Chapter 1 General Biology I Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

The Science of Life Biology unifies much of natural science Life defies simple definition Living systems are the most complex chemical systems on Earth Life is constrained by the properties of chemistry and physics Science is becoming more interdisciplinary Combining multiple fields 2

The Science of Life 7 characteristics of all living organisms Cellular organization Ordered complexity Sensitivity Growth, development, and reproduction Energy utilization Homeostasis Evolutionary adaptation 3

The Science of Life Living systems show hierarchical organization Cellular level Organismal level Populational level Ecosystem level Biosphere 4

The Science of Life Living systems show hierarchical organization Cellular level Atoms, molecules, organelles, cells Cell is the basic unit of life Organismal level Tissues, organs, organ systems Populational level Population, community Ecosystem level Biosphere All the livable space on the planet 99% of it is in the ocean!!! 5

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Populational Level 8 POPULATIONAL LEVEL Population Species Community Ecosystem Biosphere PM: alphas correct as set with photo source if not set w/art? Pl. confirm thru-out (population): © George Ostertag/agefotostock; (species): © PhotoDisc/Volume 44 RF; (community): © Ryan McGinnis/Alamy; (ecosystem): © Robert and Jean Pollock; (biosphere): NASA 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

The Science of Life As you move up the hierarchy, novel properties emerge Result from interaction of components Cannot be deduced by looking at parts themselves “Life” is an emergent property Populational correct as set? 9

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 Classification of all life on Earth Human genome sequencing 10

The Nature of Science Science uses both deductive and inductive reasoning Deductive reasoning uses general principles to make specific predictions If all mammals have hair and you find an animal that doesn’t, you might say that the animal you are looking at is not a mammal Used to test the validity of general ideas in all branches of knowledge Inductive reasoning uses specific observations to develop general conclusions If poodles have hair and terriers have hair, then you might generalize that all dogs have hair 11

The Nature of Science Scientists use a systematic approach to gain understanding of the natural world = Scientific Method Observation Hypothesis formation Prediction Experimentation Conclusion 12

The Nature of Science A hypothesis is a possible explanation for an observation Not just an “educated guess” A hypothesis Must be tested to determine its validity Is often tested in many different ways Allows for predictions to be made Iterative Hypotheses can be changed and refined with new data 14

The Nature of Science 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 15

The Nature of Science Predictions Hypotheses should make predictions Predictions provide a way to test the validity of hypotheses Hypothesis must be rejected if the experiment produces results inconsistent with the predictions The more experimentally supported predictions a hypothesis makes, the more valid the hypothesis 16

The Nature of Science Philosophical approaches to science Reductionism To break a complex process down to its simpler parts For example Cellular metabolism is very complex, reductionism is looking at one pathway and the function of that enzyme However, that enzyme may work differently when not isolated from other enzymes and molecules within the cell Systems biology Focus on emergent properties that can’t be understood by looking at simpler parts 18

The Nature of Science Models in science Way to organize thought Parts provided by reductionist approach Model shows how they fit together Suggest experiments to test the model 19

The Nature of Science 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 When you say “theory” in science, it is as close to fact that you will get to with the information and technology we have available to us at the time Compare to general meaning of theory Different in everyday language, implies a lack of knowledge or a guess 20

Darwin and Evolution Example of how a scientist develops a hypothesis and a theory gains acceptance Charles Darwin served as naturalist on mapping expedition around coastal South America 30 years of observation and study before publishing On the Origin of Species by Means of Natural Selection 21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Voyage of the HMS Beagle Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. British Isles Western Isles EUROPE ASIA NORTH AMERICA NORTH PACIFIC OCEAN NORTH ATLANTIC OCEAN NORTH PACIFIC OCEAN Canary Islands Cape Verde Islands Philippine Islands Galápagos Islands AFRICA INDIAN OCEAN Keeling Islands Equator SOUTH AMERICA Ascension Madagascar Bahia Marquesas St. Helena Friendly Islands Mauritius Bourbon Island Valparaiso Rio de Janeiro AUSTRALIA Society Islands Sydney Montevideo Cape of Good Hope Buenos Aires King George’s Sound Port Desire Hobart New Zealand Straits of Magellan Falkland Islands SOUTH ATLANTIC OCEAN Cape Horn Tierra del Fuego 22

Darwin and Evolution Darwin was not the first to propose evolution Living things have changed over time Darwin’s contribution was a mechanism for evolution He proposed Natural selection 23

