BIOLOGY! What is LIFE? The Study of Life. What are the Properties of Life? bios = life ology = study of

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1 BIOLOGY! The Study of Life bios = life ology = study of What is LIFE? I know it when I see it! What are some characteristics we associate with the definition life? What are the Properties of Life? 1. Precise organization (order) 2. Homeostasis 3. Response to the environment 4. Energy uptake and use 5. Growth and development 6. Reproduction 7. Ability to Evolve 1

2 Properties of Life 1) Order Properties of Life 2) Homeostasis Properties of Life 3) Response to the Environment 2

3 Properties of Life 4) Energy Processing Properties of Life 5) Growth and Development Properties of Life 6) Reproduction 3

4 Properties of Life 7) Evolution & Adaptation Properties of Life? 1. Precise organization (order) 2. Homeostasis 3. Response to the environment 4. Energy uptake and use 5. Growth and development 6. Reproduction 7. Ability to Evolve Is It Alive? Why or Why Not? Cologne Cathedral Baby Chicken Escherichia coli bacteria Hoover Dam 4

5 Levels of Organization: Biosphere Ecosystems Populations Individuals Communities Organs or Organ Systems Levels of Organization: Organs or Organ Systems Organelles Tissues Cells Molecules Emergent Properties Each level of the biological hierarchy is more than merely the sum of its parts Emergent properties result from interactions among components at each level 5

6 Emergent Properties. Life itself is an emergent property Cells are the simplest units of life. The cell is the lowest level of structure that has all of the properties or qualities we use to define life. Some organisms consist of a single cell, others are multicellular aggregates of specialized cells. The first cells were observed and named by Robert Hooke in 1665 from a slice of cork. Hooke s Compound Microscope Observation XVIII" of the Micrographia 6

7 Anton van Leeuwenhoek, was the first to see single-celled organisms in pond water and observe cells in blood and sperm. Anton van Leewenhoek No more pleasant site has met my eye than this! Van Leewenhoek`s simple microscope Leeuwenhoek reported how in the plaque scraped from his teeth: "I then most always saw, with great wonder, that in the said matter there were many very little living animalcules, very prettily a-moving. The biggest sort... had a very strong and swift motion, and shot through the spittle like a pike does through the water." In the mouth an old man who had reportedly never cleaned his teeth in his life: "an unbelievably great company of living animalcules, a-swimming more nimbly than any I had ever seen up to this time. THE CELL THEORY In 1839, Matthais Schleiden and Theodor Schwann extrapolated from their own microscopic research and that of others to propose the cell theory. The cell theory postulates that cells are the basic unit of structure and physiology in all living things. One of the great paradigms of Biology Cell Theory is to Biology as the Atomic Theory is to Physics But... Thought cells formed spontaneously in a manner similar to crystal growth In 1855, Rudolf Virchow extended the cell theory : New cells are produced by the division of existing cells. Critical process in reproduction, growth, and repair of multicellular organisms. 7

8 All cells are enclosed by a membrane that regulates the passage of materials between the cell and its surroundings. All cells contain DNA, the heritable material that directs the cell s s activities. Two major kinds of cells - prokaryotic cells and eukaryotic cells - can be distinguished by their structural organization. The cells of the microorganisms called bacteria and archaea are prokaryotic. Do not contain organelles. All other forms of life have the more complex eukaryotic cells. The continuity of life is based on heritable information in the form of DNA Biological instructions for life are encoded in DNA (deoxyribonucleic( acid). DNA is the substance of genes. Genomes (Human and Others) The entire library of genetic instructions that an organism inherits is called its genome. The genome of a human cell is 3 billion chemical letters long. The rough draft of the sequence of nucleotides in the human genome was published in Biologists are learning the functions of thousands of genes and how their activities are coordinated in the development of an organism. 8

9 Unity & Diversity Diversity: 1.5 million species described third million plant species vertebrates almost 1 million insects Estimates 5-30 million species (10% described?) Diversity decreasing as species go extinct. Unity & Diversity Taxonomy: classifying and organizing life 7) Unity & Diversity Taxonomy: classifying and organizing life species Genus Family Order Class Phylum Kingdom Spaghetti Good For Over Came Phillip King 9

10 Examples from the Animal Kingdom ORGANISM GROUP NAME HUMAN CHIMPANZEE HOUSE CAT LION HOUSEFLY KINGDOM Animalia Animalia Animalia Animalia Animalia PHYLUM Chordate Chordate Chordate Chordate Arthropoda CLASS Mammal Mammal Mammal Mammal Insect ORDER Primates Primates Carnivora Carnivora Diptera FAMILY Hominidae Pongidae Felidae Felidae Muscidae GENUS Homo Pan Felis Panthera Musca SPECIES sapiens troglodytes domestica leo domestica Scientific Name Homo sapiens Pan troglodytes Felis domestica Felis leo Musca domestica Unity & Diversity DOMAINS 1. Bacteria 2. Archea 3. Eukarya 1. Plantae 2. Animalia 3. Fungi 4. Protista = Monera Unity & Diversity 5 Kingdoms 1. Monera = Bacteria 2. Plantae = Plants 3. Animalia = Animals 4. Fungi = Fungi 5. Protista = Protists 10

