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Thursday, August 20 • Complete the summer work display board according to the directions you picked up when you came in. Evolution, the Themes of Biology and Scientific Inquiry What are Themes? • General principles or ideas that occur over and over. • In the new AP curriculum, the themes are “the Big Ideas”. The 4 Big Ideas: E2 – I2 1. Evolution 2. Energy 3. Information 4. Interactions The Big Ideas – E2 - I2 1. Evolution – the process of evolution drives the diversity and unity of life. 2. Energy – biological systems utilize free energy and molecular building blocks to grow, to reproduce, and to maintain dynamic homeostasis. 3. Information – living systems store, retrieve, transmit and respond to information essential to life processes. 4. Interactions – biological systems interact and these systems and their interactions possess complex properties. Why Big Ideas? • We will see the Big Ideas at various times throughout the course. • The Big Ideas will be the “connectors” between the content of the course. Emergent Properties • Emergent properties result from the arrangement and interaction of parts within a system • Emergent properties characterize nonbiological entities as well – For example, a functioning bicycle emerges only when all of the necessary parts connect in the correct way Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Power and Limitations of Reductionism • Reductionism is the reduction of complex systems to simpler components that are more manageable to study – For example, the molecular structure of DNA • An understanding of biology balances reductionism with the study of emergent properties – For example, new understanding comes from studying the interactions of DNA with other molecules Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Systems Biology • A system is a combination of components that function together • Systems biology constructs models for the dynamic behavior of whole biological systems • The systems approach poses questions such as: – How does a drug for blood pressure affect other organs? – How does increasing CO2 alter the biosphere? Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Theme: Organisms interact with their environments, exchanging matter and energy • Every organism interacts with its environment, including nonliving factors and other organisms • Both organisms and their environments are affected by the interactions between them – For example, a tree takes up water and minerals from the soil and carbon dioxide from the air; the tree releases oxygen to the air and roots help form soil Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ecosystem Dynamics • 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 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-5 Sunlight Ecosystem Cycling of chemical nutrients Producers (plants and other photosynthetic organisms) Heat Chemical energy Consumers (such as animals) Heat Energy Conversion • Work requires a source of energy • Energy can be stored in different forms, for example, light, chemical, kinetic, or thermal • The energy exchange between an organism and its environment often involves energy transformations • Energy flows through an ecosystem, usually entering as light and exiting as heat Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Theme: Structure and function are correlated at all levels of biological organization • Structure and function of living organisms are closely related – For example, a leaf is thin and flat, maximizing the capture of light by chloroplasts Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Theme: Cells are an organism’s basic units of structure and function • The cell is the lowest level of organization that can perform all activities required for life • All cells: – Are enclosed by a membrane – Use DNA as their genetic information • The ability of cells to divide is the basis of all reproduction, growth, and repair of multicellular organisms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-7 25 µm • A eukaryotic cell has membrane-enclosed organelles, the largest of which is usually the nucleus • By comparison, a prokaryotic cell is simpler and usually smaller, and does not contain a nucleus or other membrane-enclosed organelles • Bacteria and Archaea are prokaryotic; plants, animals, fungi, and all other forms of life are eukaryotic Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-8 Prokaryotic cell Eukaryotic cell Membrane DNA (no nucleus) Membrane Cytoplasm Organelles Nucleus (contains DNA) 1 µm Theme: The continuity of life is based on heritable information in the form of DNA • Chromosomes contain most of a cell’s genetic material in the form of DNA (deoxyribonucleic acid) • DNA is the substance of genes • Genes are the units of inheritance that transmit information from parents to offspring Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings DNA Structure and Function • Each chromosome has one long DNA molecule with hundreds or thousands of genes • DNA is inherited by offspring from their parents • DNA controls the development and maintenance of organisms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-9 Sperm cell Nuclei containing DNA Egg cell Fertilized egg with DNA from both parents Embryo’s cells with copies of inherited DNA Offspring with traits inherited from both parents • Each DNA molecule is made up of two long chains arranged in a double helix • Each link of a chain is one of four kinds of chemical building blocks called nucleotides Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-10 Nucleus DNA Nucleotide Cell (a) DNA