BIOL11 - The Science of Life What are the...

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Unformatted text preview: The Science of Life What are the “Characteristics of Life” BIOLOGY n Complexity & Order Regulation n Respond to changes in environment n – Homeostasis – Physiology – Behavior – Evolution n Harness energy - metabolism Growth and reproduction n Cellular structure - “Cell Theory” n – Inheritance - DNA Organisms and their Environment Interconnect The Cell Theory 1. 2. 3. The cell is the basic unit of life. All organisms are constructed of cells. All cells derive from previous cells. Biology: Levels of Organization n Heyer Cells: the basic units of life n n Chemical Cycling Energy Flow Biology: Levels of Organization Physiological levels: n Tissues n Organs n Organ Systems 1 The Science of Life Biology: Levels of Organization n Biology: Levels of Organization Organism: the living individual Ecological levels: n Population n n Biology: Levels of Organization n Community Ecosystem Biology: Levels of Organization Biosphere: the Earth as a living system n n n n n n n n n n Molecules and Atoms Cells Tissues Organs Organ Systems Organisms Populations Communities Ecosystems Biosphere Biology: Kinds of Life Classification of Life on Earth n n Energy source – Autotrophic ( “self feeding”) — photosynthetic – Heterotrophic ( “feed on others ”) Modern five-kingdom model Cells are the basic unit of life, so define types of life by the types of their cells – Monera – Protista – Fungi – Plantae – Animalia Heyer – Prokaryote: no nucleus or other organelles – Eukaryote: nucleus & other organelles present Classical two-kingdom model – Plants – Animals n Biology: Kinds of Life Cellular characteristics for the five-kingdom model: n Organelles: specialized compartments within the cells • Intracellular digestion • Extracellular / external digestion and/or absorption • Extracellular / ingestion n Cell wall — rigid surrounding structure outside of the cell – Present or absent – Chemical structure n Tissues – Unicellular or generalized colonies – Differentiated into specialized tissue types 2 The Science of Life Monera - bacteria n n No true nucleus Small, single prokaryotic cells Protista n n single celled eukaryotic organisms i.e.: – Amoeba – algae – slime molds Two kingdoms of bacteria? Archaea & Eubacteria Plants Fungi n n Multicellular, cell wall Heterotrophic (cannot n make own food) n n i.e. yeast , mushrooms Animals (makes own food) n n Multicellular, motile Heterotrophic (cannot make own food) n Heyer i.e. worms, insects, vertebrates, “us” i.e. Trees, mosses, ferns WHAT IS SCIENCE ? n n Multicellular, cell wall, chloroplasts Photosynthesizes n n Attempts to discover the order in nature Makes predictions about what will happen Methodical process of discovery and understanding 3 The Science of Life The Scientific Method WHAT IS SCIENCE ? n n Discrimination of what is true (reality) from what only appears to be true (illusion, prejudice, & story-telling) n What is the Scientific Method? Why use this process? “Science as a way of knowing” PROCESS SCIENTISTS USE TO ANSWER PROCESS SCIENTISTS USE TO ANSWER QUESTIONS ABOUT NATURE QUESTIONS ABOUT NATURE It all starts with Observations n Careful, meticulous, well-documented observations! n Scientific n – Detailed descriptions, illustrations, maps, & anecdotes method n Why do frogs call at night? Propose plausible answers to your question. n n n n Heyer reduced predation rates reduced loss of foraging reduced water loss rates reduced phone rates Published scientific reports n – Observations – Question – Hypothesis – Prediction – Experiment Let the observations inspire specific questions! Naturalists and explorers Personal experiences – Peer-reviewed journals Proximate vs. Ultimate Questions ß Proximate questions (descriptive) ß what is it? ß how does it function? ß Ultimate questions (causal) ß why is something the way it is? ß what would be predicted about how it ß breaths ß reproduces ß is related to other