生物学简介英文版.ppt

2-,Introduction to Biology,1-,Why a Study of Biology is Important?,SocietalMedicinePublic Health Worldwide Water Crisis,1-,Why a Study of Biology is Important?,PhilosophicalEvolutionGenetics,1-,1-,1-,Why a Study of Biology is Important?,PersonalTo be informedSupport your causeMake it your life work,1-,bahy-ol-uh-jee,Bio=life.ology=the study ofBiology is the science that studies life,1-,The Scientific Method in Action,A systematic way of gaining information,1-,The Scientific Method:Observation,An observation is a thoughtful and careful recognition of an event or a fact.The careful observation of a phenomenon leads to a question.How does this happen?What causes it to occur?,1-,The Scientific Method:The Hypothesis,Hypothesizing question an observationpropose possible solutions to questions based on what is already understood about the phenomenon Hypotheses must:be logicalaccount for all current informationmake the least possible assumptionsbe testable,1-,Testing Hypotheses,Hypotheses need to be tested to see if they are supported or disproved.Disproved hypotheses are rejectedHypotheses can be supported but not provenWays to test a hypothesis:Gathering relevant historical informationRetrospective StudiesMake additional observations from the natural worldExperimentation,1-,The Scientific Method:Experimentation,Experimentsrigorous tests to determine if the solutions are supportedExperiments attempt to recreation an occurrencetests whether or not the hypothesis can be supported or rejectedThere are many types of experimentslaboratory,clinical trials,surveys,statistical analyses,1-,Experimental Design,All experiments have key elements in common:Experiments must be controlledthis means that all aspects except for one variable must be kept constantusually include any two groups.Experimental group:variable is altered,independent variable Control group:variable is not altered,dependent variableExperiments use models to recreate occurrences,but in a controlled settingmodel organisms,ISS,cohorts,1-,Experimental Design,Experiments must:use large numbers of subjects and/or must be repeated several times(replication)be independently reproducibleThe validity of experimental results must:be tested statisticallychi-squared test for statistical significancebe scrutinized by other scientistspeer reviewed,1-,Theory,If the hypothesis is supported by ample experimental data,it leads to a theory.A theory may be defined as a widely accepted,plausible general statement about a fundamental concept in science.The germ theory states that infectious diseases are caused by microorganisms.Many diseases are not caused by microorganisms,so we must be careful not to generalize theories too broadly.Theories continue to be testedExceptions identifiedModifications made,1-,A Scientific Law,A scientific law is a uniform and constant fact of nature that describes what happens in nature.An example:All living things come from pre-existing living things.Scientific laws promote the process of generalization.Inductive reasoningSince every bird that has been studied lays eggs,we can generalize that all birds lay eggs.Once a theory becomes established,it can be used to predict specific facts.Deductive reasoningWe can predict that a newly discovered bird species will lay eggs.,1-,Scientific Communication,Data is shared with the scientific community through research articles published in scientific journals.peer reviewScientists present preliminary data at conferences.Scientists collaborate directly by phone and e-mail.,1-,A Sample Experiment,Scientific American August 2010,1-,A Sample Experiment,Article:Hardt,Marah J.and Safina,Carl.“Threatening Ocean Life from the Inside Out.”Scientific American August 2010:Vol.303 2.What types of observations were being made?State a hypothesis that was tested.Describe an experiment that was conducted.Discuss a variable that was studied and describe how constants where maintained in the experiment.How was a model system was used to simulate the conditions being studied.How were the complex processes being studied reduced to their simplest parts?What was learned from the experiments?,20,The Science of Biology,Chapter 1,21,1.1 The Science of Life,Biology unifies much of natural lifeBiology attempts to define lifeBiology Living reveals a hierarchical organization of living systems,2,22,Properties of Life,Living organisms:are composed of cells(Cellular Organization)are complex and ordered(Ordered Complexity)respond to their environment(Sensitivity)can Grow,Develop and Reproduceobtain and use energy(Energy Utilization)maintain internal balance(Homeostasis)allow for Evolutionary Adaptation The definitions of life are adapting with the fieldwhere do viruses fit in?,23,Levels of Organization,Cellular Level Atoms molecules organelles cells Organismal LevelTissues organs organ systems Population LevelPopulation species biological community Ecosystem LevelBiological community+physical habitat(soil,water,atmosphere)The BiosphereThe entire planet thought of as an ecosystem,4,24,Levels of Organization,Cellular Organization cells organellesmolecules atomsThe cell is the basic unit of life.,Fig.1.1-1,6,26,Levels of Organization,Organismal Level organism organ systems organstissues,Fig.1.1-2,8,28,Levels of Organization,Population Level ecosystem community speciespopulation,Fig.1.1-3,10,30,Levels of Organization,Each level of organization builds on the level below it but often demonstrates new features Emergent properties:new properties present at one level that are not seen in the previous level New properties emerging may be greater than the sum of the the parts,31,1.2 The Nature of Science,Science