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Chapter 1: Exploring Life Slide 2 Biologists explore life from the microscopic to the global scale w Each level of biological organization has emergent properties. Biological organization is based on a hierachy of structural levels, each level building on the levels below it. Slide 3 HIERARCHY OF BIOLOGICAL ORGANIZATION w Molecules (built of many atoms to perform a function) w Organelle (conglomerate of molecules which work together to perform a process) w Cell (many organelle working together to form a living unit) w Tissue(groups of cells forming a functional unit) Slide 4 Hierarchy continued w Organ (many tissues forming a specialized center for a body function) w Organism (many organs forming functional multicellar life) w Populations: all individuals of a species living within a specific area w Communities: The entire array of organisms inhabiting a particular ecosystem w Ecosystems: Includes both biotic and abiotic factors w Biosphere: All the environments on Earth that are inhabited by life. Slide 5 Ecosystems The biosphere Organisms Populations Communities Cells Organelles Molecules Tissues Organs and organ systems Cell 1 m Atoms 10 m 50 m Slide 6 A Closer look at Ecosystems w Ecosystem Dynmaics Producers and consumers The dynamics of an ecosystem include two major processes: Cycling of nutrients, in which materials acquired by plants eventually return to the soil The flow of energy from sunlight to producers to consumers Slide 7 Energy Conversions w Activities of life require work w Work depends on sources of energy w Energy exchange between an organism and environment often involves energy transformations w In transformations, some energy is lost as heat w Energy flows through an ecosystem, usually entering as light and exiting as heat Slide 8 LE 1-4 Sunlight Ecosystem Heat Chemical energy Consumers (including animals) Producers (plants and other photosynthetic organisms) Slide 9 A Closer Look at Cells w The cell is the lowest level of organization that can perform all activities of life w The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms w Brief_History_of_Cells.asf Brief_History_of_Cells.asf Slide 10 LE 1-5 25 m Slide 11 The Cells Heritable Information w Cells contain DNA, the heritable information that directs the cells activities w DNA is the substance of genes w Genes are the units of inheritance that transmit information from parents to offspring Slide 12 w Each DNA molecule is made up of two long chains arranged in a double helix w Each link of a chain is one of four kinds of chemical building blocks called nucleotides Slide 13 Two Main Forms of Cells w Characteristics shared by all cells: Enclosed by a membrane Use DNA as genetic information w Two main forms of cells: Eukaryotic: divided into organelles; DNA in nucleus Prokaryotic: lack organelles; DNA not separated in a nucleus Slide 14 LE 1-8 Membrane Cytoplasm EUKARYOTIC CELL PROKARYOTIC CELL DNA (no nucleus) Membrane 1 m Organelles Nucleus (contains DNA) Slide 15 Concept 1.2: Biological systems are much more than the sum of their parts w A system is a combination of components that form a more complex organization w Cells, organisms, and ecosystems are some examples of biological systems Slide 16 The Emergent Properties of Systems w With each step upward in the hierarchy new properties emerge. Each level must work for the whole to work. Disrupt one part of a molecule and the organ will cease to function properly. Diabetes Slide 17 The Power and Limitations of Reductionism w In order to study an organism we break down the whole into its individual parts. w But when broken down the organism no longer functions. w Biology balances the reductionist strategy with understanding emergent properties. Slide 18 Systems Biology w Systems biology seeks to create models of the dynamic behavior of whole biological systems w An example is a systems map of interactions between proteins in a fruit fly cell w Such models may predict how a change in one part of a system will affect the rest of the system Slide 19 LE 1-10 