double helix (b) Single strand of DNA • Genes control protein production indirectly • DNA is transcribed into RNA then translated into a protein • An organism’s genome is its entire set of genetic instructions Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Systems Biology at the Levels of Cells and Molecules • The human genome and those of many other organisms have been sequenced using DNAsequencing machines • Knowledge of a cell’s genes and proteins can be integrated using a systems approach Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Friday, August 21 • What defining characteristic of life is observed when a jogging man begins to sweat and when a plant closes its stomata openings in its leaves? Why? – A. Metabolism – B. Heredity – C. Cellular makeup – D. Homeostasis Question: • How do we know what is alive and what is not? • Biology is the study of Life. • So, what are the properties of Life? • Goal – not to memorize the list of characteristics, but to be able to discuss and apply them. 1. Order • Living things are highly organized in structure and function. • Analyzing a biological structure gives us clues about what it does and how it works. • Structure and Function are related at all levels. 2. Reproduction • Organisms reproduce their own kind. 3. Nucleic Acids • Life on Earth uses the nucleic acids and codes for Heritable Information. 4. Growth & Development • Organisms increase in size and complexity. • Growth - increase in size. • Development - increase in complexity. • Life - grows by internal changes. 5. Energy Processing • Organisms take in energy and transform it to do work. • Organisms are “open” systems, they must continually take in energy. 6. Response To Environment • Organisms respond to changes or stimuli in their environment. 7. Regulation • Life processes must be controlled and adjusted. • Organisms maintain their internal environment within tolerable limits by homeostasis. • “homeo” = same • “stasis” = state Interactions- Feedback Regulation Negative Feedback- a loop where the response reduces the initial stimulus. 1.11 picture • Positive Feedback- end product speeds up its own production. • -Clotting of blood in response to injury. Chemicals are released to attract more platelets. 8. Evolutionary Adaptation • Organisms change over time because of successful adaptations to their environment. • Organisms must have successful adaptations, move, or die! Is this a “good” adaptation? 9. The Cell Is the “basic unit” of Life Levels of Biological Organization • • • • • • • • • • 1. Biosphere 2. Ecosystem 3. Communities 4. Populations 5. Organisms 6. Organs and Organ Systems 7. Tissues 8. Cells 9. Organelles 10. Molecules Levels of Biological Organization • Biosphere- all life on Earth and all places where life exists. • Ecosystem- all living and nonliving things in a particular area. • Communities • Array of organisms inhabiting a particular ecosystem. • Populations • All the individuals of a particular species • Organismsindividual living things • Organs and Organ SystemBody part that carries out specific function. • Tissues – Group of cells that work together to perform a specialized structure. • Cells- life’s fundamental unit of structure and function. Cell is about 40um, about 500 would reach across a coin. • Organellesfunctional components present in cells. • Molecules- chemical structure consisting of 2 or more atoms. Chlorophyll molecule Monday, August 24 • What is the Theory of evolution by natural selection? Who is responsible for this Theory? Basic Evolution • Nothing in Biology makes sense except in the light of Evolution. – Theodosius Dobzhansky American Biology Teacher 35:125-129, 1973. Important Notes: 1. organisms survive because of their adaptations, they do not adapt to survive. 2. individuals do not evolve, populations do. Evolution Success is by: 1. Survival - the organism has to live. 2. Reproduction – the organism has to leave progeny behind. Grouping Species: The Basic Idea • Taxonomy is the branch of biology that names and classifies species into groups of increasing breadth • Domains, followed by kingdoms, are the broadest units of classification Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-14 Species Genus Family Order Class Phylum Kingdom Domain Ursus americanus (American black bear) Ursus Ursidae Carnivora Mammalia Chordata Animalia Eukarya The Three Domains of Life • The three-domain system is currently used, and replaces the old five-kingdom system • Domain Bacteria and domain Archaea comprise the prokaryotes • Domain Eukarya includes all eukaryotic organisms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-15a (a) DOMAIN BACTERIA Fig. 1-15b (b) DOMAIN ARCHAEA • The domain Eukarya includes three multicellular kingdoms: – Plantae – Fungi – Animalia • Other eukaryotic organisms were formerly grouped into a kingdom called Protista, though these are now often grouped into many separate kingdoms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-15d Protists Fig. 1-15e Kingdom Fungi Fig. 1-15f Kingdom Plantae Fig. 1-15g Kingdom Animalia Unity in the Diversity of Life • A striking unity underlies the diversity of life; for example: – DNA is the universal genetic language common to all organisms – Unity is evident in many features of cell structure Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Charles Darwin and the Theory of Natural Selection • Fossils and other evidence document the evolution of life on Earth over billions of years Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-17 • Charles Darwin published On the Origin of Species by Means of Natural Selection in 1859 • Darwin