11 Unity & Diversity Unity within diversity: DNA as the common information molecule Eukaryotes all share common cellular architecture The Nature of Science (& the scientific method) Science is a process of inquiry that includes repeatable observations and testable hypotheses. A) Discovery Science (Induction) Observations Data collection In field or lab! B) Hypotheticodeductive model Scientific method Formal process Experimentation In field or lab! How weird!... some of the frogs in this pond have 3 back legs! What the heck is going on here!?!? Puzzling observation Causal question 11

12 Causal Questions: Ask what is CAUSING a particular phenomenon or observation. What causes frog deformities? CAUSATION is very different from CORRELATION Causal question: What is causing these frog deformities? Possible explanations (hypotheses): Polluted water (e.g. herbicide runoff from fields) Infection by parasites Increased UV radiation CAUSATION does not equal CORRELATION Not all explanations are hypotheses Elves cast a spell on the frogs. God made them that way. A possible explanation about what CAUSES something is a: HYPOTHESIS! Pollution is causes leg deformities in leopard frogs. Prediction: IF frog deformities are caused by polluted water, THEN there should be more deformities in frogs raised experimentally in polluted water vs. those experimentally raised in clean water. 12

13 IF the hypothesis is TRUE, THEN we can predict an outcome. Hypothesis Test Data: % deformed frogs in atrazine water = 0 % deformed frogs in pure water= 0 Compare! Predicted Outcome from a planned experiment Actual Experiment Causal Question: Question about how or why things occur. Hypothesis: A testable explanation, a possible answer to a causal question Prediction: An expectation (derived from the hypothesis) about what you SHOULD see, if you were to do an experiment or make more observations. Test: Evidence (data) derived from an actual experiment or observation that can be matched against predicted result. Conclusion: A decision about whether or not the evidence supports the hypothesis. Causal Question Science is a Cycle: Hypothesis Conclusion Prediction Test (data) 13

14 Label each statement: Causal question, hypothesis, prediction, test/data, and conclusion. 1. Trematode infection is probably responsible for frog deformities 1. Conclusion 2. What makes tadpoles produce frogs with extra legs? 2. Causal 3. The proportion of adult frogs with deformities should increase Question with increasing exposure to parasitic infections 3. Prediction 4. I wonder if infection by trematodes could disrupt tadpole 4. Hypothesis development? 5. Test 5. Density of trematodes (per tad) % of frogs w/ limb deformities New Hypothesis: Abnormal development of frogs is caused by a trematode parasite Steps of the Scientific Method 1) Observation The flashlight doesn t t work! 2) Ask Questions (Collect Information) (a) Why doesn t t the flashlight work? (b) How does a flashlight work? 3) Form a hypothesis (Educated Guess) The batteries are dead! 4) Experimentation:Test of hypothesis Replace the batteries. 5) Collect results & Draw a conclusion (a) It works hypothesis supported (b) It doesn t t work hypothesis rejected (go to step 3) 14

15 A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations In mimicry A harmless species resembles a harmful species Field Experiments with Mimicry. In this study: Mimicry in king snakes is examined The hypothesis predicts that predators in non coral snake areas will attack king snakes more frequently than will predators that live where coralsnakes are present South Carolina North Carolina Key Kingsnake Coralsnake Eastern Coral snakes are lethal to most predators so. Field Experiments with Artificial Snakes To test the mimicry hypothesis Researchers made hundreds of artificial snakes, an experimental group: resembled king snakes control group: of plain brown snakes (a) Artificial king snake (b) Brown artificial snake that has been attacked 15

16 After four weeks the researchers collected the model snakes (the data!) Key % attacks on kingsnakes % of attacks on brown snakes Field sites And in this case the data on incidence of predation fit a key prediction.. Coralsnakes absent: most attacks on kingsnake models X X X X X 83% X X X X XX 17% X X X 16% Coralsnakes present: most attacks on brown models 84% Limitations of the Scientific Method Remember: Science seeks natural causes for natural phenomena. The scope of science is limited to the study of structures and processes that we can observe and measure,, either directly or indirectly. Verifiable observations and measurements are part of science. Results are repeatable. (Scientists publish their findings, so other scientists can verify them) EVOLUTION Came into sharp focus in 1859 when Charles Darwin published On the Origin of Species by Natural Selection 16

17 Darwin proposed natural selection As the mechanism for evolutionary adaptation of populations to their environments Population of organisms Hereditary variations Overproduction and struggle for existence Differences in reproductive success Evolution of adaptations in the population Natural selection- is one of the mechanisms by which evolution occurs 1 Populations with varied inherited traits When a population s heritable variations are exposed to environmental factors that favor the reproductive success of some individuals over others 2 Elimination of individuals with certain traits. 3 Reproduction of survivors. 4 Increasing frequency of traits that enhance survival and reproductive success. 17