Darwin and Evolution On the Beagle, Darwin saw that characteristics of similar species varied from place to place Galápagos Finches 14 related species differ only slightly “Descent with modification” or evolution Woodpecker Finch (Cactospiza pallida) Large Ground Finch (Geospiza magnirostris) Cactus Finch (Geospiza scandens) 24 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Darwin and Evolution Darwin studied Thomas Malthus’s An Essay on the Principle of Population Populations of plants and animals increase geometrically (multiplicative, example x3) Humans can only increase their food supply arithmetically (additive, example +2) Populations of species remain constant because death limits population numbers There are individuals that possess physical, behavioral or other attributes that give them an advantage 25

Darwin and Evolution Darwin saw that: Every organism has the potential to produce more offspring But, only a limited number survive and reproduce themselves Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. geometric progression arithmetic progression 54 Human Growth is Geometric Human food production is Arithmetic 18 6 8 2 6 4 26

Darwin and Evolution Darwin made an important association: Individuals with attributes that give them an advantage in their environment are more likely to survive and reproduce Pass these characteristics on to their offspring The population will gradually change over time Darwin called this selection

Darwin and Evolution Evidence supporting Darwin’s theory has only grown Fossil record Earth’s age Mechanism for heredity Comparative anatomy Molecular Evidence 28

Darwin and Evolution Fossil record Earth’s age Transitional forms have been found at predicted positions in time Earth’s age Earth is very old – 4.5 billion years old 29

Darwin and Evolution Mechanism for heredity Mendel’s laws of inheritance were unknown to Darwin At time of Darwin there was no concept of “genes” or how heredity worked Darwin could not completely explain how evolution worked Now have detailed understanding of heredity 30

Darwin and Evolution Comparative anatomy Vertebrate forelimbs all share the same basic array of bones Homologous – same evolutionary origin but now differ in structure and function Analogous – structures of different origin used for the same purpose (butterfly and bird wings) 31

Unifying Themes in Biology Cell theory All organisms composed of cells Cells are life’s basic units All cells come from preexisting cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. 60 µm 34 b. 500 µm a: © Dennis Kunkel/Phototake; b: © Karl E. Deckart/Phototake

Unifying Themes in Biology Molecular basis of inheritance Deoxyribonucleic acid (DNA) Sequence of 4 nucleotides encode all of a cell’s information – A, T, C, G Gene – discrete unit of information Genome – entire set of DNA instructions Continuity of life depends on faithful copying of DNA into daughter cells 35

Unifying Themes in Biology Structure and function Study structure to learn function Know a function – look for that structure in other organisms Example Receptor on human cell for insulin known Find similar molecule in a worm Might conclude this molecule functions the same in the worm 36

Unifying Themes in Biology Diversity of life arises by evolution Underlying unity of biochemistry and genetics argues for life from the same origin event Diversity due to evolutionary change over time 3 domains Bacteria – single-celled prokaryote, bacteria Archaea – single-celled prokaryote, includes extremophile bacteria Eukarya – single-celled or multicellular eukaryote; includes protists, fungi, plants, and animals. 37

38 Plantae Fungi Eukarya Animalia Protista Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Plantae Fungi Eukarya Animalia Protista (plantae middle): © David M. Dennis/Animals Animals; (plantae right): © Corbis/Volume 46 RF; (fungi left): © Royalty Free/Corbis; (fungi middle): © Mediscan/Corbis; (fungi right): © PhotoDisc BS/Volume 15 RF; (animalia left): © Royalty-Free/Corbis; (animalia middle): © Tom Brakefield/Corbis; (animalia right): © PhotoDisc/Volume 44 RF; (protista left): © Corbis/Volume 64 RF; (protista middle): © Tom Adams/Visuals Unlimited; (protista right): © Douglas P. Wilson/Frank Lane Picture Agency/Corbis 38

Unifying Themes in Biology Evolutionary conservation All organisms today descended from a simple creature 3.5 BYA Some characteristics preserved Our DNA encodes everything For example, you need certain enzymes for cellular respiration, those are encoded in your DNA; those same enzymes are used by other organisms for the same process Conservation reflects that they have a fundamental role 39

Unifying Themes in Biology Cells are information-processing systems Information in DNA used to direct synthesis of cellular components Control of gene expression leads to different cells/ tissue types Cells process environmental information Glucose levels, presence of hormones Cells in multicellular organisms must coordinate with each other 40

Unifying Themes in Biology Nonequilibrium state Living systems are open systems Constant supply of energy needed Self-organizing properties at different levels Emergent properties from collections of molecules, cells, and individuals 41