CELL Nucleus Cytoplasm Outer membrane and cell surface Slide 20 Systems Biology w The ultimate goal of systems biology is to model the dynamic behavior of whole biological systems. Slide 21 w Systems biology uses three key research developments: High-throughput technology: methods to generate large data sets rapidly Bioinformatics: using computers and software to process and integrate large data sets Interdisciplinary research teams Slide 22 Feedback Regulation in Biological Systems w Regulatory systems ensure a dynamic balance in living systems w Chemical processes are catalyzed (accelerated) by enzymes w Many biological processes are self- regulating: the product regulates the process itself Slide 23 w In negative feedback, the accumulation of a product slows down the process itself e.g lac operon w In positive feedback (less common), the product speeds up its own production e.g. partrition Animation: Negative Feedback Animation: Negative Feedback Animation: Positive Feedback Animation: Positive Feedback Slide 24 LE 1-11 Enzyme 1 A A B B C C D D D D D D D D D D D Enzyme 2 Enzyme 3 Negative feedback Enzyme 1 Slide 25 LE 1-12 W Enzyme 4 W X X Y Y Z Z Z Z Z Z Z Z Z Z Enzyme 5 Enzyme 6 Positive feedback Enzyme 4 Enzyme 6 Enzyme 5 Z Z Z Z Z Z Z Z Z Slide 26 Grouping Species: The Basic Idea Slide 27 w Taxonomy is the branch of biology that names and classifies species into a hierarchical order w Kingdoms and domains are the broadest units of classification Slide 28 TAXONMONY: GROUPING SPECIES w 3 Domains of life Bacteria Archaea Eukarya Slide 29 BACTERIA w Contains part of the old Moneran Kingdom but now is called the Eubacteria kingdom w Most diverse and widespread prokaryotes Slide 30 ARCHAEA w Prokaryotic but live in extreme environments w Molecular evidence indicates that they have many things in common with the Eukarya. Slide 31 EUKARYA w Contains all eukaryotes w Kingdoms Fungi Protista Plantae Animalia Slide 32 LEVELS OF CLASSIFICATION w DOMAIN w KINGDOM w PHYLUM w CLASS w ORDER w FAMILY w GENUS w SPECIES Slide 33 LE 1-14 Ursidae Ursus Carnivora Mammalia Chordata Animalia Eukarya SpeciesGenus Family Order Class Phylum KingdomDomain Ursus americanus (American black bear) Slide 34 UNITY IN THE DIVERSITY OF LIFE w THE HUGE NUMBER OF SPECIES OF LIFE ON THIS PLANET GIVES US DIVERSITY w YET THERE IS MUCH THESE ORGANISMS HAVE IN COMMON. ESPECIALLY IN THE LOWER LEVELS OF ORGANIZATION EG. DNA Slide 35 LE 1-16a Cilia of windpipe cells Cilia of Paramecium 15 m 5 m Slide 36 LE 1-16b Cilia of windpipe cells Cilia of Paramecium Cross section of cilium, as viewed with an electron microscope 0.1 m Slide 37 Concept 1.4: Evolution accounts for life s unity and diversity w The history of life is a saga of a changing Earth billions of years old Slide 38 w The evolutionary view of life came into sharp focus in 1859, when Charles Darwin published On the Origin of Species by Natural Selection w Darwinism became almost synonymous with the concept of evolution Slide 39 w The Origin of Species articulated two main points: Descent with modification (the view that contemporary species arose from a succession of ancestors) Natural selection (a proposed mechanism for descent with modification) Some examples of descent with modification are unity and diversity in the orchid family Slide 40 Natural Selection w Darwin inferred natural selection by connecting two observations: Observation: Individual variation in heritable traits Observation: Overpopulation and competition Inference: Unequal reproductive success Inference: Evolutionary adaptation Slide 41 LE 1-20 Evolution of adaptations in the population Differences in reproductive success Overproduction and competition Population of organisms Hereditary variations Slide 42 w Natural selection can edit a populations heritable variations w An example is the effect of birds preying on a beetle population Slide 43 w Natural selection is often evident in adaptations of organisms to their way of life and environment w Bat wings are an example of adaptation Video: Soaring Hawk Video: Soaring Hawk Slide 44 The Tree of