organisms 4 The Science of Life The Hypothesis n n The Hypothesis Hypotheses are possible explanations of an observation. Scientists formulate hypotheses based on: 1) previous knowledge 2) inference from similar situations 3) common sense n The more basic facts you know, the better your questions. RELATIONSHIP BETWEEN RELATIONSHIP BETWEEN HYPOTHESIS AND PREDICTION HYPOTHESIS AND PREDICTION n If the hypothesis is correct.... n Then we predict the following outcome from our experiment specific prediction n Word it as falsifiable (null n n n Formulate a hypothesis) Formulate falsifiable alternative hypotheses Design tests of the prediction (experiments) Hypothesis Testing n Reproducibility: Repeated testing n n of a hypothesis precedes its tentative acceptance. Only testable hypotheses are worthwhile. Untestable hypotheses are not generally considered science. SCIENTIFIC METHOD n Hypothesis-driven science – Prediction • If … then – Test the prediction Heyer 5 The Science of Life Test the Hypotheses Test the Hypotheses n n n n Observations Questions Hypothesis/Predictions Tests (Experiments) • Control Group • Experimental Group – Standardized Variables – Independent Variable n Data/Results n Conclusion – Dependent Variable Experiments test the Hypothesis n Experiments refute or support hypotheses: n Experiments involve an – good tests can be hard and must often be clever. WHY IS IT DIFFICULT TO WHY IS IT DIFFICULT TO DRAW A CONCLUSION DRAW A CONCLUSION FROM AN EXPERIMENT FROM AN EXPERIMENT THAT IS NOT CONTROLLED? THAT IS NOT CONTROLLED? • experimental group which has variable under study experimentally altered, and a • control group which receives the same treatment as the experimental group except for the variable in question. WHY IS IT DIFFICULT TO DRAW A WHY IS IT DIFFICULT TO DRAW A CONCLUSION FROM AN EXPERIMENT CONCLUSION FROM AN EXPERIMENT THAT IS NOT CONTROLLED? THAT IS NOT CONTROLLED? n n n n n Heyer Controlled experiment has two parallel tests Experimental Control Only the “variable” is different Without control you do not know if the outcome is caused by the variable in question ? A controlled study 1. Hypothesis: Antibiotic B is better at treating ulcers than Antibiotic A. 2. Alternative Hypothesis: Antibiotic A is better at treating ulcers than Antibiotic B. 3. Null Hypothesis: treatment of ulcers is uncorrelated with Antibiotic A or B. (endoscopy) “Double-blind” controls: Neither the subjects nor the endoscopists know which subject is in which group. 6 The Science of Life A controlled study Doing Science Analysis of Results: 1) Get all background information possible (lots of it normally) 2) Collect data (often several years of work) 3) Analyze data (can take months or years) 4) Write up results & submit for peer review and publication (often >1 year until publication) 1. Correlation: Dependent variable (% effectiveness) is dependent upon independent variable (treatment group). 2. Affirmation: Hypothesis prediction supported. • Caution : correlation does not always mean causation! 3. Statistics: Groups are large enough & results are distinct enough, apparent correlation is not just coincidence. Then Æ Conclusion: Hypothesis is supported! SOME QUESTIONS ARE OUTSIDE SOME QUESTIONS ARE OUTSIDE THE REALM OF SCIENCE THE REALM OF SCIENCE n n n Heyer Hypothesis - “Ulcers are caused by negative energy waves from extraterrestrial organisms” Design an experiment....? Questions/Predictions must be testable! Scientific Theories n Widely supported explanations of broadly occurring phenomena – Cell Theory – DNA (Gene) Theory of Inheritance – Einstein's Theory of Relativity – Darwin's "theory of evolution by natural selection" n They aren’t speculation or conjecture – “Stephen King killed John Lennon - it’s true or he’d sue!” 7 ...
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This note was uploaded on 09/02/2011 for the course BIOL 11 taught by Professor Heyer during the Fall '08 term at UCSD.

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