made two main points: – Species showed evidence of “descent with modification” from common ancestors – Natural selection is the mechanism behind “descent with modification” • Darwin’s theory explained the duality of unity and diversity Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-18 Fig. 1-19 • Darwin observed that: – Individuals in a population have traits that vary – Many of these traits are heritable (passed from parents to offspring) – More offspring are produced than survive – Competition is inevitable – Species generally suit their environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Darwin inferred that: – Individuals that are best suited to their environment are more likely to survive and reproduce – Over time, more individuals in a population will have the advantageous traits • In other words, the natural environment “selects” for beneficial traits Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-20 1 Population with varied inherited traits. 2 Elimination of individuals with certain traits. 3 Reproduction of survivors. 4 Increasing frequency of traits that enhance survival and reproductive success. • Natural selection is often evident in adaptations of organisms to their way of life and environment • Bat wings are an example of adaptation Video: Soaring Hawk Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Tree of Life • “Unity in diversity” arises from “descent with modification” – For example, the forelimb of the bat, human, horse and the whale flipper all share a common skeletal architecture • Fossils provide additional evidence of anatomical unity from descent with modification Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings • Darwin proposed that natural selection could cause an ancestral species to give rise to two or more descendent species – For example, the finch species of the Galápagos Islands • Evolutionary relationships are often illustrated with tree-like diagrams that show ancestors and their descendents Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 1-22 Insect-eaters Warbler finches Gray warbler finch Certhidea fusca Bud-eater Seed-eater COMMON ANCESTOR Green warbler finch Certhidea olivacea Sharp-beaked ground finch Geospiza difficilis Vegetarian finch Platyspiza crassirostris Mangrove finch Cactospiza heliobates Insect-eaters Tree finches Woodpecker finch Cactospiza pallida Medium tree finch Camarhynchus pauper Large tree finch Camarhynchus psittacula Small tree finch Camarhynchus parvulus Cactus-flowereaters Seed-eaters Ground finches Large cactus ground finch Geospiza conirostris Cactus ground finch Geospiza scandens Small ground finch Geospiza fuliginosa Medium ground finch Geospiza fortis Large ground finch Geospiza magnirostris Video: Albatross Courtship Ritual Video: Blue-footed Boobies Courtship Ritual Video: Galápagos Islands Overview Video: Galápagos Marine Iguana Video: Galápagos Sea Lion Video: Galápagos Tortoise Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evolution in AP Biology 1. What is the adaptive value of ________? 2. Why has ______ persisted over time? 3. How does _____ increase survival or reproduction? Science is: • A process. • A way of “knowing”. • Based on observations and experiments. Observations: • Are the “keystone” to Science. • If it can’t be “observed”, it can’t be studied by the Scientific Method. • Can be made through your senses or through the use of tools. Two types of Science 1. Discovery or Descriptive Science – Naturalists, human genome – Based on observations, but may lead to experiments – Inductive Reasoning – logic flows from a set of specific observations to a general conclusion 2. Hypothesis based Science – Science by experimentation – Hypothesis testing in the form of “If…then…” – Deductive Reasoning - logic flows from general to specific Example • When I throw a ball in the air, why does it come back down? • Inductive – Whenever I have thrown a ball in the past, it always comes back down. – Specific observations to general conclusion. • Deductive – Gravity attracts two objects. – If I throw the ball into the air, then gravity should draw the ball to the earth. Scientific Method: • Outlines a series of steps for answering questions. • Note – goal is NOT to memorize these steps. • Obtains “evidence” through the use of experiments. Scientific Method Steps 1. Identify the problem. 2. What is already known? 3. Formulate a hypothesis. 4. Conduct an experiment changing one variable at a time. (Why?) 5. Collect data. Have replicates. (Why?) 6.Compare data to hypothesis. Does the data support the hypothesis? 7. Conclusions and new hypothesis Comment • Nothing is ever proven in science. – Can only be disproven • Experiments either support or fail to support a particular hypothesis. • Disproving a hypothesis is as important as supporting it. • We will learn about the 7 Science Practices in Lab. Theory (Capital T) • Broader in scope than hypothesis. • Not determined by single experiment, but have been supported by many experiments by many scientists. • Comprehensive explanation supported by abundance of evidence. • Theories allow predictions. Examples of Theories • • • • • Atomic Theory Gravitational Theory Theory of Relativity Cell Theory Theory of Evolution by Natural Selection Lower case t theories • Used in everyday language, but are NOT the same as a Theory. • Not predictive, Not testable. • Not supported by evidence • Don’t confuse Theory with theory. Chapter Summary • Big Ideas can provide a common framework for learning Biology. • What are the characteristics of Life? • How does Science work? • Evolution’s role in the study of Biology.