aims to understand the natural world through observation and reasoning Science begins with observations,therefore,much of science is purely descriptive Science uses both deductive and inductive reasoning,32,The Nature of Science,Deductive reasoning uses general principles to make specific predictions.Inductive reasoning uses specific observations to develop general conclusions.,33,The Nature of Science,Scientists use a systematic approach to gain understanding of the natural world:ObservationHypothesis formationPredictionExperimentationConclusion,34,The Nature of Science,A hypothesis is a possible explanation for an observation.A hypothesis:must be tested to determine its validity is often tested in many different ways allows for predictions to be made,35,The Nature of Science,The experiment:tests the hypothesis must be carefully designed to test only one variable at a time consists of a test experiment and a control experiment,36,The Nature of Science,If the hypothesis is valid,the scientist can predict the result of the experiment Conducting the experiment to determine if it yields the predicted result is one way to test the validity of the experiment,37,Think Like a Scientist,38,The Nature of Science,Scientists may use:reductionism-to break a complex process down to its simpler parts models to simulate phenomena that are difficult to study directly,39,Test the early hypothesis of Spontaneous Generation,Fig.1.4,40,The Nature of Science,A scientific theory:is a body of interconnected concepts is supported by much experimental evidence and scientific reasoning expresses ideas of which we are most certain,41,1.3 An Example of Scientific Inquiry:Darwin and Evolution,Charles Darwin served as naturalist on mapping expedition around coastal South America.Used many observations to develop his ideas Proposed that evolution occurs by natural selection,42,Voyage of the Beagle,43,Charles Darwin,Evolution:Modification of a species over generations“descent with modification”Natural Selection:Individuals with superior physical or behavioral characteristics are more likely to survive and reproduce than those without such characteristics,44,Darwins Evidence,Similarity of related species Darwin noticed variations in related species living in different locations,45,Unnatural Selection,46,Darwins Evidence,Thomas Malthus:Population growth vs.availability of resources-population growth is geometric-increase in foodsupply is arithmetic,47,Darwins Evidence,Population growth vs.availability of resources Darwin realized that not all members of a population survive and reproduce Deduced that the organisms best adapted to obtaining resources would survive to reproduce Darwin based these ideas on the writings of Thomas Malthus,48,Post-Darwin Evolution Evidence,Fossil record Intermediate OrganismsMechanisms of heredity-Early criticism of Darwins ideas were resolved by Mendels theories for genetic inheritance,49,Post-Darwin Evolution Evidence,Comparative anatomy-Homologous structures have same evolutionary origin,but different structure and function.-Analogous structures have similar structure and function,but different evolutionary origin.,50,Homologous Structures,51,Post-Darwin Evolution Evidence,Molecular Evidence-Our increased understanding of DNA and protein structures has led to the development of more accurate phylogenetic trees.,52,1.4 Unifying Themes in Biology,Cell theory The cell theory describes the organization of living systems All living organisms are made of cells,and all living cells come from preexisting cells,Fig.1.11a,Single Celled Organisms,34,Fig.1.11b,Multi-Cellular Organisms,35,55,1.4 Unifying Themes in Biology,Molecular basis of inheritance The molecular basis of inheritance explains the continuity of life DNA encodes genes which control living organisms and are passed from one generation to the next The DNA code is similar for all organisms(The Central Dogma),Fig.1.12,37,57,Unifying Themes in Biology,Structure and Function The proper function of a molecule is dependent on its structure The structure of a molecule can often tell us about its function Four major classes of Biomolecules Nucleic Acids Amino Acids Lipids Carbohydrates,58,Unifying Themes in Biology,Evolutionary Change The diversity of life arises by evolutionary change leading to the present biodiversity we see Biology attempts to classify lifes great diversity based on these unifying themes Currently all living things are classified into 3 Domains subdivided into Kingdoms(more on taxonomy to come)This process is always changing,Fig.1.13,The Diversity of Life,Three Domains:1.Eukarya2.Archaea 3.Bacteria,40,Fig.1.13-1,Domain Eukarya is Divided into four Kingdoms:1.Plantae2.Fungi3.Animalia4.Protista,41,Fig.1.13-2,42,Fig.1.13-3,43,63,Unifying Themes in Biology,Evolutionary Conservation Evolutionary conservation explains the unity of living systems The underlying unity of biochemistry and genetics argues that all life has evolved from the same origin event Critical characteristics of early organisms are conserved and passed on to future generations,Fig.1.14,Homeodomains,45,65,Unifying Themes in Biology,Cells are information-processing systems Every cell in an organism carries the same genetic information The control of gene expression allows cells to differentiate into different cell and tissue types Cells also process information received from the environment and respond to maintain homeostasis,66,Unifying Themes in Biology,Emergent properties New properties are present at one level of organization that are not seen in the previous level The whole is greater than the sum of its parts,67,The Science of Biology,End Chapter 1,