Life Many related organisms have similar features adapted for specific ways of life w Such kinships connect lifes unity and diversity to descent with modification w Natural selection eventually produces new species from ancestral species w Biologists often show evolutionary relationships in a treelike diagram [Videos on slide following the figure] Slide 45 LE 1-23 Large ground finch Large cactus ground finch Sharp-beaked ground finch Geospiza magnirostris Geospiza conirostris Medium ground finch Geospiza fuliginosa Small ground finch Woodpecker finch Camarhynchus psittacula Large tree finch Medium tree finch Cactus ground finch Geospiza difficilis Cactus flower eaters Geospiza scandens Seed eater Ground finches Seed eaters Tree finches Common ancestor from South American mainland Insect eaters Bud eater Warbler finches Mangrove finch Geospiza fortis Cactospiza pallida Small tree finch Camarhynchus pauper Camarhynchus parvulus Green warbler finch Gray warbler finch Certhidea olivacea Certhidea fusca Vegetarian finch Platyspiza crassirostris Cactospiza heliobates Slide 46 Video: Albatross Courtship Ritual Video: Albatross Courtship Ritual Video: Blue-footed Boobies Courtship Ritual Video: Blue-footed Boobies Courtship Ritual Video: Galapgos Islands Overview Video: Galapgos Islands Overview Video Galapgos Marine Iguana Video Galapgos Marine Iguana Video: Galapgos Sea Lion Video: Galapgos Sea Lion Video: Galapgos Tortoise Video: Galapgos Tortoise Slide 47 So.. What is life? Slide 48 So..What is life? Slide 49 THEME 10 : Science, Technology, and Society Slide 50 w Concept 1.5: Biologists use various forms of inquiry to explore life w Inquiry is a search for information and explanation, often focusing on specific questions w The process of science blends two main processes of scientific inquiry: Discovery science: describing nature Hypothesis-based science: explaining nature Slide 51 Discovery Science w Discovery science describes nature through careful observation and data analysis w Examples of discovery science: understanding cell structure expanding databases of genomes Slide 52 Types of Data w Data are recorded observations w Two types of data: Quantitative data: numerical measurements Qualitative data: recorded descriptions Slide 53 Slide 54 Induction in Discovery Science w Inductive reasoning involves generalizing based on many specific observations Slide 55 Hypothesis-Based Science w In science, inquiry usually involves proposing and testing hypotheses w Hypotheses are hypothetical explanations Slide 56 The Role of Hypotheses in Inquiry w In science, a hypothesis is a tentative answer to a well-framed question w A hypothesis is an explanation on trial, making a prediction that can be tested Slide 57 LE 1-25a Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Observations Question Slide 58 LE 1-25b Hypothesis #1: Dead batteries Hypothesis #2: Burnt-out bulb Test prediction Test falsifies hypothesis Prediction: Replacing batteries will fix problem Prediction: Replacing bulb will fix problem Test prediction Test does not falsify hypothesis Slide 59 Deduction: The Ifthen Logic of Hypothesis-Based Science w In deductive reasoning, the logic flows from the general to the specific w If a hypothesis is correct, then we can expect a particular outcome Slide 60 A Closer Look at Hypotheses in Scientific Inquiry w A scientific hypothesis must have two important qualities: It must be testable It must be falsifiable Slide 61 The Myth of the Scientific Method w The scientific method is an idealized process of inquiry w Very few scientific inquiries adhere rigidly to the textbook scientific method Slide 62 w In mimicry, a harmless species resembles a harmful species w An example of mimicry is a stinging honeybee and a nonstinging mimic, a flower fly A Case Study in Scientific Inquiry: Investigating Mimicry in Snake Populations Slide 63 LE 1-26 Flower fly (nonstinging) Honeybee (stinging) Slide 64 w This case study examines king snakes mimicry of poisonous coral snakes w The hypothesis states that mimics benefit when predators mistake them for