 30 15

16 Alternative explanations (hypotheses): 1. The biopsy specimens were contaminated AFTER samples were taken from the patients. 2. The bacteria live in the stomach, but do no damage. 3. The bacteria are an opportunistic species that arrives AFTER ulcers have already weakened the stomach s defenses. 31 Dr. Barry J. Marshall Joins Dr. Warren s Research Hypothesis: Bacteria CAUSE stomach ulcers. If you were working with Drs. Warren & Marshall to design a study to determine whether the bacteria caused ulcers, how would you do it? 32 16

17 Their First Survey Study: 100 stomach ulcer patients surveyed (biopsy taken). 100% had H. pylori present. 33 CQ6: The doctors treated ulcer patients with antibiotics to see if the disease stopped. What is missing from their study? A: An experimental treatment. B: A control group. C: An independent variable. D: A dependent variable. E: A hypothesis

18 Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months If they set up their antibiotic study with a treatment group receiving antibiotics and a control group receiving a placebo (no antibiotics), what results would you expect if the original excess acid hypothesis was supported? Control Experimental 35 CQ7: What results would you expect if the old excess acid hypothesis were supported? A B Con Exptl Con Exptl C D Con Exptl Con Exptl 36 18

19 Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months Number of ulcers after 2 months What results would you expect if Drs. Warren and Marshall s bacteria cause ulcers hypothesis is supported? Control Experimental 37 CQ9: What results would you expect if the bacteria cause ulcers hypothesis were supported? A B Con Exptl Con Exptl C A D Con Exptl Con Exptl 38 19

20 Actual Results of Warren & Marshall s Study When treated with antibiotics, 80% of patients were permanently cured of their ulcers. To further demonstrate the cause and effect relationship, Dr. Marshall (who did NOT suffer from ulcers), swallowed a flask of H. pylori from the lab. Within a week he was suffering from symptoms of gastritis and had H. pylori populations in his stomach! He cured himself with an antibiotic treatment. 39 CQ9: If you were shown the results of the Warren & Marshall antibiotic study, you would conclude: A: The excess acid hypothesis is supported and is the best explanation for the causation of ulcers. B: The bacteria cause ulcers hypothesis is supported and is the best explanation for the causation of ulcers. C: The excess acid hypothesis has not been overturned, but bacteria might have something to do with ulcers. D: This study supports the bacteria cause ulcers hypothesis, but I need more evidence

21 Medical doctors worldwide were NOT easily convinced Drs. Warren and Marshall had trouble getting their results published in scientific journals and presenting results at scientific meetings. It took over 15 years and many more studies from researchers all over the world, before the bacteria cause ulcers hypothesis was accepted by the medical community. 41 Drs. Warren & Marshall win the 2005 Nobel Prize in Medicine & Physiology 42 21

22 CQ10: If your father was diagnosed with stomach ulcers, what do you think the recommended treatment would be today? A: Lower stress levels. B: Change diet to eliminate spicy food. C: Take a course of antibiotics. D: Drink milk to lower stomach acid levels. E: Lose weight and exercise. 43 What Science is? What Science is not? Limited to the Natural world (natural phenomena with natural causes) Observable Testable Measurable Repeatable Modifiable Open to change (based on events perceived by our senses) (ideas must be able generate expectations ) (quantifiable) (by different people with similar results) (not fixed for all time, not based on dogma) (new evidence can modify or replace concepts) Strong theories inferred from solid evidence (not just a list of facts, but explanations of observations) Made stronger by different lines of evidence (independent unrelated fields of study point to same explanation) A search for understanding (how the universe works why it is that way it is) 22

23 Proves or disproves ideas (proof = finality and certainty, science accepts or rejects ideas) Based on belief or faith (not based on feelings but objective evidence) Based on authority (experts can be in error) A search for truth (truth can mean different things to different people) Fair Democratic (whatever is, is) (there is no voting in science, not based on popularity but evidence) Able to solve all problems (limited to the natural world) A collection of facts 23