harmful species w The mimicry hypothesis predicts that predators in noncoral snake areas will attack king snakes more frequently than will predators that live where coral snakes are present Slide 65 LE 1-27 Scarlet king snake Eastern coral snake Scarlet king snake Key Range of scarlet king snake North Carolina Range of eastern coral snake South Carolina Slide 66 Field Experiments with Artificial Snakes w To test this mimicry hypothesis, researchers made hundreds of artificial snakes: An experimental group resembling king snakes A control group resembling plain brown snakes Equal numbers of both types were placed at field sites, including areas without coral snakes After four weeks, the scientists retrieved the artificial snakes and counted bite or claw marks The data fit the predictions of the mimicry hypothesis Slide 67 LE 1-28 (a) Artificial king snake (b) Artificial brown snake that has been attacked Slide 68 In areas where coral snakes were present, most attacks were on brown artificial snakes. In areas where coral snakes were absent, most attacks were on artificial king snakes. LE 1-29 % of attacks on artificial king snakes % of attacks on brown artificial snakes Field site with artificial snakes 83% North Carolina South Carolina 17% 16% 84% Key Slide 69 Designing Controlled Experiments w Scientists do not control the experimental environment by keeping all variables constant w Researchers usually control unwanted variables by using control groups to cancel their effects Slide 70 Theories in Science w A scientific theory is much broader than a hypothesis w A scientific theory is: broad in scope general enough to generate new hypotheses supported by a large body of evidence Slide 71 Model Building in Science w Models are representations of ideas, structures, or processes w Models may range from lifelike representations to symbolic schematics Slide 72 LE 1-30 From body From lungs Right atrium Left atrium Right ventricle Left ventricle To lungs To body Slide 73 The Culture of Science w Science is an intensely social activity w Both cooperation and competition characterize scientific culture Slide 74 Science, Technology, and Society w The goal of science is to understand natural phenomena w Technology applies scientific knowledge for some specific purpose Slide 75 w Concept 1.6: A set of themes connects the concepts of biology w Biology is the science most connected to the humanities and social sciences w Underlying themes provide a framework for understanding biology Slide 76 Table 1.1 Review of Ten Unifying Themes in Biology Slide 77 Table 1.1 Review of Ten Unifying Themes in Biology (continued) Slide 78 THE END Slide 79 SCIENCE IS A PROCESS OF INQUIRY THAT ICLUDES REPEATABLE OBSERVATIONS AND TESTABLE HYPOTHESIES w DISCOVERY SCIENCE INDUCTIVE REASONING w HYPOTHETICO-DEDUCTIVE REASONING DEDUCTIVE REASONING HYPOTHESIS Slide 80 DISCOVERY SCIENCE AND INDUCTIVE REASONING w GENERALIZATION THAT SUMMARIZES MANY CONCURRENT OBSERVATIONS. E.G. ALL ORGANISMS ARE COMPOSED OF CELL BASED ON CENTURIES OF OBSERVATIONS. Slide 81 THE SCIENTIFIC METHOD AND DEDUCTIVE REASONING w HYPOTHESIS: A TESTABLE EXPLAINATION w DEDUCTIVE REASONING THE IFTHEN LOGIC Slide 82 IDEALIZED VERSION OF THE SCIENTIFIC METHOD w OBSERVE w FORMULATE QUESTION w HYPOTHESIZE w PREDICT w TEST w REPEAT Slide 83 CONTROLLED EXPERIMENT w COMPOSED OF 2 GROUPS CONTROL GROUP (STAYS THE SAME) EXPERIMENTAL GROUP CREATED BY CHANGINE 1 VARIABLE Slide 84 A THEORY w A THEORY IS A BROAD HYPOTHESIS. w IT IS BACKED UP BY EXTENSIVE AND VARIED OBSERVATIONS AND DATA. w USUALLY IT TIES TOGETHER A NUMBER OF SEEMINGLY UNRELATED OBSERVATIONS AND EXPERIMENTAL RESULTS. w E.G. NEWTONS LAWS Slide 85 SCIENCE IS A SOCIAL PROCESS w SCIENTISTS READ JOURNALS, SHARE INFORMATION AND PUBLISH THEIR FINDING FOR OTHER SCIENTISTS TO READ. w THEY CHECK AND VALIDATE PUBLISHED FINDINGS. Slide 86 TECHNOLOGY w A DEVELOPMENT THAT SOLVES A PROBLEM w NOT ALL ARE SCIENCE RELATED E.G. PRIMITIVE TOOLS w TECHNOLOGY HAS SOLVED MANY PROBLEMS BUT AT THE SAME TIME HAS CREATED OTHERS. Slide 87 Figure 1.8 Regulation by feedback mechanisms